BASIC WELDING FILLER METAL...

BASICWELDING FILLER METAL

TECHNOLOGY

A Correspondence Course

LESSON ITHE BASICS OF ARC WELDING

©COPYRIGHT 2000 THE ESAB GROUP, INC.

ESAB ESAB Welding &Cutting Products

An Introduction to MetalsElectricity for Welding

Lesson 1 The Basics of Arc

Welding

Lesson 2 Common Electric

Arc Welding Processes

Lesson 3 Covered Electrodes

for Welding Mild Steels


for Welding Low Alloy Steels

Lesson 5 Welding Filler Metals for Stainless Steels

Lesson 6 Carbon & Low Alloy Steel Filler Metals - GMAW,GTAW,SAW

Lesson 7 Flux Cored Arc

Electrodes Carbon Low Alloy Steels

Lesson 8 Hardsurfacing

Electrodes

Lesson 9 Estimating &

Comparing Weld Metal Costs

Lesson 10 Reliability of Welding

Filler Metals

© COPYRIGHT 1998 THE ESAB GROUP, INC

TABLE OF CONTENTSLESSON I

THE BASICS OF ARC WELDING

PART A. AN INTRODUCTION TO METALS

Section Nr. Section Title Page

1.1 Source and Manufacturing............................................................. 1

1.1.1 Rimmed Steel ................................................................................... 2

1.1.2 Capped Steel .................................................................................... 2

1.1.3 Killed Steel ........................................................................................ 3

1.1.4 Semi-Killed Steel............................................................................... 3

1.1.5 Vacuum Deoxidized Steel ................................................................. 31.2 Classification of Steels................................................................... 3

1.2.1 Carbon Steel ..................................................................................... 3

1.2.2 Low Alloy Steel.................................................................................. 3

1.2.3 High Alloy Steel ................................................................................. 41.3 Specifications ................................................................................. 51.4 Crystalline Structure of Metals ...................................................... 6

1.4.1 Grains and Grain Boundaries ........................................................... 7

1.5 Heat Treatment ................................................................................ 8

1.5.1 Preheat ............................................................................................. 8

1.5.2 Stress Relieving ................................................................................ 9

1.5.3 Hardening ......................................................................................... 9

1.5.4 Tempering ......................................................................................... 9

1.5.5 Annealing .......................................................................................... 9

1.5.6 Normalizing ....................................................................................... 10

1.5.7 Heat Treatment Trade-Off ................................................................. 101.6 Properties of Metals........................................................................ 10

1.6.1 Tensile Strength ................................................................................ 10

1.6.2 Yield Strength.................................................................................... 11

1.6.3 Ultimate Tensile Strength .................................................................. 11

1.6.4 Percentage of Elongation ................................................................. 11


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TABLE OF CONTENTSLESSON I - Con't.

1.6.5 Reduction of Area ............................................................................. 11

1.6.6 Charpy Impacts ................................................................................. 11

1.6.7 Fatigue Strength ............................................................................... 12

1.6.8 Creep Strength.................................................................................. 13

1.6.9 Oxidation Resistance ........................................................................ 13

1.6.10 Hardness Test ................................................................................... 13

1.6.11 Coefficient of Expansion ................................................................... 14

1.6.12 Thermal Conductivity ........................................................................ 141.7 Effects of Alloying Elements .......................................................... 14

1.7.1 Carbon .............................................................................................. 14

1.7.2 Sulphur ............................................................................................. 14

1.7.3 Manganese ....................................................................................... 15

1.7.4 Chromium ......................................................................................... 15

1.7.5 Nickel ................................................................................................ 15

1.7.6 Molybdenum ..................................................................................... 15

1.7.7 Silicon ............................................................................................... 15

1.7.8 Phosphorus....................................................................................... 15

1.7.9 Aluminum .......................................................................................... 15

1.7.10 Copper .............................................................................................. 15

1.7.11 Columbium........................................................................................ 16

1.7.12 Tungsten ........................................................................................... 16

1.7.13 Vanadium .......................................................................................... 16

1.7.14 Nitrogen ............................................................................................ 16

1.7.15 Alloying Elements summary ............................................................. 16

PART B. ELECTRICITY FOR WELDING


1.8 Electricity for Welding ....................................................................... 17

1.8.1 Principles of Electricity ...................................................................... 17

1.8.2 Ohm’s Law ........................................................................................ 18

1.8.3 Electrical Power ................................................................................ 19

1.8.4 Power Generation ............................................................................. 20


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TABLE OF CONTENTSLESSON I - Con't.

1.8.5 Transformers .................................................................................... 22

1.8.6 Power Requirements ........................................................................ 24

1.8.7 Rectifying AC to DC .......................................................................... 25

1.9 Constant Current or Constant Voltage .............................................. 26

1.9.1 Constant Current Characteristics ...................................................... 26

1.9.2 Constant Voltage Characteristics ...................................................... 26

1.9.3 Types of Welding Power Sources ..................................................... 27

1.9.4 Power Source Controls ..................................................................... 28

Appendix A Glossary of Terms ............................................................................. 29


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LESSON I, PART A

AN INTRODUCTION TO METALS

1.1 SOURCE AND MANUFACTURING

Metals come from natural deposits of ore in the earth’s crust. Most ores are contaminated

with impurities that must be removed by mechanical and chemical means. Metal extracted

from the purified ore is known as primary or virgin metal, and metal that comes from scrap

is called secondary metal. Most mining of metal bearing ores is done by either open pit or

underground methods. The two methods of mining employed are known as “selective” in

which small veins or beds of high grade ore are worked, and “bulk” in which large quantities

of low grade ore are mined to extract a high grade portion.

1.1.0.1 There are two types of ores, ferrous and nonferrous. The term ferrous comes

from the Latin word “ferrum” meaning iron, and a ferrous metal is one that has a high iron

content. Nonferrous metals, such as copper and aluminum, are those that contain little or

no iron. There is approximately 20 times the tonnage of iron in the earth’s crust compared

to all other nonferrous products combined; therefore, it is the most important and widely

used metal.

1.1.0.2 Aluminum, because of its attractive appearance, light weight and strength, is the

next most widely used metal. Commercial aluminum ore, known as bauxite, is a residual

deposit formed at or near the earth’s surface.

1.1.0.3 Some of the chemical processes that occur during steel making are repeated

during the welding operation and an understanding of welding metallurgy can be gained by

imagining the welding arc as a miniature steel mill.

1.1.0.4 The largest percentage of commercially produced iron comes from the blast

furnace process. A typical blast furnace is a circular shaft approximately 90 to 100 feet in

height with an internal diameter of approximately 28 feet. The steel shell of the furnace is

lined with a refractory material, usually a hard, dense clay firebrick.

1.1.0.5 The iron blast furnace utilizes the chemical reaction between a solid fuel charge

and the resulting rising column of gas in the furnace. The three different materials used for

the charge are ore, flux and coke. The ore consists of iron oxide about four inches in

diameter. The flux is limestone that decomposes into calcium oxide and carbon dioxide.

The lime reacts with impurities in the ore and floats them to the surface in the form of a

slag. Coke, which is primarily carbon, is the ideal fuel for blast furnaces because it

produces carbon monoxide gas, the main agent for reducing iron ore into iron metal.


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LESSON I, PART A

1.1.0.6 The basic operation of the blast furnace is to reduce iron oxide to iron metal and

to remove impurities from the metal. Reduced elements pass into the iron and oxidized

elements dissolve into the slag. The metal that comes from the blast furnace is called pig

iron and is used as a starting material for further purification processes.

1.1.0.7 Pig iron contains excessive amounts of elements that must be reduced before

steel can be produced. Different types of furnaces, most notably the open hearth, electric

and basic oxygen, are used to continue this refining process. Each furnace performs the

task of removing or reducing elements such as carbon, silicon, phosphorus, sulfur and

nitrogen by saturating the molten metal with oxygen and slag forming ingredients. The

oxygen reduces elements by forming gases that are blown away and the slag attracts

impurities as it separates from the molten metal.

1.1.0.8 Depending upon the type of slag that is used, refining furnaces are classed as

either acid or basic. Large amounts of lime are contained in basic slags and high quantities

of silica are present in acid slags. This differential between acid and basic slags is also

present in welding electrodes for much of the same refining process occurs in the welding

operation.

1.1.0.9 After passing through the refining furnace, the metal is poured into cast iron ingot

molds. The ingot produced is a rather large square column of steel. At this point, the metal

is saturated with oxygen. To avoid the formation of large gas pockets in the cast metal, a

substantial portion of the oxygen must be removed. This process is known as deoxidation,

and it is accomplished through additives that tie up the oxygen either through gases or in

slag. There are various degrees of oxidation, and the common ingots resulting from each

are as follows:

1.1.1 Rimmed Steel - The making of rimmed steels involves the least deoxidation. As

the ingots solidify, a layer of nearly pure iron is formed on the walls and bottom of the mold,

and practically all the carbon, phosphorus, and sulfur segregate to the central core. The

oxygen forms carbon monoxide gas and it is trapped in the solidifying metal as blow holes

that disappear in the hot rolling process. The chief advantage of rimmed steel is the excel-

lent defect-free surface that can be produced with the aide of the pure iron skin. Most

rimmed steels are low carbon steels containing less than .1% carbon.

1.1.2 Capped Steel - Capped steel regulates the amount of oxygen in the molten

metal through the use of a heavy cap that is locked on top of the mold after the metal is

allowed to reach a slight level of rimming. Capped steels contain a more uniform core

composition than the rimmed steels. Capped steels are, therefore, used in applications


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LESSON I, PART A

that require excellent surfaces, a more homogenous composition, and better mechanical

properties than rimmed steel.

1.1.3 Killed Steel - Unlike rimmed or capped steel, killed steel is made by completely

removing or tying up the oxygen before the ingot solidifies to prevent the rimming action.

This removal is accomplished by adding a ferro-silicon alloy that combines with oxygen to

form a slag, leaving a dense and homogenous metal.

1.1.4 Semi-killed Steel - Semi-killed steel is a compromise between rimmed and killed

steel. A small amount of deoxidizing agent, generally ferro-silicon or aluminum, is added.

The amount is just sufficient to kill any rimming action, leaving some dissolved oxygen.

1.1.5 Vacuum Deoxidized Steel - The object of vacuum deoxidation is to remove

oxygen from the molten steel without adding an element that forms nonmetallic inclusions.

This is done by increasing the carbon content of the steel and then subjecting the molten

metal to vacuum pouring or steam degassing. The carbon reacts with the oxygen to form

carbon monoxide, and as a result, the carbon and oxygen levels fall within specified limits.

Because no deoxidizing elements that form solid oxides are used, the steel produced by

this process is quite clean.

1.2 CLASSIFICATIONS OF STEEL

The three commonly used classifications for steel are: carbon, low alloy, and high alloy.

These are referred to as the “type” of steel.

1.2.1 Carbon Steel - Steel is basically an alloy of iron and carbon, and it attains its

strength and hardness levels primarily through the addition of carbon. Carbon steels are

classed into four groups, depending on their carbon levels.

Low Carbon Up to 0.15% carbon

Mild Carbon Steels .15% to 0.29% carbon

Medium Carbon Steels .30% to 0.59% carbon

High Carbon Steels .60% to 1.70% carbon

1.2.1.1 The largest tonnage of steel produced falls into the low and mild carbon steel

groups. They are popular because of their relative strength and ease with which they can

be welded.

1.2.2 Low Alloy Steel - Low alloy steel, as the name implies, contains small amounts

of alloying elements that produce remarkable improvements in their properties. Alloying


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LESSON I, PART A

elements are added to improve strength and toughness, to decrease or increase the

response to heat treatment, and to retard rusting and corrosion. Low alloy steel is gener-

ally defined as having a 1.5% to 5% total alloy content. Common alloying elements are

manganese, silicon, chromium, nickel, molybdenum, and vanadium. Low alloy steels may

contain as many as four or five of these alloys in varying amounts.

1.2.2.1 Low alloy steels have higher tensile and yield strengths than mild steel or carbon

structural steel. Since they have high strength-to-weight ratios, they reduce dead weight in

railroad cars, truck frames, heavy equipment, etc.

1.2.2.2 Ordinary carbon steels, that exhibit brittleness at low temperatures, are unreliable

in critical applications. Therefore, low alloy steels with nickel additions are often used for

low temperature situations.

1.2.2.3 Steels lose much of their strength at high temperatures. To provide for this loss

of strength at elevated temperatures, small amounts of chromium or molybdenum are

added.

1.2.3 High Alloy Steel - This group of expensive and specialized steels contain alloy

levels in excess of 10%, giving them outstanding properties.

1.2.3.1 Austenitic manganese steel contains high carbon and manganese levels, that

give it two exceptional qualities, the ability to harden while undergoing cold work and great

toughness. The term austenitic refers to the crystalline structure of these steels.

1.2.3.2 Stainless steels are high alloy steels that have the ability to resist corrosion. This

characteristic is mainly due to the high chromium content, i.e., 10% or greater. Nickel is

also used in substantial quantities in some stainless steels.

1.2.3.3 Tool steels are used for cutting and forming operations. They are high quality

steels used in making tools, punches, forming dies, extruding dies, forgings and so forth.

Depending upon their properties and usage, they are sometimes referred to as water

hardening, shock resisting, oil hardening, air hardening, and hot work tool steel.

1.2.3.4 Because of the high levels of alloying elements, special care and practices are

required when welding high alloy steels.


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LESSON I, PART A

1.3 SPECIFICATIONS

Many steel producers have developed steels that they market under a trade name such as

Cor-Ten, HY-80, T-1, NA-XTRA, or SS-100, but usually a type of steel is referred to by its

specification. A variety of technical, governmental and industrial associations issue

specifications for the purpose of classifying materials by their chemical composition,

properties or usage. The specification agencies most closely related to the steel industry

are the American Iron and Steel Institute (AISI), Society of Automotive Engineers (SAE),

American Society for Testing and Materials (ASTM), and the American Society of

Mechanical Engineers (ASME).

1.3.0.1 The American Iron and Steel Institute (AISI) and the Society of Automobile

Engineers (SAE) have collaborated in providing identical numerical designations for their

specifications. The first two digits of a four digit index number refer to a series of steels

classified by their composition or alloy combination. While the last two digits, which can

change within the same series, give an approximate average of the carbon range. For

example, the first two digits of a type 1010 or 1020 steel indicate a “10” series that has

carbon as its main alloy. The last two digits indicate an approximate average content of

.10% or .20% carbon, respectively. Likewise, the “41” of a 4130 type steel refers to a group

that has chromium and molybdenum as their main alloy combination with approximately

.30% carbon content.

1.3.0.2 The AISI classifications for certain alloys, such as stainless steel, are somewhat

different. They follow a three digit classification with the first digit designating the main

alloy composition or series. The last two digits will change within a series, but are of an

arbitrary nature being agreed upon by industry as a designation for certain compositions

within the series. For example, the “3” in a 300 series of stainless steel indicates chromium

and nickel as the main alloys, but a 308 stainless has a different overall composition than a

347 type. The “4” of a 400 series indicates the main alloy as chromium, but there are

different types such as 410, 420, 430, and so forth within the series.

1.3.0.3 The American Society for Testing and Materials (ASTM) is the largest

organization of its kind in the world. It has compiled some 48 volumes of standards for

materials, specifications, testing methods and recommended practices for a variety of

materials ranging from textiles and plastics to concrete and metals.

1.3.0.4 Two ASTM designated steels commonly specified for construction are A36-77

and A242-79. The prefix letter indicates the class of a material. In this case, the letter “A”indicates a ferrous metal, the class of widest interest in welding. The numbers 36 and 242


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© COPYRIGHT 1999 THE ESAB GROUP

LESSON I, PART A

are index numbers. The 77 and 79 refer to the year that the standards for these steels

were originally adopted or the date of their latest revision.

1.3.0.5 The ASTM designation may be further subdivided into Grades or Classes. Since

many standards for ferrous metals are written to cover forms of steel (i.e., sheet, bar, plate,

etc.) or particular products fabricated from steel (i.e., steel rail, pipe, chain, etc.), the user

may select from a number of different types of steel under the same classification. The

different types are than placed under grades or classes as a way of indicating the

differences in such things as chemistries, properties, heat treatment, etc. An example of a

full designation is A285-78 Grade A or A485-79 Class 70.

1.3.0.6 The American Society of Mechanical Engineers (ASME) maintains a widely used

ASME Boiler and Pressure Vessel Code. The material specification as adopted by the

ASME is identified with a prefix letter “S”, while the remainder is identical with ASTM with

the exception that the date of adoption or revision by ASTM is not shown. Therefore, a

common example of an ASME classification is SA 387 Grade 11, Class 1.

1.4 CRYSTALLINE STRUCTURE OF METALS

When a liquid metal is cooled, its atoms will assemble into a regular crystal pattern and we

say the liquid has solidified or crystallized. All metals solidify as a crystalline material. In a

crystal the atoms or molecules are held in a fixed position and are not free to move about

as are the molecules of a liquid or gas. This fixed position is called a crystal lattice. As the

temperature of a crystal is raised, more thermal energy is absorbed by the atoms or

molecules and their movement increases. As the distance

between the atoms increases, the lattice breaks down and

the crystal melts. If a lattice contains only one type of atom,

as in pure iron, the conditions are the same at all points

throughout the lattice, and the crystal melts at a single

temperature (see Figure 1).

FIGURE 1

4000

3000

2000

1000

TIMESOLID-LIQUID TRANSFORMATION, PURE IRON

LIQUID

2795°F

SOLID


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LESSON I, PART A

1.4.0.1 However, if the lattice contains two

or more types of atoms, as in any alloy-steel,

it may start to melt at one temperature but not

be completely molten until it has been heated

to a higher temperature (See Figure 2). This

creates a situation where there is a

combination of liquids and solids within a

range of temperatures.

1.4.0.2 Each metal has a characteristic

crystal structure that forms during

solidification and often remains the permanent

form of the material as long as it remains at

room temperature. However, some metals

may undergo an alteration in the crystalline

form as the temperature is changed. This is known as phase transformation. For example,

pure iron solidifies at 2795°F, the delta structure transforms into a structure referred to as

gamma iron. Gamma iron is commonly known as austenite and is a nonmagnetic

structure. At a temperature of 1670°F., the pure iron structure transforms back to the delta

iron form, but at this temperature, the metal is known as alpha iron. These two phases are

given different names to differentiate between the high temperature phase (delta) and the

low temperature phase (alpha). The capability of the atoms of a material to transform into

two or more crystalline structures at different temperatures is defined as allotropic. Steels

and iron are allotropic metals.

1.4.1 Grains and Grain Boundaries - As the metal is cooled to its freezing point, a

small group of atoms begin to assemble into crystalline form (refer to Figure 3). These

small crystals scattered throughout the body of the liquid are oriented in all directions and

as solidification continues, more crystals are formed from the surrounding liquid. Often,

they take the form of dendrites, or a treelike structure. As crystallization continues, the

crystals begin to touch one another, their free growth hampered, and the remaining liquid

freezes to the adjacent crystals until solidification is complete. The solid is now composed

of individual crystals that usually meet at different orientations. Where these crystals meet

is called a grain boundary.

1.4.1.2 A number of conditions influence the initial grain size. It is important to know that

cooling rate and temperature has an important influence on the newly solidified grain

structure and grain size. To illustrate differences in grain formation, let's look at the cooling

phases in a weld.

FIGURE 2

TIME


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Liquid



Liquid and Solid



Solid



Solid-Liquid Transformation, Alloy Metal






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LESSON I, PART A

1.4.1.3 Initial crystal formation begins at the coolest spot in the weld. That spot is at the

point where the molten metal and the unmelted base metal meet. As the metal continues

to solidify, you will note that the grains in the center are smaller and finer in texture than the

grains at the outer boundaries of the weld deposit. This is explained by the fact that as the

weld metal cools, the heat from the center of the weld deposit will dissipate into the base

metal through the outer grains that solidified first. Consequently, the grains that solidified

first were at high temperatures for a longer time while in the solid state and this is a

situation that encourages grain growth. Grain size can have an effect on the soundness of

the weld. The smaller grains are stronger and more ductile than the larger grains. If a

crack occurs, the tendency is for it to start in the area where the grains are largest.

1.4.1.4 To summarize this section, it should be understood that all metals are composed

of crystals of grains. The shape and characteristics of crystals are determined by the

arrangement of their atoms. The atomic pattern of a single element can change its

arrangement at different temperatures, and that this atomic pattern or microstructure

determines the properties of the metals.

1.5 HEAT TREATMENT

The temperature that metal is heated, the length of time it is held at that temperature, and

the rate that it is cooled, all have an effect on a metal's crystalline structure. This crystalline

structure, commonly referred to as "microstructure," determines the specific properties of

metals. There are various ways of manipulating the microstructure, either at the steel mill

or in the welding procedure. Some of the more common ways are as follows:

1.5.1 Preheat - Most metals are rather good conductors of heat. As a result, the heat

in the weld area is rapidly dispersed through the whole weldment to all surfaces where it is

radiated to the atmosphere causing comparatively rapid cooling. In some metals, this rapid

cooling may contribute to the formation of microstructures in the weld zone that are detri-

mental. Preheating the weldment before it is welded is a method of slowing the cooling

FIGURE 3

GRAINBOUNDARIES

DENDRITE INITIAL COMPLETEFORMATION CRYSTAL FORMATION SOLIDIFICATION

BASEMETAL


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LESSON I, PART A

rate of the metal. The preheat temperature may vary from 150°F to 1000°F, but more

commonly it is held in the 300°F to 400°F range. The thicker the weld metal, the more

likely will it be necessary to preheat, because the heat will be conducted away from the

weld zone more rapidly as the mass increases.

1.5.2 Stress Relieving - Metals expand when heated and contract when cooled. The

amount of expansion is directly proportional to the amount of heat applied. In a weldment,

the metal closest to the weld is subjected to the highest temperature, and as the distance

from the weld zone increases, the maximum temperature reached decreases. This nonuni-

form heating causes nonuniform expansion and contraction and can cause distortion and

internal stresses within the weldment. Depending on its composition and usage, the metal

may not be able to resist these stresses and cracking or early failure of the part may occur.

One way to minimize these stresses or to relieve them is by uniformly heating the structure

after it has been welded. The metal is heated to temperatures just below the point where a

microstructure change would occur and then it is cooled at a slow rate.

1.5.3 Hardening - The hardness of steel may be increased by heating it to 50°F to

100°F above the temperature that a microstructure change occurs, and then placing the

metal in a liquid solution that rapidly cools it. This rapid cooling, known as "quenching,"locks in place microstructures known as "martensite" that contribute to a metal's hardness

characteristic. The quenching solutions used in this process are rated according to the

speed that they cool the metal, i.e., Oil (fast), Water (faster), Salt Brine (fastest).

1.5.4 Tempering - After a metal is quenches, it is then usually tempered. Tempering is

a process where the metal is reheated to somewhere below 1335°F, held at that tempera-

ture for a length of time, and then cooled to room temperature. Tempering reduces the

brittleness that is characteristic in hardened steels, thereby producing a good balance

between high strength and toughness. The term toughness, as it applies to metals, usually

refers to resistance to brittle fracture or notch toughness under certain environmental

conditions. More information on these properties will be covered later in this lesson and in

subsequent lessons. Steels that respond to this type of treatment are known as "quenchedand tempered steels."

1.5.5 Annealing - A metal that is annealed is heated to a temperature 50° to 100°

above where a microstructure change occurs, held at that temperature for a sufficient time

for a uniform change to take place, and then cooled at a very slow rate, usually in a fur-

nace. The principal reason for annealing is to soften steel and create a uniform fine grain

structure. Welded parts are seldom annealed for the high temperatures would cause

distortion.


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LESSON I, PART A

1.5.6 Normalizing - The main difference between normalizing and annealing is the

method of cooling. Normalized steel is heated to a temperature approximately 100° above

where the microstructure transforms and then cooled in still air rather than in a furnace.

1.5.7 Heat Treatment Trade-Off - It must be noted that these various ways of control-

ling the heating and cooling of metals can produce a desired property, but sometimes at the

expense of another desirable property. An example of this trade-off is evident in the fact

that certain heat treatments can increase the strength or hardness of metal, but the same

treatments will also make the metal less ductile or more brittle, and therefore, susceptible

to welding problems.

1.6 PROPERTIES OF METALS

The usefulness of a particular metal is determined by the climate and conditions in which it

will be used. A metal that is stamped into an automobile fender must be softer and more

pliable than armor plate that must withstand an explosive force, or the material used for an

oil rig on the Alaska North Slope must perform in a quite different climate than a steam

boiler. It becomes obvious that before a material is recommended for a specific use, the

physical and mechanical properties of that metal and the weld metal designed to join it

must be evaluated. Some of the more important properties of metals and the means of

evaluation are as follows:

1.6.1 Tensile Strength - Tensile strength is one of the most important determining

factors in selecting a metal, especially if it is to be a structural member, part of a machine,

or part of a pressure vessel.

1.6.1.1 The tensile test is performed as shown in Figure 4. The test specimen is

machined to exact standard dimensions and clamped into the testing apparatus at both

ends. The specimen is then

pulled to the point of fracture

and the data recorded.

1.6.1.2 The tensile strength

test gives us 4 primary pieces

of information: (1) Yield

Strength, (2) Ultimate Tensile

Strength, (3) Elongation, and (4)

Reduction in Area.

FIGURE 4

RECORDINGDIAL

TESTSPECIMEN

FORCE

TENSILE TESTING APPARATUS


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LESSON I, PART A

1.6.2 Yield Strength - When a metal is placed in tension, it acts somewhat like a

rubberband. When a load of limited magnitude is applied, the metal stretches, and when

the load is released, the metal returns to its original shape. This is the elastic characteristic

of metal and is represented by letter A in Figure 5. As a greater load is applied, the metal

will reach a point where it will no longer return to its original shape but will continue to

stretch. Yield strength is the point where the metal reaches the limit of its elastic character-

istic and will no longer return to its original shape.

1.6.3 Ultimate Tensile Strength - Once a metal has exceeded its yield point, it will

continue to stretch or deform, and if the load is suddenly released, the metal will not return

to its original shape, but will remain in its elongated form. This is called the plastic region of

the metal and is represented by the letter B in Figure 5. As this plastic deformation in-

creases, the metal strains

against further elongation, and

an increased load must be

applied to stretch the metal. As

the load is increased, the metal

will finally reach a point where it

no longer resists and any fur-

ther load applied will rapidly

cause the metal to break. That

point at which the metal has

withstood or resisted the maximum applied load is its ultimate tensile strength. This infor-

mation is usually recorded in pounds per square inch (psi).

1.6.4 Percentage of Elongation - Before a tensile specimen is placed in the tensile

tester, two marks at a measured distance are placed on the opposing ends of the circular

shaft. After the specimen is fractured, the distance between the marks is measured and

recorded as a percentage of the original distance. See Figure 5. This is the percentage of

elongation and it gives an indication of the ductility of the metal at room temperature.

1.6.5 Reduction of Area - A tensile specimen is machined to exact dimensions. The

area of its midpoint cross-section is a known figure. As the specimen is loaded to the point

of fracture, the area where it breaks is reduced in size. See Figure 5. This reduced area is

calculated and recorded as a percentage of the original cross-sectional area. This informa-

tion reflects the relative ductility or brittleness of the metal.

1.6.6 Charpy Impacts - Metal that is normally strong and ductile at room temperature

may become very brittle at much lower temperatures, and thus, is susceptible to fracture if

FIGURE 5

STRAIN - INCHESA B C

NOMINAL STRESS - STRAIN CURVE


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Reductionof Area



Fracture



Yield Strength Lesson 5 Welding Filler Metals for Stainless Steels

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LESSON I, PART A

a sharp abrupt load is applied to it. An impact tester measures the degree of susceptibility

to what is called brittle fracture.

1.6.6.1 The impact specimen is machined to exact dimensions (Figure 6) and then

notched on one side. Quite often, the notch is in the form of a "V" and the test in this case

is referred to as a Charpy V-Notch Impact Test. The specimen is cooled to a

predetermined temperature and then placed in a stationary clamp at the base of the testing

machine. The specimen is in the direct path of a weighted hammer attached to a

pendulum (Figure 6).

1.6.6.2 The hammer is released from a fixed height and the energy required to fracture

the specimen is recorded in ft-lbs. A specimen that is cooled to -60°F and absorbs 40 ft-lbs

of energy is more ductile, and therefore, more suitable for low temperature service than a

specimen that withstands only 10 ft-lbs at the same temperature. The specimen that

withstood 40 ft-lbs energy is said to have better toughness or notch toughness.

1.6.7 Fatigue Strength - A metal will withstand a load less than its ultimate tensile

strength but may break if that load is removed and then reapplied several times. For ex-

ample, if a thin wire is bent once, but if it is bent back and forth repeatedly, it will eventually

fracture and it is said to have exceeded its fatigue strength. A common test for this

strength is to place a specimen in a machine that repeatedly applies the same load first in

tension and then in compression. The fatigue strength is calculated from the number of

cycles the metal withstands before the point of failure is reached.

FIGURE 6

FRACTURES CRACKS DEFORMS

CHARPY V-NOTCHSPECIMEN

ENERGYIN FT/LBS

CHARPY IMPACT TEST MACHINE

CHARPY V-NOTCH IMPACT TEST


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1.6.8 Creep Strength - If a load below a metal's tensile strength is applied at room

temperature (72°F), it will cause some initial elongation, but there will be no further measur-

able elongation if the load is kept at a constant level. If that same load were applied to a

metal heated to a high temperature, the situation would change. Although the load is held

at a constant level, the metal will gradually continue to elongate. This characteristic is

called creep. Eventually, the material may rupture depending on the temperature of the

metal, the degree of load applied and the length of time that it is applied. All three of these

factors determine a metal's ability to resist creep, and therefore, its creep strength.

1.6.9 Oxidation Resistance - The atoms of metal have a tendency to unite with oxy-

gen in the air to form oxide compounds, the most visible being rust and scale. In some

metals, these oxides will adhere very tightly to the skin of the metal and effectively seal it

from further oxidation as is evident in stainless steel. These materials have high oxidation

resistance. In other metals, the bond is very loose, creating a situation where the oxides

will flake off, and the metal gradually deteriorates as the time of exposure is extended.

1.6.10 Hardness Test - The resistance of a metal to indentation is a measure of its

hardness and an indication of the materials's strength. To test for hardness, a fixed load

forces an indenter into the test material (Figure 7). The depth of the penetration or the size

of the impression is measured. The measurement is converted into a hardness number

through the use of a variety of established tables. The most common tables are the Brinell,

Vickers, Knoop and Rockwell. The Rockwell is further divided into different scales, and

FIGURE 7

HARDNESS TEST SHAPE OF INDENTER INDENTER DESCRIPTION

ROCKWELL

A DiamondC ConeD

B 1/16 in. DiameterF Steel SphereG

1/8 in. DiameterE Steel Sphere

10 mm Sphere of SteelBRINNELL or Tungsten Carbide

VICKERS Diamond Pyramid

KNOOP Diamond Pyramid

}}

Types of Indenters - Hardness Tests


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LESSON I, PART A

depending on the material being tested, the shape of the indenter and the load applied, the

conversion tables may differ. For example, a material listed as having a hardness of Rb or

Rc means its hardness has been determined from the Rockwell "B" scale or the Rockwell

"C" scale.

1.6.11 Coefficient of Expansion - All metals expand when heated and contract when

cooled. This dimensional change is related to the crystalline structure and will vary with

different materials. The different expansion and contraction rates are expressed numeri-

cally by a coefficient of thermal expansion. When two different metals are heated to the

same temperature and cooled at the same rate, the one with the higher numerical coeffi-

cient will expand and contract more than the one with the lesser coefficient.

1.6.12 Thermal Conductivity - Some metals will absorb and transmit heat more readily

than others. They are categorized as having high thermal conductivity. This characteristic

contributes to the fact that some metals will melt or undergo transformations at much lower

temperatures than others.

1.7 EFFECTS OF THE ALLOYING ELEMENTS

Alloying is the process of adding a metal or a nonmetal to pure metals such as copper,

aluminum or iron. From the time it was discovered that the properties of pure metals could

be improved by adding other elements, alloy steel has increased by popularity. In fact,

metals that are welded are rarely in their pure state. The major properties that can be

improved by adding small amounts of alloying elements are hardness, tensile strength,

ductility and corrosion resistance. Common alloying elements and their effect on the

properties of metals are as follows:

1.7.1 Carbon - Carbon is the most effective, most widely used and lowest in cost

alloying element available for increasing the hardness and strength of metal. An alloy

containing up to 1.7% carbon in combination with iron is known as steel, whereas the

combination above 1.7% carbon is known as cast iron. Although carbon is a desirable

alloying element, high levels of it can cause problems; therefore, special care is required

when welding high carbon steels and cast iron.

1.7.2 Sulphur - Sulphur is normally an undesirable element in steel because it causes

brittleness. It may be deliberately added to improve the machinability of the steel. The

sulphur causes the

machine chips to break rather than form long curls and clog the machine. Normally, every

effort is made to reduce the sulphur content to the lowest possible level because it can


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LESSON I, PART A

create welding difficulties.

1.7.3 Manganese - Manganese in contents up to 1% is usually present in all low alloy

steels as a deoxidizer and desulphurizer. That is to say, it readily combines with oxygen

and sulphur to help negate the undesirable effect these elements have when in their natu-

ral state. Manganese also increases the tensile strength and hardenability of steel.

1.7.4 Chromium - Chromium, in combination with carbon, is a powerful hardening

alloying element. In addition to its hardening properties, chromium increases corrosion

resistance and the strength of steel at high temperatures. Chromium is the primary alloying

element in stainless steel.

1.7.5 Nickel - The greatest single property of steel that is improved by the presence of

nickel is its ductility or notch toughness. In this respect, it is the most effective of all alloy-

ing elements in improving a steel's resistance to impact at low temperatures. Electrodes

with high nickel content are used to weld cast iron materials. Nickel is also used in combi-

nation with chromium to form a group known as austenitic stainless steel.

1.7.6 Molybdenum - Molybdenum strongly increases the depth of the hardening

characteristic of steel. It is quite often used in combination with chromium to improve the

strength of the steel at high temperatures. This group of steels is usually referred to as

chrome-moly steels.

1.7.7 Silicon - Silicon is usually contained in steel as a deoxidizer. Silicon will add

strength to steel but excessive amounts can reduce the ductility. Additional amounts of

silicon are sometimes added to welding electrodes to increase the fluid flow of weld metal.

1.7.8 Phosphorus - Phosphorus is considered a harmful residual element in steel

because it greatly reduces ductility and toughness. Efforts are made to reduce it to its very

lowest levels; however, phosphorus is added in very small amounts to some steels to

increase strength.

1.7.9 Aluminum - Aluminum is primarily used as a deoxidizer in steel. It may also be

used in very small amounts to control the size of the grains.

1.7.10 Copper - Copper contributes greatly to the corrosion resistance of carbon steel

by retarding the rate of rusting at room temperature, but high levels of copper can cause

welding difficulties.


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1.7.11 Columbium - Columbium is used in austenitic stainless steel to act as a stabi-

lizer. Since the carbon in the stainless steel decreases the corrosion resistance, a means

of making carbon ineffective must be found. Columbium has a greater affinity for carbon

than chromium, leaving the chromium free for corrosion protection.

1.7.12 Tungsten - Tungsten is used in steel to given strength at high temperatures.

Tungsten also joins with carbon to form carbides that are exceptionally hard, and therefore

have exceptional resistance to wear.

1.7.13 Vanadium - Vanadium helps keep steel in the desirable fine grain condition after

heat treatment. It also helps increase the depth of hardening and resists softening of the

steel during tempering treatments.

1.7.14 Nitrogen - Usually, efforts are made to eliminate hydrogen, oxygen and nitrogen

from steel because their presence can cause brittleness. Nitrogen has the ability to form

austenitic structures; therefore, it is sometimes added to austenitic stainless steel to reduce

the amount of nickel needed, and therefore, the production costs of that steel.

1.7.15 Alloying Elements Summary - It should be understood that the addition of

elements to a pure metal may influence the crystalline form of the resultant alloy. If a pure

metal has allotropic characteristics (the ability of a metal to change its crystal structure) at a

specific temperature, then that characteristic will occur over a range of temperatures with

the alloyed metal. The range in which the change takes place may be wide or narrow,

depending on the alloys and the quantities in which they are added. The alloying element

may also effect the crystalline changes by either suppressing the appearance of certain

crystalline forms or even by creating entirely new forms. All these transformations induced

by alloying elements are dependent on heat input and cooling rates. These factors are

closely controlled at the steel mill, but since the welding operation involves a nonuniform

heating and cooling of metal, special care is often needed in the welding of low and high

alloy steel.


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LESSON I, PART B

1.8 ELECTRICITY FOR WELDING

1.8.1 Principles of Electricity - Arc welding is a method of joining metals accom-

plished by applying sufficient electrical pressure to an electrode to maintain a current path

(arc) between the electrode and the work piece. In this process, electrical energy is

changed into heat energy, bringing the metals to a molten state; whereby they are joined.

The electrode (conductor) is either melted and added to the base metal or remains in its

solid state. All arc welding utilizes the transfer of electrical energy to heat energy, and to

understand this principle, a basic knowledge of electricity and welding power sources is

necessary.

1.8.1.1 The three basis principles of static electricity are as follows:

1. There are two kinds of electrical charges in existence - negative and positive.

2. Unlike charges attract and like charges repel.

3. Charges can be transferred from one place to another.

1.8.1.2 Science has established that all matter is made up of atoms and each atom

contains fundamental particles. One of these particles is the electron, which has the ability

to move from one place to another. The electron is classified as a negative electrical

charge. Another particle, about 1800 times as heavy as the electron, is the proton and

under normal conditions the proton will remain stationary.

1.8.1.3 Material is said to be in an electrically uncharged state when its atoms contain anequal number of positive charges (protons) and negative charges (electrons). This balance

is upset when pressure forces the electrons to move from atom to atom. This pressure,

sometimes referred to as electromotive force, is commonly known as voltage. It should benoted that voltage that does not move through a conductor, but without voltage, there would

be no current flow. For our purposes, it is easiest to think of voltage as the electrical

pressure that forces the electrons to move.

1.8.1.4 Since we know that like charges repel and unlike charges attract, the tendency is

for the electrons to move from a position of over-supply (negative charge) to an atom that

lacks electrons (positive charge). This tendency becomes reality when a suitable path is

provided for the movement of the electrons. The transfer of electrons from a negative to a

positive charge throughout the length of a conductor constitutes an electrical current. The

rate that current flows through a conductor is measured in amperes and the word ampere

is often used synonymously with the term current. To give an idea of the quantities of

electrons that flow through a circuit, it has been theoretically established that one ampere

equals 6.3 quintillion (6,300,000,000,000,000,000) electrons flowing past a fixed point in a

conductor every second.


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1.8.1.5 Different materials vary in their ability to transfer electrons. Substances, such as

wood and rubber, have what is called a tight electron bond and their atoms greatly resist

the free movement of electrons. Such materials are considered poor electrical conductors.

Metals, on the other hand, have large amounts of electrons that transfer freely. Their

comparatively low electrical resistance classifies them as good electrical conductors.

1.8.1.6 Electrical resistance is primarily due to the reluctance of atoms to give up their

electron particles. It may also be thought of as the resistance to current flow.

1.8.1.7 To better understand the electrical terms discussed above, we might compare

the closed water system with the electrical diagram shown in Figure 8. You can see that as

the pump is running, the water will move in the direction of the arrows. It moves because

pressure has been produced and that pressure can be likened to voltage in an electrical

circuit. The pump can be compared to a battery or a DC generator. The water flows

through the system at a certain rate. This flow rate in an electrical circuit is a unit of

measure known as the ampere. The small pipe in the fluid circuit restricts the flow rate and

can be likened to a resistor. This unit resistance is known as the ohm. If we close the

valve in the fluid circuit, we stop the flow, and this can be compared to opening a switch in

an electrical circuit.

1.8.2 Ohm's Law - Resistance is basic to electrical theory and to understand this

principle, we must know the Ohm's Law, which is stated as follows: In any electrical circuit,

the current flow in amperes is directly proportional to the circuit voltage applied and in-

versely proportional to the circuit resistance. Directly proportional means that even though

the voltage and amperage may change, the ratio of their relationship will not. For example,

if we have a circuit of one volt and three amps, we say the ratio is one to three. Now if we

increase the volts to three, our amperage will increase proportionately to nine amps. As

can be seen, even though the voltage and amperage changed in numerical value, their

ratio did not. The term "inversely proportional" simply means that if the resistance is

FIGURE 8

VALVE

SWITCH

RESISTOR10 OHM

BATTERY12 VOLT

ELECTRICAL DIAGRAM

SMALL PIPEPUMP

CLOSED WATER SYSTEM

LARGEPIPE


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LESSON I, PART B

doubled, the current will be reduced to one-half. Ohm's Law can be stated mathematically

with this equation:

I = E ÷ R or E = I × R or R = E ÷ I

(E = Volts, I = Amperes, R = Resistance (Ohms))

1.8.2.1 The equation is easy to use as seen in the following problems:

1) A 12 volt battery has a built-in resistance of 10 ohms. What is the amperage?

12 ÷ 10 = 1.2 amps

2) What voltage is required to pass 15 amps through a resistor of 5 ohms?

15 × 5 = 75 volts

3) When the voltage is 80 and the circuit is limited to 250 amps, what is the valueof the resistor?

80 ÷ 250 = .32 ohms

1.8.2.2 The theory of electrical resistance is of great importance in the arc welding

process for it is this resistance in the air space between the electrode and the base metal

that contributes to the transfer of electrical energy to heat energy. As voltage forces the

electrons to move faster, the energy they generate is partially used to overcome the

resistance created by the arc gap. This energy becomes evident as heat. In the welding

process, the temperature increases to the point where it brings metals to a molten state.

1.8.3 Electrical Power - The word "watt" is another term frequently encountered in

electrical terminology. When we pay our electrical bills, we are actually paying for the

power to run our electrical appliances, and the watt is a unit of power. It is defined as the

amount of power required to maintain a current of one ampere at a pressure of one volt.

The circuit voltage that comes into your home is a constant factor, but the amperage drawn

from the utility company depends on the number of watts required to run the electrical

appliance. The watt is figured as a product of volts times amperes and is stated math-

ematically with the following equation:

W =E × I E = W ÷ I I = W ÷ E

(W = Watts, E = Volts, I = Amperes)

1.8.3.1 The amperage used by an electrical device can be calculated by dividing the

watts rating of the device by the primary voltage for which it is designed.


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LESSON I, PART B

1.8.3.2 For example, if an appliance is designed for the common household primary

voltage of 115 and the wattage stamped on the appliance faceplate is 5, then the

amperage drawn by the appliance when in operation is determined as shown:

5 ÷ 115 = .04 amperes

1.8.3.3 Kilowatt is another term common in electrical usage. The preface "kilo" is a

metric designation that means 1,000 units of something; therefore, one kilowatt is 1,000

watts of power.

1.8.4 Power Generation - Electrical energy is supplied either as direct current (DC) or

alternating current (AC). With direct current, the electron movement within the conductor is

in one direction only. With alternating current, the electron flow reverses periodically. Al-

though some types of electrical generators will produce current directly (such as batteries,

dry cells, or DC generators), most direct current is developed from alternating current.

1.8.4.1 Through experimentation, it was discovered that when a wire is moved through a

magnetic field, an electrical current is induced into the wire, and the current is at its

maximum when the motion of the conductor is at right

angles to the magnetic lines of force. The sketch

in Figure 9 will help to illustrate this principle.

1.8.4.2 If the conductor is moved upwards in

the magnetic field between the N and S poles,

the galvanometer needle will deflect plus (+).

Likewise, if the conductor is moved downwards

the needle will deflect minus (-). With this

principle of converting mechanical energy into

electrical energy understood, we can apply it to

the workings of an AC generator.

1.8.4.3 Figure 10 is a simplified sketch of an AC

generator. Starting at 0° rotation, the coil wire is moving

parallel to the magnetic lines of force and cutting none of them. Therefore, no current is

being induced into the winding.

1.8.4.4 From 0° to 90° rotation, the coil wire cuts an increasing number of magnetic lines

of force and reaches the maximum number at 90° rotation. The current increases to the

maximum because the wire is now at right angles to the lines of force.

FIGURE 9

GALVANOMETER

ELECTRO-MAGNETICINDUCTION


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LESSON I, PART B

1.8.4.5 From 90° to 180° rotation, the coil wire cuts a diminishing number of lines of

force and at 180° again reaches zero.

1.8.4.6 From 180° to 270°, the current begins to rise again but in the opposite direction

because now the wire is in closer proximity to the opposite pole.

1.8.4.7 One cycle is completed as the coil wire moves from 270° to 0° and the current

again drops to zero.

1.8.4.8 With the aid of a graph, we can visualize the rate at which the lines of force are

cut throughout the cycle. If we plot the current versus degree of rotation, we get the

familiar sine wave as seen in Figure 11.

1.8.4.9 With this sine wave, we can

see that one complete cycle of

alternating current comprises one

positive and one negative wave

(negative and positive meaning

electron flow in opposing directions).

The frequency of alternating current is

the number of such complete cycles

per second. For most power

applications, 60 cycles per second (60

Hertz) is the standard frequency in

North America.

FIGURE 10

CONTACTS

N N

N N

S S

S

ROTATING COILOR ARMATURE

PERMANENT MAGNETSOR FIELD COILS

S

N

S

270°180°

0° 90°

BASIC AC POWER GENERATION

FIGURE 11

MAXIMUM (+)

MAXIMUM (–)

0° 90° 180° 270° 360°START 1/4 TURN 1/2 TURN 3/4 TURN FULL TURN

(+)

(–)

000

ONE CYCLE - ALTERNATING CURRENT


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LESSON I, PART B

1.8.4.10 Some welders use a three-phase AC supply. Three-phase is simply three

sources of AC power as identical voltages brought in by three wires, the three voltages or

phases being separated by 120 electrical degrees. If

the sine wave for the three phases are plotted on one

line, they will appear as shown in Figure 12.

1.8.4.11 This illustrates that three-phase power is

smoother than single-phase because the overlapping

three phases prevent the current and voltage from

falling to zero 120 times a second, thereby producing a

smoother welding arc.

1.8.4.12 Since all shops do not have three-phase power, welding machines for both

single-phase and three-phase power are available.

1.8.5 Transformers - The function of a transformer is to increase or decrease voltage

to a safe value as the conditions demand. Common household voltage is usually 115 or

230 volts, whereas industrial power requirements may be 208, 230, 380, or 460 volts.

Transmitting such relatively low voltages over long distances would require a conductor of

enormous and impractical size. Therefore, power transmitted from a power plant must be

stepped up for long distance transmission and then stepped down for final use

1.8.5.1 As can be seen in Figure 13, the voltage is generated at the power plant at

13,800 volts. It is increased, transmitted over long distances, and then reduced in steps for

the end user. If power supplied to a transformer circuit is held steady, then secondary

current (amperes) decreases as the primary voltage increases, and conversely, secondary

current increases as primary voltage decreases. Since the current flow (amperes)

determines the wire or conductor size, the high voltage line may be of a relatively small

diameter.

FIGURE 12

120°

1 CYCLE

THREE PHASE AC

240°

0°

FIGURE 13

POWER TRANSMISSION

13,800 V

POWERPLANT STEP

UP

287,000V

HIGH VOLTAGE

300 MILES

STEPDOWN

132,000 V

34,000 V

4,600V

208V230V460V

FINALUSE


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LESSON I, PART B

1.8.5.2 The transformer in a welding machine performs much the same as a large power

plant transformer. The primary voltage coming into the machine is too high for safe

welding. Therefore, it is stepped down to a useable voltage. This is best illustrated with an

explanation of how a single transformer works.

1.8.5.3 In the preceding paragraphs, we have found than an electrical current can be

induced into a conductor when that conductor is moved through a magnetic field to

produce alternating current. If this alternating current is passed through a conductor, a

pulsating magnetic field will surround the exterior of that conductor, that is the magnetic

field will build in intensity through the first 90 electrical degrees, or the first cycle. From that

point, the magnetic field will decay during the next quarter cycle until the voltage or current

reaches zero at 180 electrical degrees. Immediately, the current direction reverses and the

magnetic field will begin to build again until it reaches a maximum at 270 electrical degrees

in the cycle. From that point the current and the magnetic field again begin to decay until

they reach zero at 360 electrical degrees, where the cycle begins again.

1.8.5.4 If that conductor is wound around a material with high magnetic permeability

(magnetic permeability is the ability to accept large amounts of magnetic lines of force)

such as steel, the magnetic field permeates that core. See

Figure 14. This conductor is called the primary coil, and if

voltage is applied to one of its terminals and the circuit is

completed, current will flow. When a second coil is wound

around that same steel core, the energy that is stored in

this fluctuating magnetic field in the core is induced into

this secondary coil.

1.8.5.5 It is the build-up and collapse of this magnetic

field that excite the electrons in the secondary coil of the

transformer. This causes an electrical current of the same frequency as the primary coil to

flow when the secondary circuit is completed by striking the welding arc. Remember that

all transformers operate only on alternating current.

1.8.5.6 A simplified version of a welding transformer is schematically shown in Figure 15.

This welder would operate on 230 volts input power and the primary winding has 230 turns

of wire on the core. We need 80 volts for initiating the arc in the secondary or welding

circuit, thus we have 80 turns of wire in the secondary winding of the core. Before the arc

is struck, the voltage between the electrode and the work piece is 80 volts. Remember that

no current (amperage) flows until the welding circuit is completed by striking the arc.

FIGURE 14

STEEL CORE

PRIMARYCOIL

SECONDARYCOIL

80 V

80TURNS

460 V

460TURNS

BASIC TRANSFORMER


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LESSON I, PART B

1.8.5.7 Since the 80 volts

necessary for initiating the arc

is too high for practical

welding, some means must be

used to lower this voltage to a

suitable level. Theoretically, a

variable resistor of the proper

value could be used as an

output control since voltage is

inversely proportional to

resistance as we saw when studying Ohm's Law. Ohm's Law also stated that the

amperage is directly proportional to the voltage. This being so, you can see that adjusting

the output control will also adjust the amperage or welding current.

1.8.5.8 After the arc is initiated and current begins to flow through the secondary or

welding circuit, the voltage in that circuit will be 32 volts because it is then being controlled

by the output control.

1.8.6 Power Requirements - We can make another calculation by looking back at

Figure 15, and that is power consumption. Earlier, we explained that the watt was the unit

of electrical power and can be calculated by the formula:

Watts = Volts × Amperes

1.8.6.1 From Figure 15, we can see that the instantaneous power in the secondary

circuit is:

Watts = 32 × 300

Watts = 9600 Watts

1.8.6.2 The primary side of our transformer must be capable of supplying 9600 watts

also (disregarding losses due to heating, power factor, etc.), so by rearranging the formula,

we can calculate the required supply line current or amperage:

Amperage = Watts ÷ Volts

A = 9600 ÷ 230 = 41.74 Amps

1.8.6.3 This information establishes the approximate power requirements for the welder,

and helps to determine the input cable and fuse size necessary.

FIGURE 15

9600 WATTS 9600 WATTS

230 TURNS 80 TURNS

80OCV

OUTPUTCONTROL

230VOLTS PRIMARY SECONDARY

41.74AMPS

SIMPLIFIED WELDING TRANSFORMER

32 VOLTS300 AMPS


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LESSON I, PART B

1.8.7 Rectifying AC to DC - Although much welding is accomplished with AC welding

power sources, the majority of industrial welding is done with machines that produce a

direct current arc. The commercially produced AC

power that operates the welding machine

must then be changed (rectified) to direct

current for the DC arc. This is accom-

plished with a device called a rectifier.

Two types of rectifiers have been used

extensively in welding machines, the

old selenium rectifiers and the more

modern silicon rectifiers, often referred

to as diodes. See Figure 16.

1.8.7.1 The function of a rectifier in the

circuit can best be shown by the use of the

AC sine wave. With one diode in the circuit,

half-wave rectification takes place as shown

in Figure 17.

1.8.7.2 The negative half-wave is simply cut off and a pulsating DC is produced. During

the positive half-cycle, current is allowed to flow through the rectifier. During the negative

half-cycle, the current is blocked. This produces a DC composed of 60 positive pulses per

second.

1.8.7.3 By using four rectifiers connected in a

certain manner, a bridge rectifier is created, producing

full wave rectification. The bridge rectifier results in

120 positive half-cycles per second, producing a

considerably smoother direct current than half-wave

rectification. See Figure 18.

1.8.7.4 Three-phase AC can be rectified to

produce an even smoother DC than single-phase

AC. Since three-phase AC power produces three

times as many half-cycles per second as single-

phase power, a relatively smooth DC voltage

results as shown in Figure 19.

SINGLE PHASE HALF WAVE RECTIFICATION

FIGURE 17

FIGURE 16

SILICON RECTIFIERSELENIUM RECTIFIER

SINGLE PHASE FULL WAVE RECTIFICATION

FIGURE 18

1 CYCLE

3 PHASE FULL WAVE RECTIFICATIONFIGURE 19


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LESSON I, PART B

1.9 CONSTANT CURRENT OR CONSTANT VOLTAGE

Welding power sources are designed in many sizes and shapes. They may supply either

AC or DC, or both, and they may have various means of controlling their voltage and

amperage output. The reasons for this is that the power source must be capable of

producing the proper arc characteristics for the welding process being used. A power

source that produces a satisfactory arc when welding with coated electrodes will be less

than satisfactory for welding with solid and flux cored wires.

1.9.1 Constant Current Characteristics - Constant current power sources are used

primarily with coated electrodes. This type of power source has a relatively small change in

amperage and arc power for a corresponding relatively large change in arc voltage or arc

length, thus the name constant current. The characteristics of this power source are best

illustrated by observing a graph that plots the volt-

ampere curve. As can be seen in Figure 20, the

curve of a constant current machine drops down-

ward rather sharply and for this reason, this type of

machine is often called a "drooper."

1.9.1.1 In welding with coated electrodes, the

output current or amperage is set by the operator

while the voltage is designed into the unit. The

operator can vary the arc voltage somewhat by

increasing or decreasing the arc length. A slight

increase in arc length will cause an increase in arc

voltage and a slight decrease in amperage. A slight

decrease in arc length will cause a decrease in arc

voltage and a slight increase in amperage.

1.9.2 Constant Voltage Characteristics - Constant voltage power sources, also

known as constant potential, are used in welding with solid and flux cored electrodes, and

as the name implies, the voltage output remains relatively constant. On this type of power

source, the voltage is set at the machine and amperage is determined by the speed that

the wire is fed to the welding gun. Increasing the wire feed speed increases the amperage.

Decreasing the wire feed speed decreases the amperage.

1.9.2.1 Arc length plays an important part in welding with solid and flux cored electrodes,

just as it does in welding with a coated electrode. However, when using a constant voltage

power source and a wire feeder that delivers the wire at a constant speed, arc length

caused by operator error, plate irregularities, and puddle movement are automatically

34V - 290A

32V - 300 A

30V - 308 A

VOLT / AMPERE CURVECONSTANT CURRENT

100 200 300AMPERES

CONSTANT CURRENT VOLT / AMPERE CURVE

FIGURE 20

80

70

60

50

40

30

20

10

VOLTS


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LESSON I, PART B

compensated for by the characteristics of this process. To understand this, keep in mind

that with the proper voltage setting, amperage setting, and arc length, the rate that the wire

melts is dependent upon the amperage. If the amperage decreases, this melt-off rate

decreases and if the amperage increases, so does the melt-off rate.

1.9.2.2 In Figure 21, we see that condition #2 produces the desired arc length, voltage,

and amperage. If the arc length is increased as in #1, the voltage increases slightly; the

amperage decreases considerably, and therefore, the melt-off rate of the wire decreases.

The wire is now feeding faster than it is melting

off. This condition will advance the end of the

wire towards the work piece until the proper arc

length is reached where again, the melt-off rate

equals the feeding rate. If the arc length is

decreased as in #3, the voltage drops off

slightly, the amperage is increased

considerably, and the melt-off rate of the wire

increases. Since the wire is now melting off

faster than it is being fed, it melts back to the

proper arc length where the melt-off rate

equals the feeding rate. This is often referred

to as a self-adjusting arc. These automatic

corrections take place in fractions of a second,

and usually without the operator being aware

of them.

1.9.2.3 There are a variety of different welding machines, each with its own unique

internal design. Our purpose is not to detail the function of each part of the machine, but to

emphasize that their main difference is in the way they control the voltage and amperage

output.

1.9.3 Types of Welding Power Sources - A great variety of welding power sources

are being built today for electric arc welding and we shall mention some of the major types

briefly. Welding power sources can be divided into two main categories: static types and

rotating types.

1.9.3.1 Static Types - Static type power sources are all of those that use commercially

generated electrical power to energize a transformer that, in turn, steps the line voltage

down to useable welding voltages. The two major categories of static power sources are

the transformer type and the rectifier type.

1 2 3

VOLTS

40

30

20

10

100 200 300 400AMPERES

VOLT / AMPERE CURVE - CONSTANT VOLTAGEFIGURE 21


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LESSON I, PART B

1.9.3.1.1 The transformer type produce only alternating current. They are commonly

called "Welding Transformers." All AC types utilize single-phase primary power and are of

the constant current type.

1.9.3.1.2 The rectifier types are commonly called "Welding Rectifiers" and produce DC or,

AC and DC welding current. They may utilize either single phase or three phase input

power. They contain a transformer, but rectify the AC or DC by the use of selenium

rectifiers, silicon diodes or silicon controlled rectifiers. Available in either the constant

current or the constant voltage type, some manufacturers offer units that are a combination

of both and can be used for coated electrode welding, non-consumable electrode welding

and for welding with solid or flux cored wires.

1.9.3.2 Rotating Types - Rotating type power sources may be divided into two classifi-

cations:1. Motor-Generators

2. Engine Driven

1.9.3.2.1 Motor-generator types consist of an electric motor coupled to a generator or

alternator that produces the desired welding power. These machines produced excellent

welds, but due to the moving parts, required considerable maintenance. Few, if any, are

being built today.

1.9.3.2.2 Engine driven types consist of a gasoline or diesel engine coupled to a generator

or alternator that produces the desired welding power. They are used extensively on jobs

beyond commercial power lines and also as mobile repair units. Both rotating types can

deliver either AC or DC welding power, or a combination of both. Both types are available

as constant current or constant voltage models.

1.9.4 Power Source Controls - Welding power sources differ also in the method of

controlling the output current or voltage. Output may be controlled mechanically as in

machines having a tapped reactor, a moveable shunt or diverter, or a moveable coil. Elec-

trical types of controls, such as magnetic amplifiers or saturable reactors, are also utilized

and the most modern types, containing silicon controlled rectifiers, give precise electronic

control.

1.9.4.1 A detailed discussion of the many types of welding power sources on the market

today is much too lengthy a subject for this course, although additional information on the

type of power sources for the various welding processes will be covered in Lesson II.

1.9.4.2 Excellent literature is available from power source manufacturers, however, and

should be consulted for further reference.


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LESSON I, GLOSSARY

APPENDIX A

LESSON I - GLOSSARY OF TERMS

AISI — American Iron and Steel Institute

Allotropic — A material in which the atoms are capable of transforming into two

or more crystalline structures at different temperatures.

Alternating — An electrical current which alternately travels in either direction in a

Current conductor. In 60 cycles per second (60 Hz) AC, the frequency

used in the U.S.A., the current direction reverses 120 times every

second.

Ampere — Unit of electrical rate of flow. Amperage is commonly referred to as

the “current” in an electrical circuit.

ASME — American Society of Mechanical Engineers

ASTM — American Society for Testing and Materials

Atom — The smallest particle of an element that posses all of the

characteristics of that element. It consists of protons, neutrons,

and electrons.

Carbon Steel — (Sometimes referred to as mild steel.) An alloy of iron and carbon.

Carbon content is usually below 0.3%.

Conductor — A material which has a relatively large number of loosely bonded

electrons which may move freely when voltage (electrical pressure)

is applied. Metals are good conductors.

Constant Current — (As applied to welding machines.) A welding power source which

will produce a relatively small change in amperage despite

changes in voltage caused by a varying arc length. Used mostly

for welding with coated electrodes.


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LESSON I, GLOSSARY

Constant Voltage — (As applied to welding machines.) A welding power source which

will produce a relatively small change in voltage when the

amperage is changed substantially. Used mostly for welding with

solid or flux cored electrodes.

Direct Current — An electrical current which flows in only one direction in a

conductor. Direction of current is dependent upon the electrical

connections to the battery or other DC power source. Terminals on

all DC devices are usually marked (+) or (-). Reversing the leads

will reverse the direction of current flow.

Electron — Negatively charged particles that revolve around the positively

charged nucleus in an atom.

Ferrous — Containing iron. Example: carbon steel, low alloy steels, stainless

steel.

Hertz — Hertz (Hz) is the symbol which has replaced the term “cycles per

second.” Today, rather than saying 60 cycles per second or simply

60 cycles, we say 60 Hertz or 60 Hz.

High Alloy Steels — Steels containing in excess of 10% alloy content. Stainless steel is

considered a high alloy because it contains in excess of 10%

chromium.

Induced Current orInduction — The phenomena of causing an electrical current to flow through a

conductor when that conductor is subjected to a varying magnetic

field.

Ingot — Casting of steel (weighing up to 200 tons) formed at mill from melt

of ore, scrap limestone, coke, etc.

Insulator — A material which has a tight electron bond, that is, relatively few

electrons which will move when voltage (electrical pressure) is

applied. Wood, glass, ceramics and most plastics are good

insulators.


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LESSON I, GLOSSARY

Kilowatt — 1,000 watts

Low Alloy Steels — Steels containing small amounts of alloying elements (usually 1½%

to 5% total alloy content) which drastically improves their

properties.

Non-Ferrous — Containing no iron. Example: Aluminum, copper, copper alloys.

Ohm — Unit of electrical resistance to current flow.

PhaseTransformation — The changes in the crystalline structure of metals caused by

temperature and time.

Proton — Positively charged particles which are part of the nucleus of atoms.

Rectifier — An electrical device used to change alternating current to direct

current.

SAE — Society of Automotive Engineers

Transformer — An electrical device used to raise or lower the voltage and inversely

change the amperage.

Volt — Unit of electromotive force, or electrical pressure which causes

current to flow in an electrical circuit.

Watt — A unit of electrical power. Watts = Volts x Amperes


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TECHNOLOGY


LESSON IICOMMON ELECTRIC ARC

WELDING PROCESSES




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TABLE OF CONTENTSLESSON II

COMMON ELECTRIC ARC WELDINGPROCESSES

2.1 INTRODUCTION .............................................................................. 1

2.2 SHIELDED METAL ARC WELDING ............................................... 1

2.2.1 Equipment & Operation ..................................................................... 2

2.2.2 Welding Power Sources .................................................................... 2

2.2.3 Electrode Holder................................................................................ 4

2.2.4 Ground Clamp ................................................................................... 4

2.2.5 Welding Cables ................................................................................. 4

2.2.6 Coated Electrodes ............................................................................ 4

2.3 GAS-TUNGSTEN ARC WELDING .................................................. 5

2.3.1 Equipment & Operation ..................................................................... 6

2.3.2 Power Sources .................................................................................. 7

2.3.3 Torches.............................................................................................. 10

2.3.4 Shielding Gases ................................................................................ 11

2.3.5 Electrodes ......................................................................................... 12

2.3.6 Summary ........................................................................................... 13

2.4 GAS METAL ARC WELDING .......................................................... 13

2.4.1 Current Density .................................................................................. 14

2.4.2 Metal Transfer Modes ........................................................................ 15

2.4.3 Equipment and Operation .................................................................. 17

2.4.4 Power Source.................................................................................... 18

2.4.5 Wire Feeder ...................................................................................... 19

2.4.6 Welding Gun ...................................................................................... 20

2.4.7 Shielding Gases ................................................................................ 21

2.4.7.1 Short Circuiting Transfer .................................................... 22

2.4.7.2 Spray Arc Transfer ............................................................ 23



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2.4.7.3 Pulse Spray Transfer ......................................................... 23

2.4.8 Electrodes ......................................................................................... 23

2.5 FLUX CORED ARC WELDING ....................................................... 24

2.5.1 Self-Shielded Process ....................................................................... 24

2.5.2 Gas Shielded Process....................................................................... 25

2.5.3 Current Density .................................................................................. 26

2.5.4 Equipment ......................................................................................... 26

2.5.5 Power Source.................................................................................... 26

2.5.6 Wire Feeder ...................................................................................... 26

2.5.7 Welding Guns .................................................................................... 26

2.5.8 Shielding Gases ................................................................................ 27

2.6 SUBMERGED ARC WELDING ....................................................... 27

2.6.1 Submerged Arc Flux .......................................................................... 28

2.6.2 The Welding Gun ............................................................................... 28

2.6.3 Power Sources .................................................................................. 28

2.6.4 Equipment ......................................................................................... 28

2.6.5 Electrodes ......................................................................................... 29

2.6.6 Summary ........................................................................................... 29

2.7 ELECTROSLAG AND ELECTROGAS WELDING .......................... 30

2.7.1 Electroslag Welding........................................................................... 30

2.7.2 Flux ................................................................................................... 30

2.7.3 Process ............................................................................................. 30

2.7.4 Equipment......................................................................................... 31

2.7.5 Summary .......................................................................................... 31

Appendix A - GLOSSARY OF TERMS ................................................................. 32

TABLE OF CONTENTSLESSON II - Con't.



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LESSON II

COMMON ELECTRIC ARC WELDING PROCESSES

2.1 INTRODUCTION

After much experimentation by others in the early 1800's, an Englishman named Wilde

obtained the first electric welding patent in 1865. He successfully joined two small pieces of

iron by passing an electric current through both pieces producing a fusion weld. Approximately

twenty years later, Bernado, a Russian, was granted a patent for an electric arc welding

process in which he maintained an arc between a carbon electrode and the pieces to be

joined, fusing the metals together as the arc was manually passed over the joint to be welded.

2.1.0.1 During the 1890's, arc welding was accomplished with bare metal electrodes that

were consumed in the molten puddle and became part of the weld metal. The welds were of

poor quality due to the nitrogen and oxygen in the atmosphere forming harmful oxides and

nitrides in the weld metal. Early in the Twentieth Century, the importance of shielding the arc

from the atmosphere was realized. Covering the electrode with a material that decomposed in

the heat of the arc to form a gaseous shield appeared to be the best method to accomplish

this end. As a result, various methods of covering electrodes, such as wrapping and dipping,

were tried. These efforts culminated in the extruded coated electrode in the mid-1920's,

greatly improving the quality of the weld metal and providing what many consider the most

significant advance in electric arc welding.

2.1.0.2 Since welding with coated electrodes is a rather slow procedure, more rapid

welding processes were developed. This lesson will cover the more commonly used electric

arc welding processes in use today.

2.2 SHIELDED METAL ARC WELDING

Shielded Metal Arc Welding*, also known as manual metal arc welding, stick welding, or

electric arc welding, is the most widely used of the various arc welding processes. Welding is

performed with the heat of an electric arc that is maintained between the end of a coated metal

electrode and the work piece (See Figure 1). The heat produced by the arc melts the base

metal, the electrode core rod, and the coating. As the molten metal droplets are transferred

across the arc and into the molten weld puddle, they are shielded from the atmosphere by the

gases produced from the decomposition of the flux coating. The molten slag floats to the top

of the weld puddle where it protects the weld metal from the atmosphere during solidification.


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LESSON II

Other functions of the coating are to provide

arc stability and control bead shape. More

information on coating functions will be

covered in subsequent lessons.

* Shielded Metal Arc Welding (SMAW) is theterminology approved by the AmericanWelding Society.

2.2.1 Equipment & Operation - One

reason for the wide acceptance of the SMAW

process is the simplicity of the necessary equipment.

The equipment consists of the following items. (See

Figure 2)

1. Welding power source

2. Electrode holder

3. Ground clamp

4. Welding cables and connectors

5. Accessory equipment (chipping

hammer, wire brush)

6. Protective equipment (helmet, gloves, etc.)

2.2.2 Welding Power Sources - Shielded metal arc welding may utilize either

alternating current (AC) or direct current (DC), but in either case, the power source selected

must be of the constant current type. This type of power source will deliver a relatively constant

amperage or welding current regardless of arc length variations by the operator (See Lesson I,

Section 1.9). The amperage determines the amount of heat at the arc and since it will remain

relatively constant, the weld beads produced will be uniform in size and shape.

2.2.2.1 Whether to use an AC, DC, or AC/DC power source depends on the type of welding

to be done and the electrodes used. The following factors should be considered:

1. Electrode Selection - Using a DC power source allows the use of a greater range

of electrode types. While most of the electrodes are designed to be used on AC or

DC, some will work properly only on DC.

2. Metal Thickness - DC power sources may be used for welding both heavy

sections and light gauge work. Sheet metal is more easily welded with DC

because it is easier to strike and maintain the DC arc at low currents.

FIGURE 1

CORE ROD

SHIELDINGGASES SOLIDIFIED

SLAG

WELD METAL

WORK PIECE

MOLTENPOOL

SHIELDED METAL ARC WELDING

AC OR DCPOWERSOURCE

ELECTRODE

CABLE

ELECTRODEHOLDER

ELECTRODE

GROUND

CABLEWORK

SHIELDED METAL ARC WELDING CIRCUIT

FIGURE 2


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COATING

© COPYRIGHT 1998 THE ESAB GROUP, INC.

LESSON II

3. Distance from Work - If the distance from the work to the power source is great,

AC is the best choice since the voltage drop through the cables is lower than with

DC. Even though welding cables are made of copper or aluminum (both good

conductors), the resistance in the cables becomes greater as the cable length

increases. In other words, a voltage reading taken between the electrode and the

work will be somewhat lower than a reading taken at the output terminals of the

power source. This is known as voltage drop.

4. Welding Position (See Appendix A - Glossary of Terms) - Because DC may be

operated at lower welding currents, it is more suitable for overhead and vertical

welding than AC. AC can successfully be used for out-of-position work if proper

electrodes are selected.

5. Arc Blow - When welding with DC, magnetic fields are set up throughout the

weldment. In weldments that have varying thickness and protrusions, this magnetic

field can affect the arc by making it stray or fluctuate in direction. This condition is

especially troublesome when welding in corners. AC seldom causes this problem

because of the rapidly reversing magnetic field produced.

2.2.2.2 Combination power sources that produce both AC and DC are available and

provide the versatility necessary to select the proper welding current for the application.

2.2.2.3 When using a DC power source, the question of whether to use electrode negative

or positive polarity arises. Some electrodes operate on both DC straight and reverse polarity,

and others on DC negative or DC positive polarity only. Direct current flows in one direction in

an electrical circuit and the direction of current flow and the composition of the electrode

coating will have a definite effect on the welding arc and weld bead. Figure 3 shows the

connections and effects of straight and reverse polarity.

2.2.2.4 Electrode negative (-) produces welds with shallow penetration; however, the

electrode melt-off rate is high. The weld bead is rather wide and shallow as shown at "A" in

Figure 3. Electrode

positive (+)

produces welds with

deep penetration

and a narrower weld

bead as shown at

"B" in Figure 3.

FIGURE 3

DCPOWER SOURCE

ELECTRODE

DCPOWER SOURCE

ELECTRODE

A

HIGHER BURN-OFF RATE, LESS PENETRATION

DEEP PENETRATION,LOW BURN-OFF RATE

WORK PIECE

B

STRAIGHT POLARITY REVERSE POLARITYWORK PIECE


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LESSON II

2.2.2.5 While polarity affects the penetration and burn-off rate, the electrode coating also

has a strong influence on arc characteristics. Performance of individual electrodes will be

discussed in succeeding lessons.

2.2.3 Electrode Holder - The electrode holder connects to the welding cable and con-

ducts the welding current to the electrode. The insulated handle is used to guide the electrode

over the weld joint and feed the electrode over the weld joint and feed the electrode into the

weld puddle as it is consumed. Electrode holders are available in different sizes and are rated

on their current carrying capacity.

2.2.4 Ground Clamp - The ground clamp is used to connect the ground cable to the work

piece. It may be connected directly to the work or to the table or fixture upon which the work is

positioned. Being a part of the welding circuit, the ground clamp must be capable of carrying

the welding current without overheating due to electrical resistance.

2.2.5 Welding Cables - The electrode cable and the ground cable are important parts of

the welding circuit. They must be very flexible and have a tough heat-resistant insulation.

Connections at the electrode holder, the ground clamp, and at the power source lugs must be

soldered or well crimped to assure low electrical resistance. The cross-sectional area of the

cable must be sufficient size to carry the welding current with a minimum of voltage drop.

Increasing the cable length necessitates increasing the cable diameter to lessen resistance

and voltage drop. The table in Figure 4 lists the suggested American Wire Gauge (AWG)

cable size to be used for various welding currents and cable lengths.

Total Cable Length (Ground Lead Plus Electrode Lead)Up to 50 ft. Up to 100 ft. Up to 250 ft. Up to 500 ft.

Cable Voltage Cable Voltage Cable Voltage Cable VoltageSize Drop Size Drop Size Drop Size Drop

20 to 180 #3 1.8 #2 2.9 #1 5.7 #0 9.1 180 Amps30 to 250 #2 1.8 #1 2.5 #0 5.0 #0 9.9 200 Amps60 to 375 #0 1.7 #0 3.0 #00 5.9 #000 9.3 300 Amps80 to 500 #00 1.8 #000 2.5 #0000 5.0 #0000 9.9 400 Amps

100 to 600 #00 2.0 #0000 2.5 ... ... ... 500 Amps

Voltage drops indicated do not include any drop caused by poor connection, electrode holder, or work metal

WeldingServiceRange

(Amperes)

VoltageDrop

FiguredAt

FIGURE 4

2.2.6 Coated Electrodes - Various types of coated electrodes are used in shielded

metal arc welding. Electrodes used for welding mild or carbon steels are quite different than

those used for welding the low alloys and stainless steels. Details on the specific types will be

covered in subsequent lessons.


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LESSON II

2.3 GAS TUNGSTEN ARC WELDING

Gas Tungsten Arc Welding* is a welding process performed using the heat of an arc

established between a nonconsumable tungsten electrode and the work piece. See Figure 5.

The electrode, the arc, and the area surrounding the molten weld puddle are protected from

the atmosphere by an inert gas shield. The electrode is not consumed in the weld puddle as in

shielded metal arc welding. If a filler metal is

necessary, it is added to the leading

the molten puddle as shown in

2.3.0.1 Gas tungsten arc welding

produces exceptionally clean welds

no slag is produced, the chance

inclusions in the weld metal is

and the finished weld requires

virtually no cleaning. Argon

and Helium, the primary

shielding gases employed,

are inert gases. Inert gases

do not chemically combine

with other elements and

therefore, are used to exclude

the reactive gases, such as oxygen and

nitrogen, from forming compounds that could

be detrimental to the weld metal.

2.3.0.2 Gas tungsten arc welding may be used for welding almost all metals — mild steel,

low alloys, stainless steel, copper and copper alloys, aluminum and aluminum alloys, nickel

and nickel alloys, magnesium and magnesium alloys, titanium, and others. This process is

most extensively used for welding aluminum and stainless steel alloys where weld integrity is of

the utmost importance. Another use is for the root pass (initial pass) in pipe welding, which

requires a weld of the highest quality. Full penetration without an excessively high inside bead

is important in the root pass, and due to the ease of current control of this process, it lends

itself to control of back-bead size. For high quality welds, it is usually necessary to provide an

inert shielding gas inside the pipe to prevent oxidation of the inside weld bead.

* Gas Tungsten Arc Welding (GTAW) is the current terminology approved by the American Welding Society,formerly known as "TIG" (Tungsten Inert Gas) welding.

FIGURE 5

TRAVELDIRECTION

TORCH

SHIELDING GASNOZZLE

INERT GASSHIELD

WORK PIECE

TUNGSTENELECTRODE

ARC

FILLERMETAL

GAS TUNGSTEN ARC WELDING


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LESSON II

2.3.0.3 Gas tungsten arc welding lends itself to both manual and automatic operation. In

manual operation, the welder holds the torch in one hand and directs the arc into the weld joint.

The filler metal is fed manually into the leading edge of the puddle. In automatic applications,

the torch may be automatically moved over a stationary work piece or the torch may be

stationary with the work moved or rotated in relation to the torch. Filler metal, if required, is

also fed automatically.

2.3.1 EQUIPMENT AND OPERATION - Gas tungsten arc welding may be accomplished

with relatively simple equipment, or it may require some highly sophisticated components.

Choice of equipment depends upon the type of metal being joined, the position of the weld

being made, and the quality of the weld metal necessary for the application. The basic equip-

ment consists of the following:

1. The power source

2. Electrode holder (torch)

3. Shielding gas

4. Tungsten electrode

5. Water supply when necessary

6. Ground cable

7. Protective equipment

Figure 6 shows a basic gas tungsten arc welding schematic.

FIGURE 6

REGULATORFLOW METER

GAS HOSE (WATER COOLED ONLY)

TORCH

* COMPOSITE CABLE

WATER COOLER

GAS COOLED ONLY

WELDING CABLE

SHIELDINGGAS SUPPLY

POWERSOURCE WATER

FROMTORCH

WATERTO

TORCH

GROUND CABLE

WORK

* COMPOSITE CABLEGAS COOLED TORCH.CURRENT IN & GAS IN.

WATER COOLED TORCH.CURRENT IN & WATER OUT

GAS TUNGSTEN ARC WELDING CONNECTION SCHEMATIC


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LESSON II

2.3.2 Power Sources - Both AC and DC power sources are used in gas tungsten arc

welding. They are the constant current type with a drooping volt-ampere curve. This type of

power source produces very slight changes in the arc current when the arc length (voltage) is

varied. Refer to Lesson I, Section 1.9.

2.3.2.1 The choice between an AC or DC welder depends on the type and thickness of the

metal to be welded. Distinct differences exist between AC and DC arc characteristics, and if

DC is chosen, the polarity also becomes an important factor. The effects of polarity in GTAW

are directly opposite the effects of polarity in SMAW as described in paragraphs 2.2.2.3

through 2.2.2.5. In SMAW, the distribution of heat between the electrode and work, which

determines the penetration and weld bead width, is controlled mainly by the ingredients in the

flux coating on the electrode. In GTAW where no flux coating exists, heat distribution between

the electrode and the work is controlled solely by the polarity. The choice of the proper welding

current will be better understood by analyzing each type separately. The chart in Figure 7 lists

current recommendations.

FIGURE 7

Material &Thickness DCEN DCEP

ACHigh Freq. Argon Helium Ar/He

AluminumUnder 1/8"Over 1/8"

22 & 3

11

11

23 2

MagnesiumUnder 1/16"Over 1/16"

2 11

11

2

Carbon SteelUnder 1/8"Over 1/8"

11

11 2 3

Stainless SteelUnder 1/8"Over 1/8"

11

11

22

CopperUnder 1/8"Over 1/8"

11 1

1

Nickel AlloysUnder 1/8"Over 1/8"

11

1 32

21

TitaniumUnder 1/8"Over 1/8"

1 12

21

WELDING CURRENT SHIELDING GAS

1. Preferred Choice - Manual Welding2. Preferred Choice - Automatic Welding3. Second Choice - Automatic Welding

CURRENT/SHIELDING GAS SELECTION, TUNGSTEN GAS ARC WELDING


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2.3.2.2 Direct current electrode negative (DCEN) is produced when the electrode is

connected to the negative terminal of the power source. Since the electrons flow from the

electrode to the plate, approximately 70% of the heat of the arc is concentrated at the work,

and approximately 30% at the electrode end. This allows the use of smaller tungsten elec-

trodes that produce a relatively narrow concentrated arc. The weld shape has deep penetra-

tion and is quite narrow. See Figure 8. Direct current electrode negative is suitable for weld-

ing most metals. Magnesium and aluminum have a refractory oxide coating on the surface that

must be physically removed immediately prior to welding if DCSP is to be used.

2.3.2.3 Direct current electrode positive (DCEP) is produced when the electrode is

connected to the positive terminal of the welding power source. In this condition, the electrons

flow from the work to the electrode tip, concentrating approximately 70% of the heat of the arc

at the electrode and 30% at the work. This higher heat at the electrode necessitates using

larger diameter tungsten to prevent it from melting and contaminating the weld metal. Since

the electrode diameter is larger and the heat is less concentrated at the work, the resultant

weld bead is relatively wide and shallow. See Figure 8.

2.3.2.4 Aluminum and magnesium are two metals that have a heavy oxide coating that acts

as an insulator and must be removed before successful welding can take place. Welding with

electrode positive provides a good oxide cleaning action in the arc. If we were to study the

physics of the welding arc, we find that the electric current causes the shielding gas atoms to

lose some of their electrons. Since electrons are negatively charged, these gas atoms now

are unbalanced and have an excessive positive charge. As we learned in Lesson I, unlike

charges attract. These positively charged atoms (or positive ions as they are known in

FIGURE 8

Electrode Oxide HeatPolarity Penetration Cleaning Concentration

Direct Current

Alternating CurrentMedium Penetration

Medium WidthBead

GoodCleans Oxideon Each Half

CycleAlternates BetweenElectrode and Work

Straight PolarityElectrode Negative

DeepPenetration

NarrowBead

Direct Current

Reverse PolarityElectrode Positive

Shallow Penetration

Wide BeadMaximum

None AtWork

AtElectrode

GAS IONS

+

_

ELECTRONFLOW

_

_

+

+

EFFECTS OF CURRENT TYPE - GAS TUNGSTEN ARC WELDING


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chemical terminology) are attracted to the negative pole, in this case the work, at high velocity.

Upon striking the work surface, they dislodge the oxide coating permitting good electrical

conductivity for the maintenance of the arc, and eliminate the impurities in the weld metal that

could be caused by these oxides.

2.3.2.5 Direct current electrode positive is rarely used in gas-tungsten arc welding. Despite

the excellent oxide cleaning action, the lower heat input in the weld area makes it a slow

process, and in metals having higher thermal conductivity, the heat is rapidly conducted away

from the weld zone. When used, DCEP is restricted to welding thin sections (under 1/8") of

magnesium and aluminum.

2.3.2.6 Alternating current is actually a combination of DCEN and DCEP and is widely

used for welding aluminum. In a sense, the advantages of both DC processes are combined,

and the weld bead produced is a compromise of the two. Remember that when welding with

60 Hz current, the electron flow from the electrode tip to the work reverses direction 120 times

every second. Thereby, the intense heat alternates from electrode to work piece, allowing the

use of an intermediate size electrode. The weld bead is a compromise having medium

penetration and bead width. The gas ions blast the oxides from the surface of aluminum and

magnesium during the positive half cycle. Figure 8 illustrates the effects of the different types

of current used in gas-tungsten arc welding.

2.3.2.7 DC constant current power sources - Constant current power sources, used for

shielded metal arc welding, may also be used for gas-tungsten arc welding. In applications

where weld integrity is not of utmost importance, these power sources will suffice. With

machines of this type, the arc must be initiated by touching the tungsten electrode to the work

and quickly withdrawing it to maintain the proper arc length. This starting method

contaminates the electrode and blunts the point which has been grounded on the electrode

end. These conditions can cause weld metal inclusions and poor arc direction. Using a

power source designed for gas tungsten arc welding with a high frequency stabilizer will

eliminate this problem. The electrode need not be touched to the work for arc initiation.

Instead, the high frequency voltage, at very low current, is superimposed onto the welding

current. When the electrode is brought to within approximately 1/8 inch of the base metal, the

high frequency ionizes the gas path, making it conductive and a welding arc is established.

The high frequency is automatically turned off immediately after arc initiation when using direct

current.

2.3.2.8 AC Constant Current Power Source - Designed for gas tungsten arc welding,

always incorporates high frequency, and it is turned on throughout the weld cycle to maintain a

stable arc. When welding with AC, the current passes through 0 twice in every cycle and the


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arc must be reestablished each time it does so. The oxide coating on metals, such as

aluminum and magnesium, can act much like a rectifier as discussed in Lesson I. The positive

half-cycle will be eliminated if the arc does not reignite, causing an unstable condition.

Continuous high frequency maintains an ionized path for the welding arc, and assures arc re-

ignition each time the current changes direction. AC is extensively used for welding aluminum

and magnesium.

2.3.2.9 AC/DC Constant Current Power Sources - Designed for gas tungsten arc

welding, are available, and can be used for welding practically all metals. The gas tungsten

arc welding process is usually chosen because of the high quality welds it can produce. The

metals that are commonly welded with this process, such as stainless steel, aluminum and

some of the more exotic metals, cost many times the price of mild steel; and therefore, the

power sources designed for this process have many desirable features to insure high quality

welds. Among these are:

1. Remote current control, which allows the operator to control welding amperage

with a hand control on the torch, or a foot control at the welding station.

2. Automatic soft-start, which prevents a high current surge when the arc is

initiated.

3. Shielding gas and cooling water solenoid valves, which automatically control

flow before, during and for an adjustable length of time after the weld is completed.

4. Spot-weld timers, which automatically control all elements during each

spot-weld cycle.

Other options and accessories are also available.

2.3.2.10 Power sources for automatic welding with complete programmable output are also

available. Such units are used extensively for the automatic welding of pipe in position. The

welding current is automatically varied as the torch travels around the pipe. Some units

provide a pulsed welding current where the amperage is automatically varied between a low

and high several times per second. This produces welds with good penetration and improved

weld bead shape.

2.3.3 Torches - The torch is actually an electrode holder that supplies welding current to

the tungsten electrode, and an inert gas shield to the arc zone. The electrode is held in a

collet-like clamping device that allows adjustment so that the proper length of electrode pro-

trudes beyond the shielding gas cup. Manual torches are designed to accept electrodes of 3


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inch or 7 inch lengths. Torches may be either air or water-cooled. The air-cooled types actu-

ally are cooled to a degree by the shielding gas that is fed to the torch head through a compos-

ite cable. The gas actually surrounds the copper welding cable, affording some degree of

cooling. Water-cooled torches are usually used for applications where the welding current

exceeds 200 amperes. The water inlet hose is connected to the torch head. Circulating

around the torch head, the water leaves the torch via the current-in hose and cable assembly.

Cooling the welding cable in this manner allows the use of a smaller diameter cable that is

more flexible and lighter in weight.

2.3.3.1 The gas nozzles are made of ceramic materials and are available in various sizes

and shapes. In some heavy duty, high current applications, metal water-cooled nozzles are

used.

2.3.3.2 A switch on the torch is used to energize the electrode with welding current and start

the shielding gas flow. High frequency current and water flow are also initiated by this switch if

the power source is so equipped. In many installations, these functions are initiated by a foot

control that also is capable of controlling the welding current. This method gives the operator

full control of the arc. The usual welding method is to start the arc at a low current, gradually

increase the current until a molten pool is achieved, and welding begins. At the end of the

weld, current is slowly decreases and the arc extinguished, preventing the crater that forms at

the end of the weld when the arc is broken abruptly.

2.3.4 Shielding Gases - Argon and helium are the major shielding gases used in gas

tungsten arc welding. In some applications, mixtures of the two gases prove advantageous.

To a lesser extent, hydrogen is mixed with argon or helium for special applications.

2.3.4.1 Argon and helium are colorless, odorless, tasteless and nontoxic gases. Both are

inert gases, which means that they do not readily combine with other elements. They will not

burn nor support combustion. Commercial grades used for welding are 99.99% pure. Argon

is .38% heavier than air and about 10 times heavier than helium. Both gases ionize when

present in an electric arc. This means that the gas atoms lose some of their electrons that

have a negative charge. These unbalanced gas atoms, properly called positive ions, now

have a positive charge and are attracted to the negative pole in the arc. When the arc is

positive and the work is negative, these positive ions impinge upon the work and remove

surface oxides or scale in the weld area.

2.3.4.2 Argon is most commonly used of the shielding gases. Excellent arc starting and

ease of use make it most desirable for manual welding. Argon produces a better cleaning

action when welding aluminum and magnesium with alternating current. The arc produced is


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relatively narrow. Argon is more suitable for welding thinner material. At equal amperage,

helium produces a higher arc voltage than argon. Since welding heat is the product of volts

times amperes, helium produces more available heat at the arc. This makes it more suitable

for welding heavy sections of metal that have high heat conductivity, or for automatic welding

operations where higher welding speeds are required.

2.3.4.3 Argon-helium gas mixtures are used in applications where higher heat input and the

desirable characteristics of argon are required. Argon, being a relatively heavy gas, blankets

the weld area at lower flow rates. Argon is preferred for many applications because it costs

less than helium.

2.3.4.4 Helium, being approximately 10 times lighter than argon, requires flow rates of 2 to

3 times that of argon to satisfactorily shield the arc.

2.3.5 Electrodes - Electrodes for gas tungsten arc welding are available in diameters

from .010" to 1/4" in diameter and standard lengths range from 3" to 24". The most commonly

used sizes, however, are the .040", 1/16", 3/32", and 1/8" diameters.

2.3.5.1 The shape of the tip of the electrode is an important factor in gas tungsten arc

welding. When welding with DCEN, the tip must be ground to a point. The included angle at

which the tip is ground varies with the application, the electrode diameter, and the welding

current. Narrow joints require a relatively small included angle. When welding very thin

material at low currents, a needlelike point ground onto the smallest available electrode may

be necessary to stabilize the arc. Properly ground electrodes will assure easy arc starting,

good arc stability, and proper bead width.

2.3.5.2 When welding with AC, grinding the electrode tip is not necessary. When proper

welding current is used, the electrode will form a hemispherical end. If the proper welding

current is exceeded, the end will become bulbous in shape and possibly melt off to

contaminate the weld metal.

2.3.5.3 The American Welding Society has published Specification AWS A5.12-80 for

tungsten arc welding electrodes that classifies the electrodes on the basis of their chemical

composition, size and finish. Briefly, the types specified are listed below:

1) Pure Tungsten (AWS EWP) Color Code: Green

Used for less critical applications. The cost is low and they give good results at

relatively low currents on a variety of metals. Most stable arc when used on AC, either

balanced wave or continuous high frequency.


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2) 1% Thoriated Tungsten (AWS EWTh-1) Color Code: Yellow

Good current carrying capacity, easy arc starting and provide a stable arc. Less

susceptible to contamination. Designed for DC applications of nonferrous materials.

3) 2% Thoriated Tungsten (AWS EWTh-2) Color Code: Red

Longer life than 1% Thoriated electrodes. Maintain the pointed end longer, used for

light gauge critical welds in aircraft work. Like 1%, designed for DC applications for

nonferrous materials.

4) .5% Thoriated Tungsten (AWS EWTh-3) Color Code: Blue

Sometimes called "striped" electrode because it has 1.0-2.0% Thoria inserted in a

wedge-shaped groove throughout its length. Combines the good properties of pure

and thoriated electrodes. Can be used on either AC or DC applications.

5) Zirconia Tungsten (AWS EWZr) Color Code: Brown

Longer life than pure tungsten. Better performance when welding with AC. Melts more

easily than thoriam-tungsten when forming rounded or tapered tungsten end. Ideal for

applications where tungsten contamination must be minimized.

2.3.6 Summary - Gas Tungsten Arc Welding is one of the major welding processes

today. The quality of the welds produced and the ability to weld very thin metals are the major

features. The weld metal quality is high since no flux is used, eliminating the problem of slag

inclusions in the weld metal. It is used extensively in the aircraft and aerospace industry, where

high quality welds are necessary and also for welding the more expensive metals where the

weld defects become very costly. Metals as thin as .005" can be welded due to the ease of

controlling the current.

2.3.6.1 The major disadvantages of the process are that it is slower than welding with

consumable electrodes and is little used on thicknesses over 1/4" for this reason. Shielding

gas and tungsten electrode costs make the process relatively expensive.

2.4 GAS METAL ARC WELDING

Gas Metal Arc Welding* is an arc welding process that uses the heat of an electric arc

established between a consumable metal electrode and the work to be welded. The electrode

is a bare metal wire that is transferred across the arc and into the molten weld puddle. The

* Gas Metal Arc Welding (GMAW) is the current technology approved by the American Welding Society.Formerly known as "MIG" (Metal Inert Gas) Welding.


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wire, the weld puddle, and the area in the arc zone are protected from the atmosphere by a

gaseous shield. Inert gases, reactive gases, and gas mixtures are used for shielding. The

metal transfer mode is dependent on shielding gas choice and welding current level. Figure 9

is a sketch of the process showing the basic features.

FIGURE 9

WELDING WIRE

WELDING CABLE

SHIELDING GAS

GAS NOZZLE

CONTACT TIP

WORK PIECE

MOLTEN POOL

WELD METAL

ARC

GAS SHIELD

SOLID WIREELECTRODE

TRAVELDIRECTION

GAS METAL ARC WELDING

2.4.0.1 Gas metal arc welding is a versatile process that may be used to weld a wide

variety of metals including carbon steels, low alloy steels, stainless steels, aluminum alloys,

magnesium, copper and copper alloys, and nickel alloys. It can be used to weld sheet metal or

relatively heavy sections. Welds may be made in all positions, and the process may be used

for semiautomatic welding or automatic welding. In semiautomatic welding, the wire feed

speed, voltage, amperage, and gas flow are all preset on the control equipment. The operator

needs merely to guide the welding gun along the joint at a uniform speed and hold a relatively

constant arc length. In automatic welding, the gun is mounted on a travel carriage that moves

along the joint, or the gun may be stationary with the work moving or revolving beneath it.

2.4.0.2 Practically all GMAW is done using DCEP (Electrode positive). This polarity

provides deep penetration, a stable arc and low spatter levels. A small amount of GMAW

welding is done with DCEN and although the melting rate of the electrode is high, the arc is

erratic. Alternating current is not used for gas metal arc welding.

2.4.1 Current Density - To understand why gas metal arc welding can deposit weld

metal at a rapid rate, it is necessary that the term "current density" be understood. Figure 10

shows a 1/4" coated electrode and a 1/16" solid wire drawn to scale. Both are capable of

carrying 400 amperes. Notice that the area of the 1/16" wire is only 1/16 that of the core wire

of the coated electrode. We can say that the current density of the 1/16" wire is 16 times


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greater than the current density

of the 1/4" wire at equal welding

currents. The resultant melt-off

rate of the solid wire is very high.

If we were to increase the current

through the 1/4" coated

electrode to increase the current

density, the resistance heating

through the 14" electrode length would be

excessive, and the rod would become so

hot that the coating would crack, rendering

it useless. The 1/16" wire carries the high

current a distance of less than 3/4", the

approximate distance from the end of the contact tip to the arc.

2.4.2 Metal Transfer Modes

2.4.2.1 Spray transfer is a high current density process that rapidly deposits weld metal in

droplets smaller than the electrode diameter. They are propelled in a straight line from the

center of the electrode. A shielding gas mixture of Argon with 1% to 2% Oxygen is used for

welding mild and low alloy steel, and pure Argon or Argon-Helium mixtures are used for weld-

ing aluminum, magnesium, copper, and nickel alloys. Welding current at which spray transfer

FIGURE 10

AREA = .049 SQ. IN.

AREA = .0031 SQ. IN.CORE WIRE

FLUXCOATING

COATED ELECTRODE

RELATIVE SIZE OF ELECTRODES FOR WELDING AT 400 AMPS

SOLID WIRE

1/4"

1/16"

.049 ÷ .0031 = 16

AA × 16

FIGURE 11

SPRAYTRANSFER

GLOBULARTRANSFER

PULSETRANSFER

MODES OF METAL TRANSFER

1 2 3SHORT CIRCUITING ARC METAL TRANSFER

takes place is relatively high and will vary with the metal being welded, electrode diameter, and

the shielding gas being used. Deposition rates are high and welding is usually limited to the

flat or horizontal fillet position. See Figure 11.


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2.4.2.2 Globular transfer takes place at lower welding currents than spray transfer. There

is a transition current where the transfer changes to globular even when shielding gases using

a high percentage of argon are used. When carbon dioxide (CO2) is used as a shielding gas,the transfer is always globular. In globular transfer, a molten drop larger than the electrode

diameter forms on the end of the electrode, moves to the outer edge of the electrode and falls

into the molten puddle. Occasionally, a large drop will "short circuit" across the arc, causing

the arc to extinguish momentarily, and then instantaneously reignite. As a result, the arc is

somewhat erratic, spatter level is high, and penetration shallow. Globular transfer is not

suitable for out-of-position welding. See Figure 11.

2.4.2.3 Short circuiting transfer is a much used method in gas metal arc welding. It is

produced by using the lowest current-voltage settings and the smaller wires, usually .030",

.035", and .045" diameters. The low heat input makes this process ideal for sheet metal, out-

of-position work, and poor fit-up applications. Often called "short arc welding" because metal

transfer is achieved each time the wire actually short circuits (makes contact) with the weld

puddle. This happens very rapidly. It is feasible for the short circuit frequency to be 20-200

times a second, but in practice, it occurs from 90-100 times a second. Each time the

electrode touches the puddle, the arc is extinguished. It happens so rapidly that it is visible

only on high speed films.

2.4.2.4 Pulse transfer is a mode of metal transfer somewhat between spray and short

circuiting. The specific power source has built into it two output levels: a steady background

level, and a high output (peak) level. The later permits the transfer of metal across the arc.

This peak output is controllable between high and low values up to several hundred cycles per

second. The result of such a peak output produces a spray arc below the typical transition

current.

2.4.2.4.1 Figure 11 shows the transfer method. The arc is initiated by touching the wire to the

work. Upon initial contact, a bit of the wire melts off to form a molten puddle. The wire feeds

forward until it actually contacts the work again, as at 1 in Figure 11, and the arc is

extinguished. The short circuiting current causes the wire to neck down, as shown in 1, until it

melts off, as shown at 2. As soon as the wire is free of the puddle, the arc is reignited and a

molten ball forms at the end of the electrode, as at 3. The wire continues to move forward until

it makes contact with the puddle, and the cycle is repeated.

2.4.2.5 Gas metal arc spot welding is a variation of the process that allows spot welding

of thinner gauge metals, or of a thin gauge metal to a heavier section. The gun is placed

directly against the work and is equipped with a special nozzle to allow escape of the shielding

gas. When the trigger switch is actuated, the following sequence takes place. The shielding


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gas flows for a short interval before wire feeding starts; wire feeding starts; the arc is initiated

and continues for a preset time (usually a few seconds). The welding current and wire feeding

stops, and the shielding gas flows for a short interval before it automatically stops. The

process is also useful for tacking welding pieces in position prior to running the final weld

bead.

2.4.3 EQUIPMENT AND OPERATION - The equipment used for gas metal arc welding

is more complicated than that required for shielded metal arc welding. Initial cost is relatively

high, but the cost is rapidly amortized due to the savings in labor and overhead achieved by

the rapid weld metal deposition.

2.4.3.1 The equipment necessary for gas metal arc welding is listed below:

1) Power source

2) Wire feeder

3) Welding gun

4) Shielding gas supply

5) Solid electrode wire

6) Protective equipment

2.4.3.2 The basic equipment necessary for semiautomatic gas metal arc welding is shown

in Figure 12.

FIGURE 12

FLOWMETERREGULATOR

SHIELDINGGAS

POWERSOURCE

GROUND CABLEWORK

WELDING GUN

WELD CABLE115V CONTACTOR

MAGNETIC

VALVE

TRIGGERCONTROL LEAD

FEED ROLLS

GAS HOSE

WIRE FEEDER

WIRE SPOOL

+ _

SCHEMATIC DIAGRAM SEMI-AUTOMATIC GMAW EQUIPMENT


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LESSON II

2.4.4 Power Source - A direct current, constant voltage power source is recommended

for gas metal arc welding. It may be a transformer-rectifier or a rotary type unit. The lower

open circuit voltage and self-correcting arc length feature, as described in Lesson I, makes it

most suitable. Constant voltage power sources used for spray transfer welding and for flux

cored electrode welding (to be covered later) are the same. However, if the unit is to be used

for short-circuiting arc

welding, it must have

"slope" or slope control.Slope control is a

means of limiting the

high short-circuit current

that is characteristic of

this type welder. Figure

13 shows the effect of

slope on the short-

circuiting current.

2.4.4.1 If we were

short-arc welding at

approximately 150 amperes

and 18 volts, as shown in Figure 13,

and had no slope components in the power source, the current at short-circuit or when the wire

touches the work, would be over 1400 amperes. At this high current, a good length of the wire

would literally explode off the end, cause much spatter, and the arc would be erratic. With the

slope components in the circuit, the short-circuiting current is in the neighborhood of 400

amperes, and the molten ball is sort of pinched off the end of the wire more gently. For those

with an electrical background, it might be added that in some machines, slope is achieved by

adding a reactor in the AC secondary of the power source. In others, a slope resistor is added

in the DC output portion of the circuit. Slope may be adjustable for varying wire diameters or it

may be fixed, giving a good average value for .035" and .045" diameter wires, the two most

popular sizes.

2.4.4.2 Another factor influencing the arc in short-circuiting welding is the rate that the

amperage reaches the short-circuiting current level. Using the example in Figure 13, we know

that the current goes from 150 amperes to 400 amperes during each shorting period. If we

were to plot the current rise on a graph, as in Figure 14, we would see that the current rise if

very rapid, as shown by the broken line.

FIGURE 13

25

20

15

10

5

200 400 600 800 1000 1200 1400

OPERATING POINT

CONSTANT VOLTAGE V/A CURVE

SHORT CIRCUITINGCURRENT NO SLOPE

SHORT CIRCUITING CURRENTWITH SLOPE

EFFECT OF SLOPE ON SHORT CIRCUITING CURRENT

VOLTS


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This rapid current rise can be

by using a device called an

(sometimes called a stabilizer)

output circuit of the welder. An

merely an iron core wound

turns of heavy wire. It does

current flow, but it acts

somewhat like a fly wheel or

damper by retarding the rate of

rise as shown by the solid

line. By preventing the

rapid current rise, the arc

becomes smoother,

spatter is reduced, and

bead shape and

appearance are

improved. Because the inductor influences the time function, its design determines arc on-off

time, and short-circuit frequency. Some power sources have a selector that can switch in

several different inductance values to finely tune the arc.

2.4.4.4 Welding power sources designed for gas metal arc welding have a 115 volt outlet to

provide power to operate the wire feeder. They also have a receptacle to receive the electrical

power required to close the main contactor in the power source, which turns on the welding

power to the welding gun when the gun trigger is actuated.

2.4.4.5 Additional advancements in equipment technology have introduced many new

models. Inverters, as well as microprocessor controls, have created the greatest attention. In

addition, multipurpose machines have provided the user with greater flexibility with a variety of

capabilities.

2.4.4.6 Global competition will continue to have a profound influence on future

advancements in arc welding equipment. As energy prices rise, greater demands for more

efficient equipment will follow.

2.4.5 Wire Feeder - When welding with a constant voltage power source, as is the case

in most gas metal arc welding applications, the prime function of the wire feeder is to deliver

the welding wire to the arc at a very constant speed. Since the wire feed speed determines

the amperage, and the amperage determines the amount of heat at the arc, inconsistent wire

feed speed will produce welds of varying penetration and bead width. Advanced electronics

FIGURE 14

TIME - MILLISECONDSEFFECT OF INDUCTANCE ON CURRENT RISE

400 AMPSWITHOUT INDUCTANCE

WITH INDUCTANCE

150 AMPS


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technology makes it possible to design motor speed controls that will produce the same

speed, even though the load on the motor varies or the input voltage to the motor may fluctuate.

2.4.5.1 A limited amount of gas metal arc welding is performed with constant current type

power sources. In this case, the motor speed automatically varies to increase or decrease the

wire feed speed as the arc length varies to maintain a constant voltage.

2.4.5.2 The wire feeder also controls the main contactor in the power source for safety

reasons. This assures that the welding wire will only be energized when the switch on the

welding gun is depressed.

2.4.5.3 The flow of shielding gas is controlled by a solenoid valve (magnetic valve) in the

wire feeder to turn the shielding gas on and off when the gun switch is actuated. Most feeders

utilize a dynamic breaking circuit to quickly stop the motor at the end of a weld to prevent a

long length of wire protruding from the gun when the weld is terminated. Most feeders have a

burn-back circuit that allows the welding current to stay on for a short period of time after wire

feeding has stopped, to allow the wire to burn back exactly the right amount for the next arc

initiation.

2.4.5.4 The feed rolls, sometimes called drive rolls, pull the wire off the spool or reel, and

push it through a feed cable or conduit to the welding gun. These rolls must usually be

changed to accommodate each different wire diameter, although some rolls are designed to

feed a combination of sizes.

2.4.6 Welding Gun - The function of the welding gun, sometimes referred to as a torch, is

to deliver the welding wire, welding current, and shielding gas to the welding arc. Guns are

available for semi-automatic operation and for automatic operation, where they are fixed in the

automatic welding head.

2.4.6.1 Guns for GMAW have several characteristics in common. All have a copper alloy

shielding gas nozzle, that delivers the gas to the arc area in a nonturbulent, angular pattern to

prevent aspiration of air. The nozzle may be water cooled for semiautomatic welding at high

amperage and for automatic welding where the arc time is of long duration. Welding current is

transferred to the welding wire as the wire travels through the contact tip or contact tube

located inside the gas nozzle (Refer to Figure 9). The hole in the contact tip through which the

wire passes is only a few thousandths of an inch larger than the wire diameter. A worn contact

tip will result in an erratic arc due to poor current transfer. Figure 15 shows a few different

semiautomatic gun configurations that are commonly used for GMAW.


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2.4.6.2 The curved neck or "goose neck" type is probably the most commonly used. It

allows the best access to a variety of weld joints. The wire is pushed to this type of gun by the

feed rolls in the wire feeder through a feed cable or conduit that usually is 10 or 12 feet in

length. The shielding gas hose, welding current cable, and trigger switch leads are supplied

with the welding gun.

2.4.6.3 The pistol type gun is similar to the curved neck type, but is less adaptable for

difficult to reach joints. The pistol type is also a "push" type gun and is more suitable for gas

metal arc spot welding applications.

2.4.6.4 The self contained type has an electric motor in the handle and feed rolls that pull the

wire from a 1 or 2 pound spool mounted on the gun. The need for a long wire feed cable is

eliminated, and wire feed speed may be controlled by the gun. Guns of this type are often

used for aluminum wire up to .045" diameter, although they may also be used for feeding steel

or other hard wires.

2.4.6.5 The pull type gun has either an electric motor or an air motor mounted in the handle

that is coupled to a feeding mechanism in the gun. The spool of wire is located in the control

cabinet that may be located as far as fifty feet from the gun. When feeding such long

distances, a set of "push" rolls located in the control cabinet assist in feeding the wire. This

then becomes known as a push-pull feed system and is especially useful in feeding the softer

wires such as aluminum.

2.4.7 SHIELDING GASES - In gas metal arc welding, there are a variety of shielding

gases that can be used, either alone or in combinations of varying degrees. The choice is

dependent on the type of metal transfer employed, the type and thickness of metal, the bead

CURVED NECK PISTOL TYPE

SELF CONTAINEDPULL TYPE

SEMI-AUTOMATIC GMAW GUN TYPES

FIGURE 15


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profile (See Figure 16), penetration, and speed of welding. In our discussion, we will deal with

the more common choices used for the various transfer processes.

2.4.7.1 Short Circuiting Transfer - Straight carbon dioxide (CO2) is often used for short

circuiting arc welding because of its low cost. The deep penetration usually associated with

CO2 is minimized because of the low amperage and voltage settings used with this process.

Compared to other gas mixes, CO2 will produce a harsher arc and therefore, greater spatter

levels. Usually, this is minimized by maintaining a short arc length and by careful adjustment of

the power supply inductance. The temperatures reached in welding will cause carbon dioxide

to decompose into carbon monoxide and oxygen. To reduce the possibility of porosity caused

by entrapped oxygen in the weld metal, it is wise to use electrodes that contain deoxidizing

elements, such as silicon and manganese. If the current is increased above the short circuiting

range, the use of carbon dioxide tends to produce a globular transfer.

2.4.7.1.1 Mixing argon in proportions of 50-75% with carbon dioxide will produce a smoother

arc and reduce spatter levels. It will also widen the bead profile, reduce penetration, and

encourage "wetting". Wetting, i.e., a uniform fusion, along with joining edges of the base metal

and the weld metal, minimizes the weld imperfection known as undercutting (See Figure 17).

FERROUS METALS NON-FERROUS METALS

CO2 ARGON + CO2 ARGON + O2 ARGON HELIUM

BEAD PROFILE

FIGURE 16

FIGURE 17

UNDERCUT WETTING

2.4.7.1.2 The 75% Argon/25 CO2 mixture is often chosen for short circuit welding of thin

sections, whereas the 50-50 combination works well on thicker sections.

2.4.7.1.3 It should be noted that shielding gases can affect the metallurgy of the weld metal.

As an example, a combination of argon and carbon dioxide may be used for welding stainless

steel, but as the carbon dioxide breaks down, excessive carbon may be transferred into the


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weld metal. Corrosion resistance in stainless steel is reduced as the carbon content

increases. To counteract this possibility, a less reactive mixture of 90% helium - 7-1/2% argon

- 2-1/2% CO2 is sometimes chosen. This combination, known as a trimix, provides good arcstability and wetting.

2.4.7.2 Spray Arc Transfer - Pure argon produces a deep constricted penetration at the

center of the bead with much shallower penetration at the edges (Figure 16). Argon performs

well on nonferrous metals, but when used on ferrous metals, the transfer is somewhat erratic

with the tendency for the weld metal to move away from the center line. To make argon suit-

able for spray transfer on ferrous metals, small additions of 1 to 5% oxygen have proven to

provide remarkable improvements. The arc stabilizes, becomes less spattery, and the weld

metal wets out nicely. If the percentage of argon falls below 80%, it is impossible to achieve

true spray transfer.

2.4.7.2.1 Pure helium or combinations of helium and argon are used for welding nonferrous

metals. The bead profile will broaden as the concentration of helium increases.

2.4.7.3 Pulse Spray Transfer - The selection of shielding gas must be adequate enough to

support a spray transfer. Material type, thickness, and welding position are essential variables

in selecting a particular shielding gas. The following is a list of recommended gases:

Carbon Steel Argon/CO2/O2/He (He less than 50%)

Alloy Steel Argon/CO2/O2/He (He less than 50%)

Stainless Argon/O2/CO2 (CO2 max. 2%)

Copper, Nickel, & Cu-Ni Alloys Argon/Helium

Aluminum Argon/Helium

2.4.8 Electrodes - The solid electrodes used in GMAW are of high purity when they come

from the mill. Their chemistry must be closely controlled and some types purposely contain

high levels of deoxidizers for use with CO2 shielding.

2.4.8.1 The electrode manufacturer draws down the electrode to a finished diameter that,

with GMAW, is usually quite small. Diameters from .030" thru 1/16" are common.

2.4.8.2 Most steel GMAW electrodes are copper plated as a means of protecting the

surface. The copper inhibits rusting, provides smooth feeding, and helps electrical

conductivity.

2.4.8.3 Information on types and classifications will be covered in a future lesson.


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© COPYRIGHT 1998 THE ESAB GROUP, IN

LESSON II

2.5 FLUX CORED ARC WELDING

Flux Cored Arc Welding (FCAW) is quite similar to GMAW as far as operation and

equipment are concerned. The major difference is that FCAW utilizes an electrode that is very

different from the solid electrode used in GMAW. The flux cored electrode is a fabricated

electrode and as the name implies, flux material is deposited into its core. The flux cored

electrode begins as a flat metal strip that is formed first into a "U" shape. Flux and alloying

elements are deposited into the "U" and then the shape is closed into a tubular configuration

by a series of forming rolls.

2.5.0.1 The flux cored electrode is a continuous electrode that is fed into the arc where it is

melted and transferred into the molten puddle. As in GMAW, the flux cored process depends

on a gas shield to protect the weld zone from detrimental atmospheric contamination. With

FCAW, there are two primary ways this is accomplished (See Figure 18). The gas is either

applied externally, in which case the electrode is referred to as a gas shielded flux cored

electrode, or it is generated from the decomposition of gas forming ingredients contained in

the electrode's core. In this instance, the electrode is known as a self-shielding flux cored

electrode. In addition to the gas shield, the flux cored electrode produces a slag covering for

further protection of the weld metal as it cools. The slag is manually removed with a wire brush

or chipping hammer.

2.5.1 Self Shielded Process - The main advantage of the self shielding method is that

its operation is somewhat simplified because of the absence of external shielding equipment.

FIGURE 18

GAS CUP

GAS SHIELD

FLUX CORE

GAS SHIELDED

CONTACT TIP

INSULATEDGUIDE TUBE

SELF SHIELDED

CONTACT TIP

FLUX CORE

FLUX-CORED ARC WELDING


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Although self shielding electrodes have been developed for welding low alloy and stainless

steels, they are most widely used on mild steels. The self shielding method generally uses a

long electrical stick-out (distance between the contact tube and the end of the unmelted elec-

trode) commonly from one to four inches. Electrical resistance is increased with the long

extension, preheating the electrode before it is fed into the arc. This enables the electrode to

burn off at a faster rate and increases deposition. The preheating also decreases the heat

available for melting the base metal, resulting in a more shallow penetration than the gas

shielded process.

2.5.1.1 A major drawback of the self shielded process is the metallurgical quality of the

deposited weld metal. In addition to gaining its shielding ability from gas forming ingredients

in the core, the self shielded electrode contains a high level of deoxidizing and denitrifying

alloys, primarily aluminum, in its core. Although the aluminum performs well in neutralizing the

affects of oxygen and nitrogen in the arc zone, its presence in the weld metal will reduce

ductility and impact strength at low temperatures. For this reason, the self shielding method is

usually restricted to less critical applications.

2.5.1.2 The self shielding electrodes are more suitable for welding in drafty locations than

the gas shielded types. Since the molten filler metal is on the outside of the flux, the gases

formed by the decomposing flux are not totally relied upon to shield the arc from the

atmosphere. The deoxidizing and denitrifying elements in the flux further help to neutralize the

affects of nitrogen and oxygen present in the weld zone.

2.5.2 The Gas Shielded Process - A major advantage with the shielded flux cored

electrode is the protective envelope formed by the auxiliary gas shield around the molten

puddle. This envelope effectively excludes the natural gases in the atmosphere without the

need for core ingredients such as aluminum. Because of this more thorough shielding, the

weld metallurgy is cleaner which makes this process suitable for welding not only mild steels,

but also low alloy steels in a wide range of strength and impact levels.

2.5.2.1 The gas shielded method uses a shorter electrical stickout than the self shielded

process. Extensions from 1/2" to 3/4" are common on all diameters, and 3/4" to 1-1/2" on

larger diameters. Higher welding currents are also used with this process, enabling high

deposition rates to be reached. The auxiliary shielding helps to reduce the arc energy into a

columnar pattern. The combination of high currents and the action of the shielding gas

contributes to the deep penetration inherent with this process. Both spray and globular

transfer are utilized with the gas shielded process.


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2.5.3 Current Density - Flux cored arc welding utilizes the same principles of current

density, as explained in section 2.4.1, but there is one significant difference between the flux

cored electrode and the solid electrode. With the flux cored electrode, the granular core

ingredients are poor electrical conductors and therefore, the current is carried primarily

through the outer metal sheathing. When an equal diam-

eter cross section of the two are compared (See Figure

19), it is seen that the flux cored electrode has

a smaller current carrying area than the solid

electrode. This greater concentration of

current in a smaller area increases the

burnoff rate.

2.5.3.1 When all other factors are equal,

the deposition rate of the flux cored

electrode is somewhat higher than the

solid electrode.

2.5.4 EQUIPMENT - The equipment used for flux cored arc welding is the same as

shown previously in Section 2.3.2.2, Figure 12, with the exception that the self shielded

method does not need the external gas apparatus.

2.5.4.1 Flux cored arc welding is done with direct current. All of the gas shielded electrodes

are designed for DCEP operation. The self shielded electrodes are either designed

specifically for DCEN or DCEP.

2.5.5 Power Source - The recommended power source is the direct current constant

voltage type. The constant current type can be used but with less satisfactory results.

2.5.6 Wire Feeder - The function of the wire feeder in FCAW is the same as discussed in

the section on GMAW. Since the flux cored electrode is tubular in construction, precautions

must be taken not to flatten the electrode. To facilitate feeding by means other than pressure

alone, specially designed feed rolls with knurled or grooved surfaces are used. Some feeders

use four feed rolls rather than two to minimize unit pressure on the electrode.

2.5.7 The Welding Gun - As compared to GMAW, the main difference in FCAW welding

guns is in those used with the self shielding process. The gun is somewhat more compact due

to the absence of an external gas shielding nozzle. Since the self shielding process normally

requires a longer electrode extension, the self shielding gun may have an insulated guide tube

(Refer back to Figure 18) to give stability to the electrode. Water cooled guns are available for

high duty semi-automatic welding and for automatic welding.

FIGURE 19

CURRENT PATH

1/16" FLUX-COREDELECTRODE 1/16" SOLID

ELECTRODE


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2.5.7.1 Flux cored welding generates fumes, that for environmental reasons, must be

removed from the welding area. This is usually done with an external exhaust system, but

welding guns with internal fume extractors have been developed. They are heavier than the

regular gun and must be properly maintained so that the extracting mechanism does not

disturb the shielding gas.

2.5.8 SHIELDING GASES - Carbon dioxide is the most widely used gas for auxiliary

shielding of the flux cored electrode. The other commonly used gas is a mixture of 75% Argon

and 25% CO2.

2.5.8.1 A carbon dioxide shield produces deep penetration and the transfer is globular. As

previously discussed, CO2 will dissociate in the heat of the arc. To counteract thischaracteristic, deoxidizing elements are added to the core ingredients of the electrode. The

deoxidizers react to form solid oxide compounds that float to the surface as part of the slag

covering.

2.5.8.2 The addition of Argon to CO2 will increase the wetting action, produce a smooth arcarc, and reduce spatter. The transfer is spray-like, and the penetration is somewhat less than

with the straight carbon dioxide.

2.5.8.3 While some flux cored electrodes are designed to operate well on both the 100%

CO2 or the 75/25 mixture, others are formulated specifically for the CO2 shield or the Argon/

CO2 mixture. If the recommended gas is not used with these electrodes, the weld chemistrymay be affected. The reason for this is that inert gas, such as Argon, does not react with the

other elements; therefore, allowing them to be transferred across the arc into the weld metal.

An electrode designed for CO2 shielding contains deoxidizing elements, such as silicon andmanganese. If a high percentage of Argon is used in the shielding medium, a large portion of

these elements may pass into the weld metal causing the weld metallurgy to be less ductile

than intended.

2.5.8.3 The opposite happens with electrodes formulated for a 75/25 mixture. These

electrodes are usually designed for high yield and tensile strength. If a high percentage of CO2

is used with them, the CO2 may react with the elements needed to attain these strength levels,thereby preventing them from passing into the weld metal.

2.6 SUBMERGED ARC WELDING

Submerged Arc Welding (SAW) is different from the previously explained arc welding

processes in that the arc is not visible. The arc is submerged beneath loose granular flux. A

continuous electrode is fed by automatic drive rolls through an electrode holder where current


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is picked up at the contact tube. The electrode moves into the loose flux and the arc is

initiated. The flux is deposited from a separate container that moves at the same pace as the

electrode assuring complete coverage (See Figure 20).

2.6.1 Submerged Arc Flux - The flux helps form the molten puddle, slows the cooling

rate, and acts as a protective shield. The flux, which is in close contact with the arc, is fused

into a slag cover and that which is not fused is collected for reuse. The flux can contain alloying

elements that, when molten, will pass into the weld metal affecting the metallurgy. Some fluxes

are specifically prepared for their alloy altering capabilities while others, known as neutral

fluxes, are chosen when a minimal alloy change is desired. Although these latter fluxes are

called "neutral", they still have the ability to slightly alter the weld chemistry.

FIGURE 20

FLUX HOPPER

LOOSE GRANULAR FLUX

MOLTEN PUDDLE

FUSED SLAG COVERSOLIDIFIED WELD METAL

BASEMETAL

ELECTRODE

SUBMERGED ARC WELDING

2.6.2 The Welding Gun - Although there are hand-held welding guns for the submerged

arc process, the majority of SAW is done with fully automatic equipment. The basic compo-

nents include a wire feeder, a power source, a flux delivery system, and in some instances, an

automatic flux recovery system.

2.6.3 Power Sources - The power source can be a constant current AC transformer, or it

may be a DC rectifier or generator of either the constant current or constant voltage variety.

The power source must be rated for high current output. When current requirements exceed

the value of a single machine, two or more of the same type may be connected in parallel.

2.6.4 Equipment - Most submerged arc welding is done with DCEP because it provides

easy arc starting, deep penetration and excellent bead shape. DCEN provides the highest


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deposition rates but minimum penetration. Alternating current is often used as a trailing arc in

tandem arc applications. In this type of application, the leading DCEP arc provides deep

penetration, and the closely trailing AC arc provides high deposition with a minimum of arc

blow.

2.6.5 Electrodes - A variety of ferrous and nonferrous electrodes are used in submerged

arc welding. They are usually solid electrodes refined with the appropriate alloys at the steel

mill, and then shipped to electrode manufacturers where they are drawn down to a specific

diameter and packaged. There is another type of sub arc electrode known as a composite

electrode, that is fabricated in the same manner as a flux cored electrode. A chief advantage

of this type is that the alloying elements can be added to the core of the electrode more

cheaply than a steel mill can produce those same alloys in a solid form. The electrodes for

SAW vary in diameter from 1/16 inch to 1/4 inch with the larger diameters being the most

widely used.

2.6.6 Summary - Submerged arc welding has some advantages over other welding

processes. Since the radiance of the arc is blanketed by the loose flux, there is no need for a

protective welding hood (although safety glasses are recommended), there is no spatter and

only a very minimal amount of fumes escape from under the blanket. High welding currents,

quite commonly in the 300 to 1600 ampere range, are used. These high currents, combined

with fast travel speeds, make SAW a high deposition process that is especially suitable for

applications that require a series of repetitious welds. Some setups allow two or more elec-

trodes to be fed simultaneously into the joint, further increasing the deposition rate and speed.

2.6.6.1 Although SAW has these advantages, it does have some limitations. The flux must

be deposited and collected for every welding pass. This requires additional equipment and

handling. Also because of the loose flux, the process is limited to the flat and horizontal

positions. The equipment for SAW is commonly quite bulky which limits its mobility, and

although the process works well on thick materials, it usually is not satisfactory for thin gauge

material. The process requires care in the operation. The amperages commonly used may

cause excessive heat buildup in the base metal, that may result in distortion or brittleness.


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2.7 ELECTROSLAG AND ELECTROGAS WELDING

Electroslag Welding (ESW) and Electrogas Welding (EGW) comprise only a minor portion

of all welding done in the country, but they are uniquely adapted to certain applications,

primarily the joining of very thick materials. The joining of a 12 inch material along a 40 foot

line is not an uncommon application for the Electroslag process.

2.7.1 Electroslag Welding (See Figure 21) is technically not an arc welding process,

although it utilizes a current carrying consumable electrode. The only time there is an arc

between the electrode and the work piece is when current is initially charged through the

electrode. This initial charge heats a layer of loose flux that becomes molten and extinguishes

the arc.

2.7.2 Flux - The flux used in ESW is high in electrical resistance. As current is applied,

enough heat is generated from this resistance to keep the flux, base metal, and electrode in a

molten state. This axis of the weld joint is on a vertical plane. The two pieces of metal, usually

of the same thickness, are positioned so that there is an opening between them. One or more

electrodes are fed into the opening through a welding bead that travels vertically as the joint is

filled. To contain the molten puddle, water cooled copper shoes or dams are placed on the

sides of the vertical cavity. As the weld joint solidifies, the dams move vertically so as to

always remain in contact with the molten puddle.

2.7.3 Process - A variation of ESW is the consumable guide method. The process is the

same with this method except that the guide tube that feeds the electrode to the molten pool is

WATER INLET/OUTLET

COPPER SHOE

BASE METAL

SOLIDIFIED METALWELD POOL

MOLTEN FLUX

GUIDE TUBE(CONSUMABLE GUIDE METHOD)

ELECTRODE

ELECTROSLAG WELDING

FIGURE 21


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LESSON II

also consumed. The chief advantage with this method is the elimination of the electrode

holder which must move vertically with the weld pool. Also since the guide tube is consumed,

the deposition rate is slightly increased with this method.

2.7.4 Equipment - The equipment used in ESW is all automatic and of special design.

The power source may use either AC or DC current. The electrode may be either solid or flux

cored, although if the flux cored is used, it must be specially formulated so as not to contain its

normal amount of slag forming ingredients.

2.7.5 Summary - Electrogas Welding is similar to ESW as far as the mechanical as-

pects are concerned. The equipment is automatic, the welding head travels vertically, and the

molten puddle is retained by shoes on the sides of the joint. The difference is that Electrogas

Welding utilizes an arc and it is externally gas shielded. The power source is also limited to

DC operation. The electrodes used in EGW can be either solid or flux cored.


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LESSON II

APPENDIX A

LESSON II - GLOSSARY OF TERMS

Arc Blow - Deviation of the direction of the welding arc caused by magnetic fields in the

work piece when welding with direct current.

Straight

Polarity- Welding condition when the electrode is connected to the negative terminal

and the work is connected to the positive terminal of the welding power source.

ReversePolarity

- Welding condition when the electrode is connected to the positive terminal

and the work is connected to the negative terminal of the welding power

source.

Slag - The brittle mass that forms over the weld bead on welds made with coated

electrodes, flux cored electrodes, submerged arc welding and other slag

producing welding processes. Welds made with the gas metal arc and the

gas tungsten arc welding processes are slag free.

Manual ArcWelding

- Welding with a coated electrode where the operator's hand controls travel

speed and the rate the electrode is fed into the arc.

Semi-Automatic

Welding- Welding with a continuous solid wire or flux cored electrode where the wire

feed speed, shielding gas flow rate, and voltage are preset on the equipment,

and the operator guides the hand held welding gun along the joint to be

welded.

SlagInclusion

- A weld defect where slag is entrapped in the weld metal before it can float to

the surface.

Root Pass - The initial pass in a multi-pass weld, usually requiring 100% penetration.


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Gas Ions - Shielding gas atoms that, in the presence of an electrical current, lose one or

more electrons and therefore, carry a positive electrical charge. The provide

a more electrically conductive path for the arc between the electrode and the

work piece.

HighFrequency - (as applied to gas-tungsten arc welding)

An alternating current consisting of over 50,000 cycles per second at high

voltage, low amperage that is superimposed on the welding circuit in GTAW

power sources. It ionizes a path for non-touch arc starting and stabilizes the

arc when welding with alternating current.

Inert Gases - Gases that are chemically inactive. They do not readily combine with other

elements.

Flux - In arc welding, fluxes are formulations that, when subjected to the arc, act as

a cleaning agent by dissolving oxides, releasing trapped gases and slag and

generally cleaning the weld metal by floating the impurities to the surface

where they solidify in the slag covering. The flux also serves to reduce spatter

and contributes to weld bead shape. The flux may be the coating on the

electrode, inside the electrode as in flux cored types, or in a granular form as

used in submerged arc welding.

Current

Density - The amperes per square inch of cross-sectional area of an electrode. High

current density results in high electrode melt-off rate and a concentrated, deep

penetrating arc.

Slope or SlopeControl - A necessary feature in welding power sources used for short circuiting arc

welding. Slope Control reduces the short circuiting current each time the

electrode touches the weld puddle (See Section 2.5.3).

Inductance - (as applies to short circuiting arc welding)

A feature in welding power sources designed for short circuiting arc welding

to retard the rate of current rise each time the electrode touches the weld

puddle.


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Contact Tip - That part of a gas metal arc welding gun or flux cored arc welding gun that

transfers the welding current to the welding wire immediately before the wire

enters the arc.

Spray

Transfer

- Mode of metal transfer across the arc where the molten metal droplets are

smaller than the electrode diameter and are axially directed to the weld puddle.

Requires high voltage and amperage settings and a shielding gas of at least

80% argon.

Globular

Transfer

- Mode of metal transfer across the arc where a molten ball larger than the

electrode diameter forms at the tip of the electrode. On detachment, it takes

on an irregular shape and tumbles towards the weld puddle sometimes

shorting between the electrode and work at irregular intervals. Occurs when

using shielding gases other than those consisting of at least 80% argon and

at medium current settings.

Pulse

Transfer

- Mode of metal transfer somewhat between spray and short circuiting. The

specific power source has built into it two output levels: a steady background

level, and a high output (peak) level. The later permits the transfer of metal

across the arc. This peak output is controllable between high and low values

up to several hundred cycles per second. The result of such a peak output

produces a spray arc below the typical transition current.

Short- circuiting

Transfer

- Mode of metal transfer in gas metal arc welding at low voltage and amperage.

Transfer takes place each time the electrode touches or short-circuits to the

weld puddle, extinguishing the arc. The short-circuiting current causes the

electrode to neck down, melt off, and then repeats the cycle.

Trimix or

Triple Mix

- A shielding gas consisting of approximately 90% helium, 7-1/2% argon, and

2-1/2% carbon dioxide used primarily for short-circuiting arc welding of

stainless steels. Maintains corrosion resistance of the stainless steel and

produces good wetting and excellent weld bead shape.


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LESSON II

ElectricalStick-Out

- In any welding process using a solid or flux cored wire, the electrical stick-out

is the distance from the contact tip to the unmelted electrode end. Sometimes

called the "amount of wire in resistance". This distance influences melt-off

rate, penetration, and weld bead shape.

Out-of-PositionWelds

- Welds made in positions other than flat or horizontal fillets.

Weld

Positions

-

FLAT HORIZONTAL FILLET

VERTICAL OVERHEAD

HORIZONTALBUTT

POSITIONED FILLET(FLAT)


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BASICWELDING FILLER

METAL TECHNOLOGY


LESSON IIICOVERED ELECTRODES FOR

WELDING MILD STEELS

An Introduction to Mild SteelCovered Electrodes




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TABLE OF CONTENTSLESSON III

COVERED ELECTRODES FOR WELDINGMILD STEELS

3.1 DEVELOPMENT OF COVERED ELECTRODES............................. 1

3.2 MANUFACTURING COVERED EELCTRODES .............................. 1

3.2.1 Functions of Electrode Coatings ....................................................... 3

3.2.2 Classification of Coating Ingredients ................................................ 4

3.3 AWS SPECIFICATION A5.1-91 ........................................................ 6

3.3.1 Chemical Composition of Weld Metal ............................................... 7

3.3.2 Mechanical Properties (AWS A5.1-91) ............................................. 7

3.3.3 Individual Electrode Characteristics .................................................. 8

3.4 SELECTING THE PROPER MILD STEEL ELECTRODE ................ 11

3.4.1 Typical Electrode Use by Welding Classification .............................. 12

3.4.2 Electrode Deposition......................................................................... 14

3.5 ACID AND BASIC SLAG SYSTEMS ................................................ 15

3.6 ADVANTAGES AND DISADVANTAGES OF MILD STEEL

COVERED ELECTRODES............................................................... 15

3.7 ESAB SUREWELD MILD STEEL COVERED ELECTRODES

FEATURES & DATA.......................................................................... 16

3.7.1 SUREWELD 10P (AWS E6010) ....................................................... 16

3.7.2 SUREWELD 710P (AWS E7010-P1) ............................................... 17

3.7.3 SUREWELD 810P (AWS E8010-P1) ............................................... 18

3.7.4 SUREWELD SW14 (AWS E6011).................................................... 19

3.7.5 SUREWELD SW612 (AWS E6012) ................................................. 20

3.7.6 SUREWELD SW15 (AWS E6013) .................................................... 21


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3.7.7 6013LV (AWS E6013) ....................................................................... 21

3.7.8 SUREWELD SW15-IP (AWS E7014) ................................................ 22

3.7.9 SUREWELD 70LA-2 (AWS E7016) ................................................. 23

3.7.10 ATOM ARC 7018 (AWS E7018) ........................................................ 24

3.7.11 ATOM ARC 7018AC (AWS E7018)................................................... 25

3.7.12 SUREWELD 7024 (AWS E7024) Conforms to 7024-1 ..................... 26

Appendix A GLOSSARY OF TERMS................................................................... 27

TABLE OF CONTENTSLESSON III - Con't


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LESSON III

3.1 Development of Covered ElectrodesDuring the 1890's, arc welding was accomplished with bare metal electrodes. The welds produced were porous and brittle because the molten weld puddle absorbed larg quantities of oxygen and nitrogen from the atmosphere. Operators noticed that a rusty rod produced a better weld than a shiny clean rod. Observations also showed than an improved weld could be made by wrapping the rod in newspaper or bywelding adjacent to a pine board placed close to and parallel with the weld being made. In these cases, some degree of shielding the arc form the atmosphere was being accomplished. These early observationsled to the development of the coated electrode. 3.1.0.1 Around 1920, the A.O. Smith Corporation developed an electrode spirally wrapped with paper, soaked in sodium silicate, and then baked. This was the first of the cellulosic type electrodes. It produced an effective gas shield in the area and greatly improved the ductility of the weld metal. 3.1.0.2 Because of the method used to manufacture these paper covered electrodes, it was difficult to effectively add other ingredients to the coating. In 1924, the A.O. Smith Corporation began work on coatings that could be extruded over the core wire. This method allowed the addition of other flux ingredients to furhter improve or modify the weld metal and by 1927, these electrodes were being produced commercially. 3.1.0.3 Since 1927, many improvements have been made and many different types of electrodes have been developed and produced. Through variations in the formulations of the covering and the amount of covering on the mild steel core wire, many different classifications of electrodes are produced today. 3.2 Manufacturing Covered Electrodes Mild steel covered electrodes, also commonly called coated electrodes, consist of only two major elements;the core wire or rod and the flux covering. The core wire is usually low carbon steel. It must contain only small amounts of aluminum and copper, and the sulfur and phosphorous levels must be kept very low since they can cause undesirable brittleness in the weld metal. The raw material for the core wire is hot-rolled rod (commonly called "hot rod"). It is


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LESSON III

received in large coils, cleaned, drawn down to the proper electrode diameter, straightened,

and cut to the proper electrode length.

3.2.0.1 The coating ingredients, from which there are literally hundreds to choose, are

carefully weighed, blended in a dry state, wet mixed, and compacted into a large cylinder that

fits into the extrusion press. The coating is extruded over the cut core wires which are fed

through the extrusion press at a rapid rate. The coating material is removed from the end of

the electrode that is clamped into the electrode holder to assure electrical contact, and also

from the welding end of the electrode to assure easy arc initiation.

3.2.0.2 The electrodes are then stamped with the type number for easy identification before

entering the ovens, where they go through a controlled bake cycle to insure the proper mois-

ture content before packaging.

3.2.0.3 Of the many quality control checks made during the manufacturing process, one of

the most important is the procedure that insures that the coating thickness is uniform. In

shielded metal arc welding, the coating crater, or the cup-like formation of the coating, that

extends beyond the melting core wire, performs the function of concentrating and directing the

arc. See Figure 1.

3.2.0.4 Concentration and direction of the arc stream is attained by having a coating crater,

somewhat similar to the nozzle on a water hoze, directing the flow of weld metal. When the

coating is not concentric to the core wire, it can cause the condition shown at B in Figure 1.

The poor arc direction causes inconsistent weld beads, poor shielding, and lack of penetra-

tion. The electrode burns off unevenly, leaving a projection on the side where the coating is the

heaviest. This condition is often referred to as "fingernailing."

A B

CONCENTRIC COATING

GOOD ARC DIRECTION

CONCENTRATED ARC

NON-CONCENTRIC COATING

POOR ARC DIRECTION

EFFECT OF COATING CONCENTRICITY

FIGURE 1


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LESSON III

3.2.1 Functions of Electrode Coatings - The ingredients that are commonly used in

coatings can be classified physically in a broad manner as liquids and solids. The liquids are

generally sodium silicate or potassium silicate. The solids are powdered or granulated mate-

rials that may be found free in nature, and need only concentration and grinding to the proper

particle size. Other solid materials used are produced as a result of chemical reactions, such

as alloys or other complex synthetic compounds.

3.2.1.1 The particle size of the solid material is an important factor. Particle size may be as

coarse as fine sand, or as minute as sub-sieve size.

3.2.1.2 The physical structure of the coating ingredients may be classified as crystalline,

fibrous or amorphous (non-crystalline). Crystalline materials such as rutile, quartz and mica

are commonly used. Rutile is the naturally occurring form of the mineral titanium dioxide and

is widely used in electrode coatings. Fibrous materials such as wood fibers, and non-crystal-

line materials such as glasses and other organic compounds are also common coating ingre-

dients.

3.2.1.3 The functions of the coating on covered electrodes are as follows:

a) Shielding of the Weld Metal - The most important function of a coating is to

shield the weld metal from the oxygen and nitrogen of the air as it is being transferred across

the arc, and while it is in the molten state. This shielding is necessary to ensure the weld metal

will be sound, free of gas pockets, and have the right strength and ductility. At the high tem-

peratures of the arc, nitrogen and oxygen combine readily with iron to form iron nitrides and

iron oxides that, if present in the weld metal above certain minimum amounts, will cause brittle-

ness and porosity. Nitrogen is the primary concern since it is difficult to control its effect once it

has entered the deposit. Oxygen can be counteracted by the use of suitable deoxidizers. In

order to avoid contamination from the air, the stream of molten metal must be protected or

shielded by gases that exclude the surrounding atmosphere from the arc and the molten weld

metal. This is accomplished by using gas-forming materials in the coating that break down

during the welding operation and produce the gaseous shield.

b) Stabilization of the Arc - A stabilized arc is one that starts easily, burns

smoothly even at low amperages, and can be maintained using either a long or a short arc

length.

c) Alloying Additions to Weld Metal - A variety of elements such as chromium,

nickel, molybdenum, vanadium and copper can be added to the weld metal by including them

in the coating composition. It is often necessary to add alloys to the coating to balance the

expected loss of alloys of the core wire during the welding operation, due to volatization and


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LESSON III

chemical reaction. Mild steel electrodes require small amounts of carbon, manganese and

silicon in the deposit to give sound welds of the desired strength level. A portion of the carbon

and manganese is derived from the core wire, but it is necessary to supplement it with

ferromanganese and in some cases ferrosilicon additions in the coating.

d) Concentration of the Arc Stream - Concentration or direction of the arc

stream is attained by having a coating crater form at the tip of the electrodes as discussed

earlier. Use of the proper binders assures a good hard coating that will maintain a crater and

give added penetration and better direction to the arc stream.

e) Furnish Slag for Fluxing - The function of the slag is (1) to provide additional

protection against atmospheric contamination, (2) to act as a cleaner and absorb impurities

that are floated off and trapped by the slag, (3) to slow the cooling rate of the molten metal to

allow the escape of gases. The slag also controls the contour, uniformity and general appear-

ance of the weld. This is particularly true in fillet welds.

f) Characteristics for Welding Position - It is the addition of certain ingredients,

primarily titanium compounds, in the coating that makes it possible to weld out-of-position ,

vertically, and overhead. Slag characteristics, primarily surface tension and freezing point,

determine to a large degree the ability of an electrode to be used for out-of-position work.

g) Control of Weld Metal Soundness - Porosity or gas pockets in weld metal

can be controlled to a large extent by the coating composition. It is the balance of certain

ingredients in the coating that have a marked effect on the presence of gas pockets in the

weld metal. The proper balance of these is critical to the soundness that can be produced.

Ferromanganese is probably the most common ingredient used to attain the correctly bal-

anced formula.

h) Specific Mechanical Properties to the Weld Metal - Specific mechanical

properties can be incorporated into the weld metal by means of the coating. High impact

values at low temperature, high ductility, and increases in yield and tensile properties can be

attained by alloy additions to the coating.

i) Insulation of the Core Wire - The coating acts as an insulator so that the core

wire will not short-circuit when welding in deep grooves or narrow openings; coatings also

serve as a protection to the operator when changing electrodes.

3.2.2 Classification of Coating Ingredients - Coating materials can be classified into

the following 6 major groups:


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TECHNOLOGY


LESSON IVCOVERED ELECTRODES FOR

WELDING LOW ALLOY STEELS

AN INTRODUCTION TO LOWALLOY COVERED ELECTRODES




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TABLE OF CONTENTSLESSON IV

COVERED ELECTRODES FOR WELDINGLOW ALLOY STEELS

4.1 LOW ALLOY STEELS ...................................................................... 1

4.2 Consequence of Hydrogen in Low Alloy Steel .................................. 1

4.2.1 Preheat ............................................................................................. 3

4.3 MANUFACTURING LOW HYDROGEN ELECTRODES .................. 3

4.3.1 Storage and Reconditioning.............................................................. 4

4.3.2 Moisture Resistant Coating ............................................................... 4

4.4 AWS SPECIFICATION FOR LOW ALLOY ELECTRODES.............. 5

4.4.1 Effect of Alloying Elements ............................................................... 6

4.4.2 Mechanical Properties (AWS A5.5-96) ............................................. 7

4.4.3 Impact Properties.............................................................................. 8

4.5 SELECTING THE PROPER LOW ALLOY ELECTRODE ................ 8

4.5.1 Service Conditions ............................................................................ 8

4.5.2 Joint Design ...................................................................................... 9

4.5.3 Equipment......................................................................................... 10

4.6 LOW HYDROGEN IRON POWDER ELECTRODES ....................... 11

4.6.1 Atom Arc 7018 (AWS E7018) ........................................................... 11

4.6.2 Atom Arc 7018 Mo (AWS E7018-A1)................................................ 11

4.6.3 Atom Arc 8018N (AWS E8018-C2) ................................................... 12

4.6.4 Atom Arc 8018CM (AWS E8018-B2) ................................................ 13

4.6.5 Atom Arc 8018W (AWS E8018-G).................................................... 13

4.6.6 Atom Arc 9018CM (AWS E9018-B3) ................................................ 14

4.6.7 Atom Arc 9018-B3L (AWS E9018-B3L) ............................................ 14

4.6.8 Atom Arc 10018 (AWS E10018-M) ................................................... 15

4.6.9 Atom Arc 10018MM (AWS E10018-D2) ........................................... 15

4.6.10 Atom Arc 12018 (AWS E12018-M).................................................... 16


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4.6.11 Atom Arc "T" (AWS E11018-M) ......................................................... 16

4.6.12 Atom Arc 9018HT (AWS E9018G) .................................................... 17

4.6.13 Atom Arc 4130 (No AWS Classification) ............................................ 17

4.6.14 Atom Arc 4130 LN (No AWS Classification) ...................................... 17

Appendix A Stick Electrode Data Charts - Atom Arc Electrodes .......................... 19

Appendix B Glossary of Terms ............................................................................. 20

TABLE OF CONTENTSLESSON IV- Con't


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LESSON IV

COVERED ELECTRODES FOR WELDINGLOW ALLOY STEELS

4.1 LOW ALLOY STEELS

Low alloy steels, as discussed in Lesson I, are those steels to that have small amounts of

alloying elements added for specific purposes; i.e., to increase strength, toughness, corrosion

and rust resistance, or to alter the response to heat treatment. Nearly every steel manufacturer

makes a family of low alloy steels that are usually sold under trade names such as Maynari R,

Cor-ten, Man-ten, and many others. Many of the steels are designed to develop their specific

properties such as high strength or toughness in the hot rolled and controlled cooling condition,

rather than by subsequent heat treatment. Other compositions of low alloy steels are designed

to develop specific properties following heat treatments. Examples of these types are U.S.

Steel T-1, Armco Steel SS-100, Great Lakes Steel NA XTRA 100, all of which are quenched

and tempered to reach high strength with good toughness. Covered low alloy welding elec-

trodes are designed, in most cases, to match the properties of the low alloy steels rather than

to match the exact chemical composition of the steel. Exceptions to this are the chromium

molybdenum electrodes that need to contain about the same amounts of the alloy ingredients

as the steel in order to match the properties of the steel.

4.2 CONSEQUENCE OF HYDROGEN IN LOW ALLOY STEEL

One of the reasons that low alloy steels are becoming more popular is because of the exten-

sive research that was conducted in the development of electrodes for welding them. Although

special precautions and care are required in welding the low alloy steels, they can now be

joined with a high degree of reliability. But that was not always so. During World War II when

there was a dramatic increase in the use of high strength low alloy steel, there was also a

corresponding increase in weld defects. It was quickly realized that hardenable steels could

not be welded in the same manner and with the same electrodes as were then commonly used

for welding the lower strength mild steels. Through extensive research, it was found that en-

trapped hydrogen was the culprit in causing weld defects, and the term "hydrogen

embrittlement" became synonymous with red flags warning of impending disaster.

4.2.0.1 When hydrogen bearing compounds such as water, minerals, or chemicals are

present in the electrode coating, as is common with mild steel electrodes, the chemically

combined hydrogen is dissociated into atomic hydrogen by the heat of the welding arc. The

molten weld metal has the capacity to dissolve the atomic hydrogen. However, as soon as the


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Filler Metals


LESSON IV

weld metal solidifies, it loses the ability to hold the hydrogen in solution and the hydrogen is

either expelled into the atmosphere or moves throughout the weld zone. Steel and weld metal

are not as solid as they appear to the naked eye, being filled with tiny submicroscopic pores.

The hydrogen atoms are smaller than the crystalline structure of the steel or the weld metal,

and the hydrogen can move about somewhat freely in the steel, just as air can move through a

filter. The hydrogen atoms move out of the weld metal into the heat affected zone. The heat

affected zone (HAZ) is an area of critical importance in welding, especially in welding high

strength steels.

4.2.0.2 The heat affected zone (See Figure 1) is that area of the weld joint that did not

become molten in the welding process, but underwent a microstructure change as a result of

the heat induced by the arc. This

zone can become a weak link in

the normally very strong joint.

First of all, the grain struc-

ture of the HAZ is less

refined and therefore,

weaker than the sur-

rounding unaffected

base metal or the once

molten weld metal.

And secondly, if the

HAZ is permitted to cool

too rapidly in certain steels,

a hard brittle crystalline struc-

ture, known as Marsenite, is locked

in place. The relatively large pores of

the heat affected zone are a natural collect-

ing place for atomic hydrogen. When two hydrogen atoms meet, they immediately unite to

form molecular hydrogen. The resulting molecules are larger than the crystalline structure of

the metal and can no longer move about freely. As more and more hydrogen atoms come into

the pores, form molecules, and are trapped, tremendous pressure can develop. Mild steel and

lower strength steels are sufficiently plastic to move a little with the hydrogen pressure and not

cause the steel to crack. Steels that have high hardness and high strength do not have suffi-

cient plasticity to move with the pressure, and if enough hydrogen is present, cracking of the

steel occurs.

HEAT AFFECTED ZONE

FIGURE 1

SOLIDIFIED WELD METAL

HEAT AFFECTED ZONE

UNAFFECTED BASE METAL


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LESSON IV

4.2.0.3 This hydrogen caused defect, known as underbead cracking (See Figure 2), begins

in the HAZ making it particularly sinister since the crack is not immediately apparent to the

eye. It occurs after the metal has cooled from about 400°F to room temperature, and it is

sometimes referred to as

"cold cracking". The defect

may occur immediately after

cooling, or it may take hours,

days, or even months before

it happens.

4.2.1 Preheat - Steels

that are highly hardenable by

a rapid cooling in the heat

affected zone require pre-

heat and interpass temperature control.

As preheat is applied to the steel, the

cooling rate of the steel from higher temperatures is slowed. Maintaining a constant tempera-

ture between each welding pass also helps to control this cooling. Slower cooling rates pre-

vent the steel from being excessively hardened and thus, minimizes the chance of underbead

cracking. When this technique is combined with the use of low hydrogen electrodes, a high

degree of reliability can be expected from the welds.

4.3 MANUFACTURING LOW HYDROGEN ELECTRODES

The discovery of hydrogen related weld defects initiated the development of low hydrogen

electrodes. The functions of the coating with low hydrogen electrodes (i.e., shielding, arc

stabilizers, alloy additions, etc.) are much the same as those listed in Lesson III for Mild Steel

Covered Electrodes, but the coating is formulated with ingredients that lack hydrogen in their

chemical composition. This is primarily accomplished by eliminating organic and chemical

compounds high in moisture content. In fact, control of the moisture levels in the coating is

critical in the manufacture and use of low hydrogen electrodes.

4.3.0.1 In addition to eliminating hydrogen in the coating formula, the manufacturing process

entails a high temperature bake cycle. After the coating is extruded onto the core in the same

manner as a mild steel coated electrode, the low hydrogen electrodes are given an initial low

temperature bake (300-400°F), and then rebaked in a separate high temperature oven (800-

900°F) for a specified period of time. This procedure practically eliminates all moisture, and

to guard against the reabsorbing of moisture that is naturally present in the atmosphere, the

BASE METAL

WELD METAL

HEAT AFFECTED ZONE

HYDROGEN INDUCED CRACKS

UNDERBEAD CRACKING

FIGURE 2


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LESSON IV

electrodes are immediately packaged in hermetically sealed metal containers following the

high temperature bake.

4.3.1 Storage and Reconditioning - All low hydrogen electrodes will absorb some

moisture from the air after the electrode container is opened. Therefore, those electrodes that

are not intended for use within a given period of time must be stored in a vented oven and

maintained at a constant temperature.

4.3.1.1 Various structural and military codes allow only specified times of exposure. These

may be anywhere from 30 minutes to 8 hours depending on the electrode alloy, the relative

humidity in the work area, and the critical nature of the application. If the low hydrogen elec-

trodes are exposed to the atmosphere beyond these time limits, they must be scrapped or

reconditioned by rebaking in a vented oven for a specified time at a specific temperature.

4.3.1.2 The recommended storage and rebake temperatures for Atom Arc low hydrogen

electrodes are follows:STORAGE RECONDITIONED

225-300°F 1 hr. @700°F

4.3.2 Moisture Resistant Coating - Moisture absorption is of special concern to end-

users such as shipbuilders and oil rig fabricators who are situated in areas of the world that

have a high level of relative humidity. As the temperature and relative humidity increase, the

chance of absorbing moisture in the low hydrogen coating is greatly increased. To combat this

possibility, major electrode manufacturers have in recent years developed low hydrogen

electrodes with moisture resistant coatings. These coatings low the rate of moisture absorp-

tion in electrodes that have been exposed to the air for extended periods, thus adding an extra

degree of reliability to low hydrogen electrodes.

4.3.2.1 The following graphs (figure 3) give an idea of the effectiveness of a moisture

resistant coating. The tests were conducted on Atom Arc 7018 electrodes. The method of

moisture testing chosen by ESAB is that described in Section 25 of the AWS A5.5-96 Specifi-

cation. This method was chosen because it satisfies the AWS specifications and is sensitive

only to water, making it one of the most accurate and reliable methods of moisture determina-

tion currently in use.

4.3.2.2 The AWS structural code and military specifications allow a maximum of 0.40% and

0.20% moisture content, respectively, for E70XX low hydrogen electrodes. As shown on the

preceding graphs, the Atom Arc 7018 electrode satisfied this low moisture requirement for

exposure times beyond those normally allowed in field use.


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LESSON IV

4.4 AWS SPECIFICATION FOR LOW ALLOY

ELECTRODES A5.5-96

With very few exceptions, low alloy electrodes are made by adding the appropriate alloying

elements to the electrode coating rather than having a core wire that matches the low alloy

steel. Low alloy covered electrodes are classified according to the American Welding Society

filler metal specification A5.5-96. This specification contains the mechanical property require-

EFFECTIVENESS OF MOISTURE RESISTANT COATING - ATOM ARC 7018 ELECTRODES

FIGURE 3

.40

.30

.20

.10

01 2 4 8 12 24 36 48 96Exposure Time (hours)

1 2 4 8 12 24 36 48 96Exposure Time (hours)

.40

.30

.20

.10

0

1 2 4 8 12 24Exposure Time (hours)

.40

.30

.20

.10

0

Moisture atZero Hours .09



70°F - 70% Relative Humidity




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Filler Metals


LESSON IV

ments and stress relieved condition, the chemical requirements, and the weld metal sound-

ness requirements. Electrodes are classified under this specification according to the me-

chanical properties and chemical composition of the weld metal, the type of covering, and the

welding position of the electrode. The classification of the electrode is designated by the

manufacturer according to the results of his own tests. The manufacturer, thereby, guarantees

his electrode to meet the requirements of the AWS specification.

4.4.0.1 The letter-number designations for low alloy electrode classifications mean much

the same as with mild steel electrodes, except that the major alloy composition is indicated by

a letter-number suffix. For example, E7018-A1 indicates an electrode (letter E); with a mini-

mum of 70,000 psi tensile strength (70); is weldable in all positions (1); is iron powder low

hydrogen (8); and contains nominally 1/2% molybdenum (A1). The full list of nominal alloy

compositions for this specification is contained in Table 1.

4.4.1 Effect of Alloying Elements

4.4.1.1 Molybdenum - When mild steel weld metal is stress relieved, the yield point is

lowered 3,000 psi or more and the tensile strength is also lowered 3,000 psi or more. When

1/2% of molybdenum is added to the weld, both the yield point and the tensile strength remain

constant from the as-welded to the stress relieved condition. The presence of molybdenum

also increases the tensile strength of the weld metal.

TABLE 1. Nominal Alloy Designations for AWS A5.5 Specification

A1 1/2% Molybdenum

B1 1/2% Chromium, 1/2% Molybdenum

B2 1-1/4% Chromium, 1/2% Molybdenum

B2L Low Carbon version of B2 type. Carbon content is 0.05% or less

B3 2-1/4% Chromium, 1% Molybdenum

B3L Low Carbon version of B3 type. Carbon content is 0.05% or less

B4L 2% Chromium, 1/2% Molybdenum, low carbon (0.05% or less)

B5 1/2% Chromium, 1.1% Molybdenum

C3 1% Nickel

C1 2% Nickel

C2 3% Nickel

D1 1-1/2% Manganese, 1/3% Molybdenum

D2 1-3/4% Manganese, 1/3% Molybdenum

M Conforms to compositions covered by Military specifications.

G Needs only a minimum of one of the elements listed in the AWS A5.5 Table

for Chemical Requirements.


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LESSON IV

4.4.1.2 Chromium - When chromium is added to the weld metal, the corrosion and high

temperature scaling resistance are increased. The combination of chromium and molybde-

num allows the weld metal to retain high strength levels at medium high temperatures.

4.4.1.3 Nickel - Mild steel weld metal usually becomes brittle at temperatures below -20°F.

The addition of 1-3% nickel to the weld metal enables the weld metal to remain tough at con-

siderably lower temperatures. The presence of the nickel also makes the weld metal more

resistant to cracking at room temperature.

4.4.1.4 Manganese - The presence of 1-1/2% to 2% manganese in weld metal increases

the tensile strength and when 1/3% molybdenum is added in combination, the high strength

weld metal is crack resistant.

4.4.1.5 It should be noted that the A5.5-96 specification covers not only the low alloy low

hydrogen electrodes, but also low alloy versions of the cellulosic, titania, and iron oxide type

electrodes. A full list of all the electrodes covered by this specification is presented in Table 2.

TABLE 2. Electrode Classifications of AWS A5.5 Specification

E7010-A1 E8018-B2 E9015-B3L E11018-M

E7011-A1 E8018-B2L E9016-B3 E12018-M

E7015-A1 E8015-B4L E9018-B3

E7016-A1 E8016-B5 E9018-B3L EXX10-G

E7018-A1 E8016-C1 E9015-D1 EXX11-G

E7020-A1 E8018-C1 E9018-D1 EXX13-G

E7027-A1 E8016-C2 E9018-M EXX15-G

E8018-C2 EXX16-G

E8016-B1 E8016-C3 E10015-D2 EXX18-G

E8018-B1 E8018-C3 E10016-D2 E7020-G

E8015-B2L E10018-D2

E8016-B2 E9015-B3 E10018-M

4.4.2 Mechanical Properties (AWS A5.5-96) - Since many low alloy steels require

some post-weld heat treatment to relieve the internal stresses generated from the welding

process, physical testing on the weld metal of most low alloy electrodes is required to be

performed after the specimen has been stress-relieved. Only the E8016-C3, E8018-C3,

E9018-M, E11018-M, and E12018-M types are permitted to be tested in the as-welded condi-

tion for classification purposes.


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LESSON IV

4.4.3 Impact Properties - Since many low alloy steels are developed for low tempera-

tures service, impact properties of the weld metal designed to join these steels are very impor-

tant. Except for those types already mentioned, all impact testing is performed on specimens

after they have been stress-relieved. Table 3 lists the minimum charpy v-notch impacts re-

quired in the A5.5 specification.

TABLE 3. Impact Requirements for AWS A5.5 Specification

AS WELDED MINIMUM REQUIREMENT STRESS-RELIEVED

E8016-C3 )------- 20 ft.-lbs. @-40°F.

E8018-C3 )

E9018-M ) ( E9015-D1

E10018-M ) ( E9018-D1

E11018-M )------- 20 ft.-lbs. @-60°F. -------- ( E10015-D2

E12018-M ) ( E10016-D2

( E10018-D2

( E8016-C1

20 ft.-lbs. @-75°F. -------- ( E8018-C1

( E8016-C2

20 ft.-lbs. @-100°F.------- ( E8018-C2

Impact values for all other classifications are not required.

4.5 SELECTING THE PROPER LOW ALLOY ELECTRODE

As stated earlier, low alloy electrodes are often selected to match the properties of the steel to

be welded rather than matching the exact chemical composition of the steel. These properties

(i.e., strength, toughness, creep, and corrosion resistance) reflect the type of service for which

the steel is intended. The letter-number suffix of the electrode classification gives an indication

of that service. Whenever possible, the electrode should be selected on the basis of the

appropriate strength levels and the intended service of the weldment.

4.5.1 Service Conditions - The large family of "proprietary" steels that are sold in the as

rolled, controlled, cooled condition have a 50,000 psi minimum yield point and 70,000 psi

minimum tensile strength. Electrodes that deposit low hydrogen weld metal of those strength

levels are used to weld them.


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LESSON IV

4.5.1.1 Some of the low alloy high strength steels are intended for use at subzero tempera-

tures. Nickel bearing low hydrogen electrodes (C1, C2, C3 types) are available for such low

temperature applications.

4.5.1.2 Chromium molybdenum low alloy steels are used for moderately high temperature

service. Piping, tubing, boilers, etc., that are used extensively in power generating plants, are

fabricated from these steels. Chrome-moly low hydrogen electrodes (B1, B2, B3, etc.) are

produced to weld these steels.

4.5.1.3 Many bridges and outdoor structures are constructed from "weathering" grade

steels. These are low alloy steels that, on exposure to the atmosphere, develop a thin, tightly

adhering layer of rust that prevents further rusting and eliminates the need for painting. Low

alloy electrodes with additions of chromium and copper are available for welding these steels.

4.5.1.4 Quenched and tempered low alloy steels usually develop high strength with good

toughness. These types are used where substantial savings in the weight of the structure is

important. Quite often, but not exclusively, these steels are used by the military. One of the

more exotic applications for quenched and tempered low alloy steels is in the fabrication of the

pressure hulls for nuclear submarines. The "M" series of high tensile low hydrogen electrodes

is intended to weld these steels.

4.5.1.5 High tensile line pipe for the transmission of oil and gas is being used with greater

frequency today. Low alloy cellulosic electrodes of the 7010 and 8010 variety are used for

field welding.

4.5.2 Joint Design - In fillet welding of high strength quenched and tempered steels, toe

cracking alongside the welds (see Figure 4) is frequently a problem. The toe cracking is

caused by the high strength weld metal having a higher yield point and tensile strength than the

steel.

4.5.2.1 When the weld area shrinks on

cooling from the welding temperature, something

must give, and because the yield and strength

levels of the steel are lower than those of the

weld metal, cracking occurs in the heat affected

zone of the steel. The solution to this problem is

to use a lower strength weld metal and increase

the fillet size to meet the weld joint strength requirements.

HEAT AFFECTEDZONE

CRACK AT TOEOF WELD

WELD METAL

BASEMETAL

TOE CRACKING

FIGURE 4


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Filler Metals


LESSON IV

With a somewhat lower strength weld metal as the filler, the yield point of the weld metal is

reached during the shrinkage on cooling. The weld metal stretches without overloading in the

heat affected zone of the steel and there is no cracking.

4.5.3 Equipment - The electrode selected will operate only on the appropriate power

source. Table 4 lists the type of current for which each class of electrode is designed.

TABLE 4. Current Requirements for AWS Electrode Classes

Electrode Class Current

EXX10-X* DCRP

EXX11-X AC or DCEP

EXX13-X AC or DC either polarity

EXX15-X DCEP

EXX16-X AC or DCEP

EXX18-X AC or DCEP

EXX20-X AC or DCEN (horizontal fillet)

AC or DC either polarity (flat)

EXX27-X AC or DCEN (horizontal fillet)

AC or DC either polarity (flat)

* "X" indicates a variable in the classification.


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LESSON IV

4.6 ESAB ATOM ARC LOW HYDROGEN IRON POWDER

ELECTRODES - FEATURES AND DATA

4.6.1 Atom Arc 7018 (AWS E7018) - Although this electrodes is really of the mild steel

category and classification, the mechanical properties of the weld metal are sufficient to meet

the similar properties of the 50,000 psi yield and 70,000 psi tensile strength steels. Usually,

preheat and interpass temperature control of those steels is not necessary when welding with

Atom Arc 7018, although heavier thicknesses of steel may require some preheat. Common

applications include: welding carbon steels, high sulfur steels, enameling steels, and some

low alloy, high tensile steels.

Typical Mechanical Properties of Weld MetalAs Welded Stress-Relieved

Yield Point, psi 68,500 62,000

Tensile Strength, psi 75,000 72,000

% Elongation (2") 31 32

% Reduction 75.5 77

Charpy V-Notch Impact @72°F. 125 ft.-lbs. 130 ft.-lbs.

@-20°F. 70 ft.-lbs. 75 ft.-lbs.

Typical Chemical Composition of Weld Metal

C Mn Silicon

0.06% 1.10% 0.50%

4.6.2 Atom Arc 7018 Mo (AWS E7018-A1) - This electrode, which deposits 1/2%

molybdenum weld metal, is useful in welding power piping and pressure vessels of

molybdenum bearing steels designed for use at elevated temperatures. Typical applications

include: welding of low carbon and carbon-moly tubes and piping, forged alloy steel pipe

flanges, fittings and valves for high temperature service, carbon-moly steel boiler and

superheater tubes, manganese-moly and manganese-moly-nickel pressure vessel plates, high

strength structural steel and steel castings for highway service.


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LESSON IV

Typical Mechanical Properties of Weld MetalAs Welded* Stress-Relieved*





@-10°F. 85 ft.-lbs. 85 ft.-lbs.

@-40°F. 70 ft.-lbs. 70 ft.-lbs.


C Mn Ni

0.04% 1.06% 2.37%

4.6.3 Atom Arc 8018N (AWS E8018-C2) - 8018N electrodes with 3% nickel are usually

used to weld 3% nickel steels for low temperature service. It has solved many weld cracking

problems by its weld crack resistance, as well as remaining tough at temperatures as low as -

100°F. Typical applications include: welding of piping for low temperature service, carbon and

low alloy steel forgings and ferritic steel castings for high pressures at low temperatures, high

strength steel castings for structural purposes, carbon steel forgings for railroad use and

concrete reinforcement bars.

Typical Mechanical Properties of Weld Metal

As Welded Stress-Relieved




% Reduction of Area 55 74

Charpy V-Notch Impacts @72°F. 110 ft.-lbs. 112 ft.-lbs.

@0°F. 91 ft.-lbs. 93 ft.-lbs.

@-40°F. 73 ft.-lbs. 63 ft.-lbs.

@-100°F. 35 ft-lbs. 30 ft.-lbs.


C Mn Si Ni

0.5% 0.84% 0.37% 3.30%


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LESSON IV

4.6.4 Atom Arc 8018CM (AWS E8018-B2) - This 1-1/4% chrome, 1/2% moly electrode

deposits weld metal that retains high strength at temperatures up to 600°F. The 8018CM

electrodes are used to weld the 1/2% chrome-1/2% moly, 1% chrome-1/2% moly steels, as

well as the 1-1/4% chrome-1/2% moly power piping, boiler tubing, plates and castings. Many

of the fossil fired steam boilers in electric generating plants in the United States have been

welded with this electrode and its relative 9018CM.


Stress-Relieved Stress-Relieved8 hrs. @1150°F. 8 hrs. @1350°F.




% Reduction of Area 60.7 79.1

Charpy V-Notch Impacts @30°F. 64 ft.-lbs. 127 ft-lbs.


C Mn Si Ni Mo

0.06% 1.10% 0.40% 1.00% 0.50%

4.6.5 Atom Arc 8018W (AWS E8018-G) - The balanced alloy combination of chromium,

nickel and copper of this electrode causes the weld metal to "weather" similarly to the

weathering grade steels when exposed to the atmosphere. The inform color blend of this weld

metal with the weathered steel makes these electrodes the ideal choice when architectural

appearance and weld integrity is important.

Typical Mechanical Properties of Weld Metal Stress-Relieved

As Welded 1 hr. @1025°F.





Charpy V-Notch Impacts @-60°F. 63 ft-lbs. 44 ft.-lbs.


C Mn Si Ni Mo

0.05% 1.11% 0.32% 1.70% 0.28%


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LESSON IV

4.6.6 Atom Arc 9018CM (AWS E9018-B3) - These 2-1/4% chrome - 1% moly electrodes

are used to weld and match the composition of the 2-1/4% chrome - 1% moly steels in

pressure piping and power boilers. The chromium-molybdenum content of the weld metal

helps retain appreciable strength at temperatures up to 800°F.


Stress-Relieved Stress-Relieved1 hr. @1275°F. 2 hrs. @1350°F.






C Mn Si Ni Mo

0.05% 0.75% 0.60% 2.20% 1.05%

4.6.7 Atom Arc 9018-B3L (AWS E9018-B3L) - The low carbon content of this 2-1/4%

chrome - 1% moly electrode makes the weld metal more crack resistant in heavy sections and

allows lower preheat and interpass temperatures to be used. Typical applications include:

high temperature power piping, boilers, heat-exchanger and condenser tubes, pressure vessel

plates and steel castings for high temperature pressure service.


Stress-Relieved Stress-Relieved8 hrs. @1150°F. 8 hrs. @1350°F.




% Reduction of Area 67.6 73



C Mn Si Ni Mo

0.02% 0.74% 0.61% 2.47% 1.10%


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LESSON IV

4.6.8 Atom Arc 10018 (AWS E10018-M) - The manganese-nickel-molybdenum

composition of Atom Arc 10018 is used mostly on thinner sections of quenched and tempered

low alloy steels where 100,000 psi tensile strength, along with good ductility and toughness at

temperatures as low as -60°F, are required. This product is used primarily for military

applications.

Typical Mechanical Properties of Weld Metal Stress-RelievedAs Welded 1 hr. @1025°F.





Charpy V-Notch Impact @-60°F. 33 ft.-lbs. 22 ft.-lbs.


C Mn Si Ni Mo

0.05% 1.58% 0.40% 1.50% 0.30%

4.6.9 Atom Arc 10018MM (AWS E10018-D2) - This electrode, with its combination of

manganese and molybdenum, was originally developed during World War II to repair and

fabricate manganese-molybdenum castings and armor plate. It is used to weld similar

composition low alloy steels, as well as heat treatable steels comparable to hardenable steels.


Stress-RelievedAs Welded 2 hrs. @1100°F.






@0°F. 55 ft.-lbs. 50 ft.-lbs.

@-40°F. 38 ft.-lbs. 34 ft.-lbs.


C Mn Si Mo

0.09% 1.77% 0.68% 0.35%


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LESSON IV

4.6.10 Atom Arc 12018 (AWS E12018-M) - This electrode deposits high strength weld

metal in both the as welded and stress-relieved conditions, which is required for welding many

of the high strength quenched and tempered steels. It is used to weld steels with 120,000 psi

tensile strength in applications, such as welding carbon and high strength alloy steel forgings

for railroad equipment, high strength steel castings for structural work, and steel castings for

highway bridges.

Typical Mechanical Properties of Weld Metal Stress-RelievedAs Welded 1 hr. @1025°F.






@-60°F. 32 ft.-lbs. 31 ft.-lbs.


C Mn Si Cr Ni Mo

0.05% 1.90% 0.25% 0.85% 2.00% 0.50%

4.6.11 Atom Arc "T" (AWS E11018-M) - Atom Arc "T" electrodes were developed for

welding U.S. Steels T-1 steel, which is quenched and tempered to high strength and ductility. It

has since been used to weld all of the quenched and tempered steels, including HY-80, the

steel used for the pressure hulls of nuclear submarines.


Stress-RelievedAs Welded 1 hr. @1025°F.






@0°F. 55 ft.-lbs. 50 ft.-lbs.

@-40°F. 48 ft.-lbs. 42 ft.-lbs.

@-60°F. 41 ft.-lbs. 26 ft.-lbs.


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Filler Metals


LESSON IV


C Mn Si Cr Ni Mo

0.06% 1.53% 0.27% 0.31% 1.88% 0.43%

4.6.12 Atom Arc 9018HT (AWS E9018G) - As the HT indicates, this electrode is intended

for heat treated applications. It deposits weld metal with properties that match chromium-

molybdenum steel castings and is also useful in the repair and rebuilding of hot forging dies.


Quenched @1700°F. Quenched @1600°F.Tempered @1275°F. Tempered @900°F.



% Elongation (2") 20 12.5



C Mn Si Cr Mo

0.14% 0.80% 0.65% 2.30% 1.00%

4.6.13 Atom Arc 4130 (No AWS Classification) - This composition was developed to

weld heat treatable steels such as SAE4130, providing a weld metal that responds similarly to

the heat treatment.








C Mn Si Cr Ni Mo

0.18% 1.25% 0.40% 2.50% 1.28% 0.20%


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LESSON IV

4.6.14 Atom Arc 4130 LN (No AWS Classification) - This alloy combination has less

than 1% nickel so that it may be used safely to weld oil field equipment that handles "sour"

(high sulfur) crude oil. The weld metal is hardenable by quenching and tempering similar to

SAE4130 steel.








C Mn Si Cr Ni Mo

0.26% 1.25% 0.47% 0.49% 0.80% 0.16%

4.6.15 Additional information on Atom Arc Low Hydrogen, Low Alloy electrodes is

contained in the Atom Arc product catalog and the Atom Arc handbook for welding low alloy

high tensile steels, published by ESAB.


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LESSON IV

APPENDIX ASTICK ELECTRODE DATA CHARTS

ATOM ARC ELECTRODES

TYPES E7018, E8018, E9018, E10018, E11018, AND E12018

ELECTRODE DEPOSITION EFFICIENCYELECTRODE DEPOSITION EFFICIENCYDIAMETER AMPS RATE lbs/hr % DIAMETER AMPS RATE lbs/hr %

3/32 70 1.37 70.50 3/16 200 4.85 76.40

90 1.65 66.30 250 5.36 74.60

110 1.73 64.40 300 5.61 70.30

1/8 120 2.58 71.60 7/32 250 6.50 75.00

140 2.74 70.90 300 7.20 74.00

160 2.99 68.10 350 7.40 73.00

5/32 140 3.11 75.00 1/4 300 7.72 78.00

170 3.78 73.50 350 8.67 77.00

200 4.31 73.00 400 9.04 74.00

CHART TO CONVERT ENGLISHELECTRODE DIMENSIONS TO METRIC

EQUIVALENTS

DIAMETER LENGTH

Inches mm Inches mm

3/32 2.4 12 3001/8 3.2 14 350

5/32 4.0 14 3503/16 4.8 14/18 350/4507/32 5.6 18 4501/4 6.4 18 450

5/16 8.0 18 450

STUB"LOSS CORRECTION TABLE FOR COATED

ELECTRODE EFFICIENCY INCLUDING STUB LOSS

ELEC. DEPOSITION 2" 3" 4" 5"

LENGTH EFFICIENCY STUB STUB STUB STUB

60% 50.0% 45.0% 40.0% 35.0%

65% 54.2% 48.7% 43.3% 37.9%

12" 70% 58.3% 52.5% 46.6% 40.8%

75% 62.5% 56.2% 50.0% 43.7%

80% 66.6% 60.0% 53.3% 46.6%

60% 51.4% 47.1% 42.8% 38.5%

65% 55.7% 51.1% 46.4% 41.8%

14" 70% 60.0% 55.0% 50.0% 45.0%

75% 64.3% 58.9% 53.6% 48.2%

80% 68.5% 62.8% 57.1% 51.4%

60% 53.3% 50.0% 46.6% 43.3%

65% 57.7% 54.2% 50.5% 46.9%18" 70% 62.2% 58.3% 54.4% 50.5%

75% 66.6% 62.5% 58.3% 54.2%

80% 71.1% 66.6% 62.2% 57.7%


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DEPOSITION EFFICIENCY DATA-LOW ALLOY, IRON POWDER ELECTRODES


LESSON IV

APPENDIX B

LESSON IV - GLOSSARY OF TERMS

Quench - The rapid cooling of steel from a temperature above the transformationtemperature. This results in hardening of the steel.

Temper - Reheating of steel to a temperature below the transformation temperaturefollowing the quenching of steel. This usually lowers the hardness and

strength and increases the toughness of the steel.

StressRelieved

- The reheating of a weldment to a temperature below the transformationtemperature and holding it for a specified period of time. A frequently usedtemperature and time is 1150°F. for 1 hr. per inch of thickness. Thisreheating removes most of the residual stresses put in the weldment by theheating and cooling during welding.

TransformationTemperature

- The temperature at which the crystal structure of the steel changes,usually about 1600°F.

Heat AffectedZone

- The area of the base metal that did not become molten in the weldingprocess, but did undergo a microstructure change as a result of the heatinduced into that area. If the HAZ in hardenable steels is cooled rapidly, thearea becomes excessively brittle.

UnderbeadCracking

- A weld defect that starts in the heat affected zone and is caused byexcessive molecular hydrogen trapped in that region. It is sometimesreferred to as cold cracking, since it occurs after the weld metal has cooled.

Low HydrogenElectrodes

- Stick electrodes that have coating ingredients that are very low inhydrogen content. The low hydrogen level is achieved primarily by keeping

the moisture content of the coating to a bare minimum.

WeatheringSteel

- Low alloy steel that is specially formulated to form a thin tightly adheringlayer of rust. This initial layer prevents further rusting and thus, the need topaint the steel is eliminated. The main alloys in this steel are copper andchromium.

ToeCracking

- A weld defect that occurs at the toe of the weld metal. The cracking

occurs when the weld metal does not stretch with the base metal becausethe yield and tensile strength of the weld metal is greater than the steel.


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Filler Metals


TECHNOLOGY


LESSON VWELDING FILLER METALS

FOR STAINLESS STEELS




Welding












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Filler Metals


LESSON V


TABLE OF CONTENTSLESSON V

WELDING FILLER METALSFOR STAINLESS STEELS

5.1 INTRODUCTION TO STAINLESS STEEL ...................................... 1

5.2 DIFFERENCES IN STAINLESS AND CARBON STEELS .............. 3

5.3 STAINLESS STEEL TYPES ............................................................ 5

5.4 AUSTENITIC STAINLESS STEELS ................................................ 6

5.4.1 Carbide Precipitation ........................................................................ 6

5.4.2 Ferrite in Austenitic Stainless Steels .................................................. 7

5.5 CALCULATION OF FERRITE CONTENT IN STAINLESS STEEL . 8

5.6 SPECIAL FERRITE REQUIREMENT IN STAINLESS STEELELECTRODES ................................................................................. 10

5.7 MARTENSITIC STAINLESS STEELS ............................................. 10

5.8 FERRITIC STAINLESS STEELS ..................................................... 11

5.9 DUPLEX STAINLESS STEELS ...................................................... 12

5.10 ELECTRODE SELECTION ............................................................. 12

5.11 WELDING DISSIMILAR STEELS .................................................... 13

5.12 STAINLESS STEEL ELECTRODES AND FILLER METALS ......... 16

5.12.1 Covered Stainless Electrodes............................................................ 16

5.12.2 Arcaloy Lime Coated Electrodes ....................................................... 17

5.12.3 Arcaloy AC-DC Titania Coated Electrodes ........................................ 17

5.12.4 Arcaloy Plus Electrodes ..................................................................... 17

5.13 ARCALOY COVERED ELECTRODE PROPERTIESAND APPLICATIONS ....................................................................... 18

5.13.1 Arcaloy 308L and 308L Plus .............................................................. 18


5.13.3 Arcaloy 309 Cb.................................................................................. 18


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Filler Metals


LESSON V


5.13.4 Arcaloy 309MoL ................................................................................ 19

5.13.5 Arcaloy 310 ....................................................................................... 19

5.13.6 Arcaloy 310 Cb.................................................................................. 19

5.13.7 Arcaloy 310Mo .................................................................................. 19

5.13.8 Arcaloy 312 ....................................................................................... 19


5.13.10 Arcaloy 316LF5 ................................................................................. 20


5.13.12 Arcaloy 318 ....................................................................................... 20

5.13.13 Arcaloy 320 and 320LR ..................................................................... 20

5.13.14 Arcaloy 347 and 347 Plus .................................................................. 21

5.13.15 Arcaloy 410 ....................................................................................... 21

5.14 ARCALOY BARE STAINLESS STEEL ELECTRODES ................. 21

5.15 APPLICATIONS AND COMPOSITIONS OF ARCALOYBARE STAINLESS ELECTRODES ................................................ 22

5.15.1 Arcaloy ER308L ................................................................................ 22

5.15.2 Arcaloy ER308LSi ............................................................................. 22

5.15.3 Arcaloy ER309L ................................................................................ 22

5.15.4 Arcaloy ER310 .................................................................................. 22

5.15.5 Arcaloy ER312 .................................................................................. 23

5.15.6 Arcaloy ER316L ................................................................................ 23

5.15.7 Arcaloy ER316LSi ............................................................................. 23

5.15.8 Arcaloy ER347 .................................................................................. 23

5.16 CORE-BRIGHT STAINLESS STEEL FLUX COREDELECTRODES ................................................................................. 23

5.17 CORE-BRIGHT STAINLESS STEEL FLUX COREDELECTRODE APPLICATIONS AND PROPERTIES ....................... 24

5.17.1 Core-Bright 307................................................................................. 24

5.17.2 Core-Bright 308 Mo ........................................................................... 24

5.17.3 Core-Bright 308LTo ........................................................................... 24

5.17.4 Core-Bright 309L ............................................................................... 25

5.17.5 Core-Bright 316L ............................................................................... 25

TABLE OF CONTENTSLESSON V - Con't.


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LESSON V


5.17.6 Core-Bright 347................................................................................. 25

5.18 FERRITE CONTENT OF CORE-BRIGHT WELD METALS ............ 25

5.19 SHIELD-BRIGHT & SHIELD-BRIGHT X-TRA

STAINLESS STEEL FLUX CORED ELECTRODES ...................... 26

5.20 SHIELD-BRIGHT & SHIELD-BRIGHT X-TRA STAINLESS STEEL

FLUX CORED ELECTRODE APPLICATIONS & PROPERTIES ... 265.20.1 Shield-Bright 308L ............................................................................. 26

5.20.2 Shield-Bright 309L ............................................................................. 27

5.20.3 Shield-Bright 309LMo ........................................................................ 27

5.20.4 Shield-Bright 316L ............................................................................. 27

5.20.5 Shield-Bright 317L ............................................................................. 28

5.20.6 Shield-Bright 347............................................................................... 28

5.21 ARCALOY NICKEL ALLOY COVERED WELDING ELECTRODES -FEATURES AND DATA .................................................................... 29

5.21.1 Arcaloy 9N10 Nickel-Copper ............................................................. 29

5.21.2 Arcaloy 8N12 Nickel-Chromium-Iron .................................................. 29

5.21.3 Arcaloy Ni-9 ....................................................................................... 30

5.21.4 Arcaloy Ni-12 ..................................................................................... 31

5.22 ELECTRODES FOR WELDING CAST IRON .................................. 32

5.22.1 Nickel-Arc 55 ..................................................................................... 32

5.22.2 Nickel-Arc 550................................................................................... 33

5.22.3 Nickel-Arc 99 ..................................................................................... 33

5.22.4 Nicore 55 .......................................................................................... 33

5.22.5 Cupro Nickel Electrodes .................................................................... 34

Appendix A - GLOSSARY OF TERMS .................................................................. 35

TABLE OF CONTENTSLESSON V - Con't.


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Filler Metals


WELDING FILLER METALS FORSTAINLESS STEELS

5.1 INTRODUCTION TO STAINLESS STEEL

Stainless steel, introduced commercially during the early 1930's, presented industry with a new"wonder metal" with its shiny surface and ability to resist rust and corrosion. This new steel

alloy also presented welding problems that had not been previously encountered. It took many

years of research and experimentation to develop successful welding filler metals and welding

procedures for this "rustless iron" as it was then called.

5.1.0.1 Most of us think of stainless as an attractive metal used for trim on our stoves and

automobiles, or as bright, easy-to-clean cooking utensils and cutlery. Besides being used for

its corrosion resisting properties, however, stainless steel is used for low temperature applica-

tions, and for applications where its resistance to scaling at high temperatures is important.

5.1.0.2 Stainless steel is basically an alloy of iron and chromium. As the amount of chro-

mium added to a steel alloy is increased, the corrosion resistance increases until the amount

of chromium reaches 11% to 12%, at which point it is considered a stainless steel. The graph

in Figure 1 shows how the amount of chromium affects the rate of corrosion in a semi-rural,

outdoor air environment. Corrosion rate will vary with the corrosive media to which the stain-

less steel is exposed and with the type of stainless employed.

LESSON V

MILD STEEL

STAINLESS STEEL

PERCENT CHROMIUM

2 4 6 8 10 12 14

.001

.0008

.0006

.0004

.0002

CORROSION RATE VERSUS PERCENT CHROMIUMOUTDOOR ATMOSPHERE, SEMI-RURAL ENVIRONMENT

FIGURE 1


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Filler Metals

© COPYRIGHT 2000 THE ESAB GROUP,

LESSON V

5.1.0.3 The mechanism by which chromium imparts corrosion resistance to steel has been

well established. Essentially, the chromium combines with oxygen of the atmosphere to form a

stable non-metallic oxide film on the surface of the steel. This film protects the steel by acting

as a protective coating. As the chromium content of the steel increases, the tenacity, imper-

meability and strength of this film increases, imparting greater and greater corrosion resis-

tance. This film is too thin to be seen. What we do see is the shiny, unoxidized steel just below

this film.

5.1.0.4 In Lesson I we learned that the application of heat to metals can change the micro-

structure and thereby, the properties of that metal. The fabricator of ordinary carbon steel

understands that successful welds depend upon how that material behaves under the heat of

the arc. With that information as a guide, welds can be produced that satisfy the mechanical

requirements of the welded joint. With stainless steel, however, other aspects such as preser-

vation of corrosion resistance and heat resistance must also be considered.

5.1.0.5 Stainless steel may be welded by most of the common arc welding processes.

Shielded metal-arc welding with coated electrodes is still probably the most widely used

process. Other commonly used processes are flux cored arc welding, gas metal-arc welding,

gas tungsten-arc welding and submerged arc welding as discussed in Lesson II.

5.1.0.6 The cost of stainless steel is approximately six times that of mild steel. For this

reason, it is important that the proper electrodes or filler metals are selected and the proper

welding procedures are followed to minimize rework or scrap losses due to faulty welds. An

understanding of the peculiarities of the four types of stainless steel, and how they compare to

mild or carbon steels, will help to avoid costly mistakes.

5.1.0.7 There are four primary grades of stainless steel: austenitic, martensitic, ferritic, and

duplex. The names are metallurgical terms derived from the crystal structure of the steel at

room temperature and will be covered in more detail later in this lesson. Figure 2 shows the

basic differences and the composition of the four types.

TYPE RANGE OF ALLOYING ELEMENTS

CHROMIUM NICKEL

AUSTENITIC 16 - 30% 8 - 40%MARTENSITIC 11 - 18% 0 - 5%FERRITIC 11 - 30% 0 - 4%DUPLEX 18 - 28% 4 - 8%

MAJOR STAINLESS STEEL ALLOYING ELEMENTS

FIGURE 2


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LESSON V

5.1.0.8 That group of stainless steels that contain both chromium and nickel (austenitic

grade) is more readily and satisfactorily welded than those that contain less than 5% nickel

(martensitic and ferritic grades). Weld joints produced in austenitic stainless steels are strong,

ductile and tough in their as-welded condition. They do not normally require preheat or post

weld heat treatment. On the other hand, the martensitic and ferritic stainless steels are charac-

terized by hardness or brittleness after welding, and preheat and post-heating is necessary to

improve their properties.

5.1.0.9 Austenitic stainless is commonly referred to as the "chrome-nickel" type and the

martensitic and ferritic steels are commonly called the "straight chrome" types.

5.2 DIFFERENCES IN STAINLESS AND CARBONSTEELS

The behavior of stainless steel in the heat of the arc differs from that of mild steel. Figure 3

shows that the rate of expansion of the chromium-nickel types is about 50% greater than that

of carbon steel. This means that distortion from warping must be compensated for to a

greater extent.

CARBONSTEEL

CHROMIUM-NICKELTYPES

STRAIGHTCHROMIUM

TYPES

.020 .040 .060 .080 .100 .120INCHES EXPANSION PER FOOT

1000°F TEMPERATURE RISE

RATE OF EXPANSION

FIGURE 3

5.2.0.1 When welding an austenitic stainless steel to a carbon steel, the different rates of

expansion can cause cracking due to internal stresses unless the proper electrode and weld-

ing procedure is used. The expansion of the straight chromium types is about the same as or

slightly less than that of carbon steels.


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LESSON V

5.2.0.2 The melting temperature of all stainless steels are lower than that of carbon steel as

shown in Figure 5, and both chrome-nickel and straight chrome types are much more fluid in

the melted state. Therefore, less heat (welding current) is required to weld stainless steels

compared to carbon steels.

5.2.0.3 The electrical resistance of both the chrome-nickel and the straight chrome types is

considerably higher than that of the plain carbon steels as shown in Figure 5. This higher

resistance creates more resistance heating in the stainless steel electrode and in the base

plate. Lower welding current or amperage is required to avoid overheating the electrode. The

electrical resistance of the chrome-nickel alloys is about six times that of carbon steel and may

be substantially higher if the stainless is cold-worked. The straight chrome types have electri-

cal resistances varying from three to six times that of carbon steel.

CARBONSTEEL


STRAIGHTCHROMIUM

TYPES

2000 2250 2500 2750 3000DEGREES FAHRENHEIT

MELTING TEMPERATURES

FIGURE 4

MICROHMS/SQ 10 20 30 40 50 60 70 80CM/CM AT 20° C.

ELECTRICAL RESISTANCE

FIGURE 5

CARBONSTEEL


STRAIGHTCHROMIUM

TYPES


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Filler Metals


LESSON V

5.2.0.4 The chrome-nickel stainless alloys conduct heat only 40% to 50% as fast as carbon

steel and in the straight chrome types, heat conductivity is 50% to 65% that of carbon steel as

shown in Figure 6. This means that the heat remains in the vicinity of the arc for a longer

period of time instead of being dispersed throughout the weldment rapidly, as it does when

welding materials of high thermal conductivity. This is another reason that lower amperages

are required to weld these steels.

CARBONSTEEL


STRAIGHTCHROMIUM

TYPES

AT 20° - 100° C .020 .040 .060 .080 .100 .120CAL/SEC/SQ CM

THERMAL CONDUCTIVITY

FIGURE 6

5.3 STAINLESS STEEL TYPES

As already mentioned, there are three principal categories of stainless steels: austenitic,

martensitic, and ferritic. The names are derived from the crystalline structure of the steel

normally found at room temperature. When low carbon steel is heated above 1550°F, the

atoms of the steel are rearranged from the structure called ferrite at room temperatures to the

crystal structure called austenite. On cooling, the low carbon steel atoms return to their original

structure — ferrite. The high temperature structure, austenite, is non-magnetic, plastic and has

lower strength and greater ductility than the room temperature form of ferrite.

5.3.0.1 When more than 17% chromium and 7% nickel are added to the steel, the high

temperature crystalline structure of the steel — austenite, is stabilized so that it persists at all

temperatures from the very lowest to almost melting. This alloy combination is the basis for the

austenitic category of stainless steels . Many alloy additions are made to that base as modifi-

cations for different service requirements.


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LESSON V

5.3.0.2 When certain alloy steels are cooled rapidly from above the transformation tempera-

ture, a very hard brittle phase occurs. This phase is called martensite. Steels that contain 5-

15% chromium have this special characteristic. Unless special care is used in welding such

steels, they become crack sensitive. These are the martensitic stainless steel alloys.

5.3.0.3 When more than 16% chromium is added to the steel, the room temperature crystal-

line structure, ferrite, is stabilized and the steel remains in the ferritic condition at all tempera-

tures. Hence the name, ferritic stainless steel is applied to this alloy base.

5.4 AUSTENITIC STAINLESS STEELS

Austenitic Stainless Steels are designated by a series of 300 numbers according to the Ameri-

can Iron & Steel Institute (AISI). Nominal compositions of some of the more important types

are shown in Figure 7. About 80% of the stainless steel welded is of the austenitic type.

AISI No. Chromium % Nickel % Molybdenum % Columbium %

301 17 7302 18 9304 19 10309 23 13310 25 20316 17 12 2.5317 19 13 3.5347 18 11 1

MOST COMMON TYPES OF AUSTENITIC STAINLESS STEELS

FIGURE 7

5.4.1 Carbide Precipitation - Many of the austenitic stainless steels are subject to the

phenomenon of carbide precipitation. At elevated temperatures in the range of 800-1600°F,

the carbon content in excess of 0.02% migrates to the grain boundaries of the austenitic

structure where it reacts with chromium to form chromium carbide. If the chromium is tied up

with the carbon, it is not available for corrosion resistance. Thus, when the steel with carbide

precipitation is exposed to a corrosive environment, intergranular corrosion results, allowing

the grain boundaries to be eaten away. Figure 8 shows how intergranular corrosion may take

place in a tank holding a corrosive liquid. Notice that the corrosion takes place only in the heat

affected zone on the inside where the corrosive media is located, and there is no evidence of

failure on the outside.

5.4.1.1 Carbide precipitation has no other effect on the steel, however, other than loss of

corrosion resistance in the heat affected zone. During welding, the heat-affected zones along

the sides of the weld in austenitic stainless steel are exposed to the temperatures that cause

carbide precipitation.


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LESSON V

5.4.1.2 If the weldment is to be used in corrosive service, the carbide precipitation and

resultant intergranular corrosion must be eliminated. Three dependable methods of controlling

this problem are defined below:

a. Carbide precipitation is a function of the carbon content. Keeping the carbon content

as low as possible in the steel (0.04% maximum) and welding it with low carbon elec-

trodes is one solution.

b. If the carbon of the steel and weld metal are tied up by an element that has a stronger

affinity for carbon than does chromium, carbide precipitation cannot occur. Columbium

and titanium are alloys that have a stronger affinity for carbon. Steels with columbium or

titanium, and covered electrodes with columbium present, are made for this purpose.

c. Another method, although not as practical, is to heat the finished weldment to at least

1850°F allowing all of the precipitated carbides to go back into solution. The weldment

is then rapidly cooled and quenched so that it passes through the critical temperature

(1200°F) very quickly, allowing little or no carbides to reform. However, stainless steel

weldments heated to such high temperatures would be subject to warping, sagging and

other loss of dimension as well as being covered with heavy scale.

5.4.2 Ferrite in Austenitic Stainless Steel - Stainless weld metal that is fully austenitic is

non-magnetic and has a relatively large grain structure. This results in the weld being crack-

sensitive. By controlling the balance of the alloying elements in the electrode, small amounts of

another phase, ferrite, can be introduced in the weld metal. The ferrite phase causes the

austenitic grains to be much finer and the weld becomes more crack-resistant.

5.4.2.1 Certain alloying elements used in stainless steels and weld metals behave as

austenite stabilizers and others as ferrite stabilizers. Among the austenite stabilizers are

nickel, carbon, manganese and nitrogen. The ferrite stabilizers are chromium, silicon, molyb-

denum and columbium. It is the balance between the two types of alloying elements that

controls the quantity of ferrite in the weld metal.

INSIDE OFTANK

HEATAFFECTED

ZONES

WELDMETAL

INTERGRANULAR CORROSION

FIGURE 8


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Filler Metals


LESSON V

5.4.2.2 The amount of ferrite in austenitic stainless steel weld metal may be measured by

magnetic devices because the ferrite is magnetic. A small amount of ferrite in austenitic

stainless weld metal is good, because it prevents weld cracking. If the weldment is to be in

very low temperature service, however, large amounts of ferrite should be avoided because

ferrite is not tough at low temperatures. Also, if the weldment is to be used in high temperature

(higher than 1000°F) service, the ferrite should be maintained at low levels because the ferrite

becomes brittle at those temperatures.

5.5 CALCULATION OF FERRITE CONTENT INSTAINLESS STEEL

Several simple, yet accurate, methods have been developed for determining the balance

between the austenite and ferrite forming elements in iron. When the chemical composition of

the weld metal is known, the Schaeffler or WRC-1992 diagrams can be used. See Figures 9

and 10.

5.5.0.1 The purpose of these diagrams is to calculate the nickel and chromium equivalent of

the weld metal in question and plot the point on the appropriate diagram. The nickel equiva-

lent is the sum of the nickel content and all other austenite formers, multiplied by coefficients

representing their austenite forming effect as compared to that of nickel. The chromium

equivalent is calculated in the same manner. In both diagrams, the nickel equivalent is the

vertical axis, and the chromium equivalent is the horizontal axis. The WRC-1992 diagram has

an advantage since it also takes the nitrogen content into consideration. Nitrogen is a power-

ful austenite forming element. If the nitrogen content is not known, we assume 0.06% for

GTAW and SMAW electrodes and, 0.08% for GMAW and FCAW filler metals.

5.5.0.2 When chemical composition is not available, two common instruments can also be

used to determine ferrite content. Since ferrite at room temperature is magnetic and austenite

is not, a relationship between magnetic response and ferrite content can be established. The

more magnetic response to the instrument, the more ferrite present in the metal. The two

commercially available instruments that use this principal to measure ferrite content are the

Magne gage and the Severn gage. The Magne gage is a laboratory instrument, while the

Severn gage is a pocket-size instrument designed for on-site readings.

5.5.0.3 In the past, ferrite was expressed as a volume percent of the metal. However,

because of non-standard calibration, conflicting and inaccurate results often occurred. To

eliminate this problem, the ferrite volume percent was changed to a standardized expression

known as the ferrite number (FN) and has been adopted by the Welding Research Council

(WRC), the American Welding Society (AWS), and other agencies. Ferrite numbers (FN) are


Welding












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Filler Metals


LESSON V

the same as the volume percent numbers in the range of 0-7%. At higher contents, FN values

become increasingly higher than the previous percent ferrite values. The DeLong diagram

shows this comparison.

SHAEFFLER CONSTITUTION DIAGRAM FOR STAINLESS STEEL WELD METAL

FIGURE 9

WRC-1992 DIAGRAM FOR STAINLESS STEEL WELD DATA

FIGURE 10


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LESSON V

5.6 SPECIAL FERRITE REQUIREMENT IN STAINLESSSTEEL ELECTRODE

In order to meet the AWS classification of a stainless steel electrode, a specific chemical

range must be followed by the electrode manufacturers. Since ferrite content is mainly con-

trolled by chemical composition, the ferrite content will also fall into certain ranges depending

on the particular electrode in question. However, some users of stainless steel require the

ferrite content be above or below the normal ranges as found in typical chemical analyses. An

example of this is the SMAW 316 electrode. Normally, a 316 stick electrode has a FN in the 0-

2 range, but a specially formulated 316 stick electrode could have a minimum of 5 FN, if

needed. Since these electrodes require special chemical formulations, they must be ordered

on a special request basis from most manufacturers.

5.7 MARTENSITIC STAINLESS STEEL

Martensitic stainless steels fall into the 400 number series according to the American Iron and

Steel Institute. They are magnetic and contain from 11.5% to 18% chromium. As previously

noted, they get the name martensite because of the crystalline structure of the steel at room

temperature. With a lower alloy content than the austenitic steels, they are lower in cost than

the austenitic types. They have adequate corrosion resistance in many environments because

they form the characteristic chromium oxide surface film. They also have a high hardenability

characteristic.

5.7.0.1 Other chromium bearing heat resistant steels that have only 4% to 10% chromium

(not a true stainless steel by the 11.5% minimum chrome requirement) have similar

hardenability characteristics. These steels are designated by the 500 series numbers accord-

ing to the American Iron and Steel Institute and from a welding standpoint, may be considered

in the same grouping as the martensitic stainless steels. Nominal compositions of these types

are shown in Figure 11.

5.7.0.2 These steels are frequently in a hard-

ened state meaning they have low ductility. If

heat is applied suddenly, as in arc welding, to a

localized area and it then is allowed to cool

suddenly, cracking may occur. The heated area

contracts on cooling and the lack of ductility in

the parent metal prevents it from following along.

This type of cracking can be prevented by pre-

heating the steel, since preheating lowers the thermal difference between the weld area and

AISI No.Carbon

403 0.15 11.5 - 13410 0.15 11.5 - 13.5501 0.10 min 4 - 6 0.40 - 0.65502 0.10 4 - 6 0.40 - 0.65

* Maximum unless otherwise noted.

NOMINAL COMPOSITION-MARTENSITIC STAINLESSSTEELS AND CHROMIUM HEAT RESISTANT STEELS

FIGURE 11


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Filler Metals

%* %* %*

Molybdenum

Chromium


LESSON V

the base metal. This allows the weld area to cool more slowly and as a result, the steel in the

heat affected zone will not be hardened as severely.

5.7.0.3 The preheating temperature used is in the range of 350°F to 500°F and should be

maintained during the entire welding operation. Upon completion of welding, the weldment

should be cooled slowly, preferably furnace cooled, allowing gradual temperature change.

5.7.0.4 The mechanical properties of martensitic stainless steels are affected by welding

since they harden intensely, even on relatively slow cooling from high temperatures. The weld

deposit and the steel that surrounds the weld deposit is hard and brittle. Heat treatment of the

weldment is necessary to improve these physical properties.

5.7.0.5 If preheating or postweld heat treatment is not practical, it may be necessary to use

a higher alloy austenitic stainless steel electrode (such as 309) that deposits tough, ductile

weld metal without cracking. This solution would depend on the required properties of the

weldment and is not recommended in all cases. Martensitic stainless steels make up about

15% of the stainless steels that are welded.

5.8 FERRITIC STAINLESS STEELS

Ferritic stainless steels are straight chrome alloys in the AISI 400 series. They are magnetic

and have varying ranges of chromium content as shown in Figure 12.

5.8.0.1 All ferritic stainless steels have the room temperature crystal structure of ferrite

stabilized to all temperatures. The higher chromium content provides good resistance to high

temperature scaling. For this reason, the ferritic stainless steels are used to make heat treat-

ing containers, jigs, and fixtures.

5.8.0.2 Welding the ferritic high chromium

stainless steels, however, is difficult. The steels

have rapid rates of grain growth at temperatures

over 1700°F. The large grains absorb the

smaller grains and grow larger. The resultant

coarse grain structures are very crack sensitive.

Grain growth is a time and temperature function.

To keep the time of high welding temperature as

short as possible, these steels should be mildly preheated to about 300°F, welded with small

diameter electrodes and with the lowest possible welding current, thereby limiting the heat

input. About 5% of the stainless steels welded are of the ferritic category.

AISI No. Carbon %* Chromium %* Other %*

405 0.08 11.5 - 14.5 Aluminum0.10 - 0.30

430 0.12 16.0 - 18.0 --

446 0.20 23.0 - 27.0 Nitrogen0.25

* Maximum unless otherwise noted.NOMINAL COMPOSITION-FERRITIC STAINLESS STEELS

FIGURE 12


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LESSON V

5.9 DUPLEX STAINLESS STEELS

Duplex means "two". Duplex stainless steels consist of the two "building stones" (microstruc-

ture phases) ferrite and austenite and are often termed ferritic-austenitic stainless steels.

Typically, duplex stainless steels have a microstructure consisting of approximately 50% ferrite

and 50% austenite.

5.9.0.1 In simple terms, the ferrite could be said to give high strength and some resistance

to stress corrosion cracking, the austenite provides good toughness, and the two phases in

combination give the duplex steels their attractive corrosion resistance.

5.9.0.2 The most important alloying elements of duplex stainless steels are Cr, Ni, Mo and

N. These elements largely govern the properties of the steels. Some grades also contain

additions of copper (Cu) or tungsten (W).

5.9.0.3 A wide range of different versions of duplex stainless steel is currently available

on the market. At present, the 22% chromium (Cr), 5% nickel (Ni), 3% molybdenum (Mo),

0.15% nitrogen (N) grade (commonly called 2205) is the most common type of duplex stain-

less steel and is used in a wide range of applications. Higher alloyed duplex steels, the so-

called super duplex stainless steels, have also been introduced into the market. The 25%

chromium (Cr), 7% nickel (Ni), 4% molybdenum (Mo), 0.25% nitrogen (N) grade (commonly

called 2507) is one example of a modern high alloy super duplex stainless steel. These steels

are designed for use in demanding applications where even greater corrosion resistance or

higher strength is required.

5.10 ELECTRODE SELECTION

There are a great many AISI grades of stainless steel, and in many cases there is a matching

electrode for the AISI type. For instance, if both members of a weldment are AISI type 316, the

electrode to be used would be 316 also. It is not necessary to have a matching electrode for

every type of stainless steel, however, because some electrodes produce satisfactory welds

even though the chemical analysis of the steel may be slightly different.

5.10.0.1 Type 308 stainless steel electrodes may be used for welding AISI 201 and 202 that

have a lower nickel content and a high manganese content. Type 308 electrodes may also be

used to weld types 301, 302, 304, 305 and of course, 308 itself. Even though their chromium-

nickel contents vary slightly, all of these steel types may be considered as one family of alloys.

The chart in Figure 13 shows the proper Arcaloy electrode to be used for the various types of

AISI steels.


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Filler Metals


LESSON V

Arcaloy Electrodes to Weld AISI SteelsChemical Analyses of Stainless Steels, percent*

AISI** Other Weld withType Number Carbon Manganese Silicon Chromium Nickel Elements Arcaloy Type

Austenitic201 0.15 5.5/7.5 1.00 16.00/18.00 3.50/5.50 N 0.25 Max. 308/308 ELC202 0.15 7.5/10.0 1.00 17.00/19.00 3.50/5.50 N 0.25 Max. 308/308 ELC301 0.15 2.00 1.00 16.00/18.00 6.00/8.00 --- 308/308 ELC302 0.15 2.00 1.00 17.00/19.00 8.00/10.00 --- 308/308 ELC302B 0.15 2.00 2.00/3.00 17.00/19.00 8.00/10.00 --- 308/308 ELC303 0.15 2.00 1.00 17.00/19.00 8.00/10.00 S 0.15 Min.*** 312303Se 0.15 2.00 1.00 17.00/19.00 8.00/10.00 Se 0.15 Min. 312304 0.08 2.00 1.00 18.00/20.00 8.00/12.00 --- 308/308 ELC304L 0.03 2.00 1.00 18.00/20.00 8.00/12.00 --- 308 ELC305 0.12 2.00 1.00 17.00/19.00 10.00/13.00 --- 308/308 ELC308 0.08 2.00 1.00 19.00/21.00 10.00/12.00 --- 308/308 ELC309 0.2 2.00 1.00 22.00/24.00 12.00/15.00 --- 309309S 0.08 2.00 1.00 22.00/24.00 12.00/15.00 --- 309310 0.25 2.00 1.50 24.00/26.00 19.00/22.00 --- 310310S 0.08 2.00 1.50 24.00/26.00 19.00/22.00 --- 310314 0.25 2.00 1.50/3.00 23.00/26.00 19.00/22.00 --- 310/312316 0.08 2.00 1.00 16.00/18.00 10.00/14.00 Mo 2.00/3.00 316/316 ELC316L 0.03 2.00 1.00 16.00/18.00 10.00/14.00 Mo 2.00/3.00 316 ELC317 0.08 2.00 1.00 18.00/20.00 11.00/15.00 Mo 3.00/4.00 317/317 ELC321 0.08 2.00 1.00 17.00/19.00 9.00/12.00 Ti 5 x C Min. 308 ELC/347347 0.08 2.00 1.00 17.00/19.00 9.00/13.00 Cb + Ta 10 x C Min. 308 ELC/347348 0.08 2.00 1.00 17.00/19.00 9.00/13.00 Cb + Ta 10 x C Min. 308 ELC/347

Ta 0.10 Max.20Cb-3 0.06 2.00 1.00 19.00/21.00 32.50/35.00 Cb + Ta 8 x C min.

1.00% Max.

Martensitic403 0.15 1.00 0.50 11.50/13.00 --- --- 309410 0.15 1.00 1.00 11.50/13.50 --- --- 309414 0.15 1.00 1.00 11.50/13.50 1.25/2.50 --- 309/410416 0.15 1.25 1.00 12.00/14.00 --- S 0.15 Min.*** 312/410416Se 0.15 1.25 1.00 12.00/14.00 --- Se 0.15 Min. 312/410420 Over 0.15 1.00 1.00 12.00/14.00 --- --- 309/410431 0.2 1.00 1.00 15.00/17.00 1.25/2.50 --- 309/430CA6NM 0.06 1.00 1.00 11.50/14.00 3.5/4.5 Mo 0.4-1.0 410NiMo

Ferritic405 0.08 1.00 1.00 11.50/14.50 --- Al 0.10/0.30 309/410430 0.12 1.00 1.00 14.00/18.00 --- --- 309/430430F 0.12 1.25 1.00 14.00/18.00 --- S 0.15 Min.*** 312/430430Se 0.12 1.25 1.00 14.00/18.00 --- Se 0.15 Min. 312/430442 0.2 1.00 1.00 18.00/23.00 --- --- 309/310446 0.2 1.50 1.00 23.00/27.00 --- N 0.25 Max. 309/310

* Single Values are Maximums Except as Noted. If service allows** According to AISI Steel Products Manual, Stainless and Heat Resisting Steels. Not regarded as weldable*** Molybdenum Content of up to 0.60% Permissible and is optional with the Producer.

STAINLESS STEEL SELECTION CHART

FIGURE 13

320LR


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LESSON V

5.11 WELDING DISSIMILAR STEELS

Stainless steels are expensive and the higher the alloy content of the steel, the higher the cost.

The most efficient design of a structure calls for the use of the higher alloy steels only where

they are needed. Such a design may call for several different steels to be used. As mentioned

above, there is no problem of electrode selection when welding stainless steels or any steel to

a steel of the same type. Simply match the electrode to the steels. When a change from one

type of steel to another (called a transition weld) is made, care must be given to the selection

of the electrode used.

5.11.0.1 There are two general conditions and rules for electrode selection to weld dissimilar

steels.

a. When the steels are similar metallurgically but dissimilar chemically, match the

electrode to the lower chemical composition or less expensive steel. For example, type 310

steel (25% chromium, 20% nickel) is sometimes welded to type 304 steel (19% chromium,

10% nickel). Both types are austenitic. Type 304 steel, which is welded with 308 electrodes,

is less expensive, so that weld would be made with type 308 electrodes rather than type 310

electrodes.

b. When the steels to be jointed are different metallurgically and chemically, the

electrode is selected to provide a tough, crack resistant weld between the two steels. For

example, 304 stainless steel is frequently welded to mild structural steel. Corrosion resistance

cannot be part of the problem because mild steel is on one side of the joint with practically no

corrosion resistance compared to the stainless steel. If this weld is made with mild steel

electrodes to match the mild steel side of joint, the weld metal would be enriched by the wash-

in of chromium and nickel from the stainless side. This intermediate chrome-nickel is usually

hard and crack sensitive. If the weld is made with type 308 electrodes to match the stainless

steel side of the joint, the chromium and nickel contents of the weldment are diluted by the mild

steel side of the joint to an intermediate level that would again probably be hard and crack

sensitive. When welding mild steel to stainless steel, a proportion of 18% chromium and 8%

nickel is desirable in the weld deposit to produce sound welds, with 17% chromium and 7%

nickel being the minimum allowable amounts.

5.11.0.2 The following examples in Figure 14 show the results of making a transition weld of

mild steel to 304 stainless steel with three different electrodes.


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LESSON V

5.11.0.3 Normally the most severe dilution of the weld metal by the base metal is 40%. Thus,

the weld metal in the joint is comprised of 60% from the electrode and 40% from the base

metal as shown in Figure 14. In the case of butt joints between dissimilar steels, half of the

dilution comes from each side of the joint, or 20% from each base metal.

5.11.0.4 Many times, type 310 and 312 electrodes are used erroneously for welding stain-

less to mild or low alloy steel. In many cases, not only can more dependable welds be made

with 309 electrodes, but appreciable savings can be achieved because of their lower cost.

308 ELECTRODE

ELECTRODE X 60% 304 X 20% MILD WELDSTEEL X 20% METAL

CHROMIUM 19.5 11.7 18.0 3.6 0 0 15.3NICKEL 9.5 5.7 8.0 1.6 0 0 7.3

The composition of 15.3% chromium and 7.3% nickel does not meet the minimum 17-7%proportion. The weld metal will be mostly martensitic with a very small amount of ferrite.This structure is quite brittle.

310 ELECTRODE


CHROMIUM 26.0 15.6 18.0 3.6 0 0 19.2NICKEL 21.0 12.6 8.0 1.6 0 0 14.2

The composition of 19.2% chromium and 14.2% nickel is not near the 18/8 proportion.The weld metal would be fully austenitic and crack sensitive.

309 ELECTRODE


CHROMIUM 23.0 13.8 18.0 3.6 0 0 17.4NICKEL 13.0 7.8 8.0 1.6 0 0 9.4

The composition of 17.4% chromium and 9.4% nickel is close to the 18/8 proportion. Theweld metal will be austenitic with some ferrite and a small amount of martensite to keepthe weld metal from being tough and crack resistant. 309 is the best choice.

60%

20%

304 MILDSTEEL

20%

ELECTRODE SELECTION - 304 STAINLESS TO MILD STEEL

FIGURE 14

ELECTRODE


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Filler Metals


LESSON V

5.11.0.5 Another common use of stainless steel filler metals is the overlaying or cladding of

less expensive steels with a layer of stainless. Mild steel tanks designed to hold corrosive

liquids may be lined with stainless steel in this manner. Usually, continuous bare or flux cored

electrodes are used with an automated welding setup. Current and penetration must be

controlled closely to limit dilution with the base metal. Sometimes it is necessary to deposit

more than one layer to assure the correct analysis of the deposit.

5.11.0.6 The welding of stainless clad plate (produced by some steel mills) should also be

mentioned. Thicker sections may be welded with both mild steel and stainless electrodes, and

thinner sections may be welded only with stainless electrodes. Joint preparation, welding

procedure and electrode selection will vary with the thickness and type of clad plate being

welded. Welding of clad plate is a specialized area of dissimilar metal welding and beyond

the scope of this course.

5.12 STAINLESS STEEL ELECTRODES AND FILLER METALS

There are several different forms of stainless steel electrodes: covered, continuous solid bare,

continuous flux cored and cut length bare welding rods.

5.12.1 Covered Stainless Electrodes - Arcaloy covered stainless steel electrodes are

classified according to the American Welding Society Filler Metal Specification A-5.4-92. As

defined by that specification, the electrodes are classified by weld metal composition and type

of welding current. For example, the AWS designation E308-15 means electrode (E), AISI

type 308 steel (20% chrome, 10% nickel) and direct current electrode positive (-15). If the

classification reference were E308-16, it would indicate an electrode (E), AISI type 308 steel

(308) and AC-DC electrode positive operation (-16 & -17). Arcaloy lime coated electrodes

have the DC suffix -15, Arcaloy AC-DC electrodes have the suffix -16, and Arcaloy Plus elec-

trodes use the -17 suffix.

5.12.1.1 Arcaloy high alloy stainless steel covered electrodes are produced by extruding

carefully formulated and mixed coating material on a stainless steel core wire, thus ensuring

constant weld metal properties and composition.

5.12.1.2 Arcaloy stainless steel electrodes have been among the leaders in the stainless

electrode industry for many years. The strict purchase specifications for the core wire and the

covering materials, and the rigid quality control under which the Arcaloy electrodes are manu-

factured, have resulted in this position of leadership.


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LESSON V

5.12.2 Arcaloy lime coated electrodes were among the earliest stainless steel elec-

trodes developed in the United States. Designed for welding with direct current, reverse

polarity only, the coating contains considerable amounts of limestone and fluorspar producing

a fast freezing slag that facilitates welding in the vertical and overhead positions. The weld

bead is slightly convex and moderately rippled. (See Figure 15).

5.12.2.1 Characterized by a strong globular arc, a moderate amount of spatter and slag

removal that is somewhat difficult, the lime type is not the most popular with the welding opera-

tors. However, it is the easiest to use stainless electrode for out-of-position welding. Also, the

convex bead can provide the necessary margin of safety in highly stressed joints in many

cases.

5.12.3 Arcaloy AC-DC Titania coated electrodes were the first such electrodes to

receive wide acceptance in this country. Designed to operate on alternating current as well as

direct current, the coating contains dominant amounts of rutile (titania), medium amounts of

limestone, and limited amounts of fluorspar. By far, the AC/DC type is the most popular of the

coated stainless electrodes. Welders like to use it because of the smoother arc action, low

amount of fine spatter and easy slag removal. Also, the bead is relatively flat, finely rippled and

has good side-wall fusion (See Figure 15). Although used in all positions, vertical and over-

head welding requires slightly more operator skill than with the lime types because the slag

does not freeze as quickly.

5.12.4 Arcaloy "Plus" electrodes display characteristics not found in the conventional

lime and AC-DC Titania coatings. Designed to operate on DCEP or AC, this coating is

specially formulated to operate on a broad range of current settings, and most significantly,

these electrodes perform their best at high heat inputs where conventional AC-DC electrodes

tend to break down.

5.12.4.1 When operating at high currents, Arcaloy Plus electrodes deposit weld metal at

exceptional speeds with a smooth spray transfer. The bead profile is finely rippled, concave,

and evenly feathered (See Figure 15). Spatter is minimal. The molten slag does not edge

into the weld puddle, thereby assuring easy visibility of the arc transfer.

5.12.4.2 Arcaloy Plus electrodes were developed for applications on dairy and food pro-

cessing equipment and chemical containers, to name a few, where the weld radius must be

smooth and concave to prevent particle entrapment. When welding in the flat and horizontal

fillet positions, the concave deposit and absence of surface irregularities make it ideal for

applications where cosmetic appearance, speed, and final finishing are factors.


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LESSON V

5.12.4.3 The weld metal properties are similar for each of the three coating types: lime, AC-

DC and AC-DC Plus.

5.13 ARCALOY COVERED ELECTRODE PROPERTIESAND APPLICATIONS

5.13.1 Arcaloy 308L (AWS E308/308L-15 & -16), Arcaloy 308L Plus (AWS E308/308L-17) - This extra low carbon composition is intended to weld Type 304L steels to prevent car-

bide participation. It can also be used to weld Types 321 and 347 steels. Typical chemical

composition of weld metal is:

Carbon 0.03% Chromium 19.1%

Nickel 9.7% Manganese 1.6%

Silicon 0.4% Ferrite No. 8

5.13.2 Arcaloy 309L (AWS E309L-15 & -16), Arcaloy 309L Plus (AWS E309/309L-17)

- The low carbon content of Arcaloy 309 L weld metal makes it useful to weld low carbon

overlay on carbon or low alloy steel to control carbide precipitation in the overlay. The chemi-

cal composition of the weld metal is the same as that of Arcaloy 309 except that the carbon

content is 0.04% and the typical ferrite no. is 8.

5.13.3 Arcaloy 309 Cb (AWS 309Cb-15 & -16) - The addition of columbium to Type 309

weld metal improves its high temperature performance. It is also useful in welding Types 321

and 347 clad steels. The weld metal composition is the same as Type 309, except that 0.80%

columbium is added and the ferrite no. is 8.

(-15) (-16) (-17)LIME AC-DC PLUS

CONVEX FLAT CONCAVEMODERATE RIPPLE LOW RIPPLE MININUM RIPPLE

WELD BEAD SHAPE ARCALOY COATED ELECTRODES

FIGURE 15


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TECHNOLOGY


LESSON VICARBON AND

LOW ALLOY STEELFILLER METALS

FOR THE GMAW, GTAW ANDSAW WELDING PROCESSES


©COPYRIGHT 2000 ESAB WELDING & CUTTING PRODUCTS


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LESSON VI

TABLE OF CONTENTSLESSON VI

CARBON & LOW ALLOY STEEL FILLERMETALS FOR THE GMAW, GTAW, AND SAW

WELDING PROCESSES

6.1 Introduction ............................................................................................. 1

6.2 Manufacturing ......................................................................................... 2

6.3 Wire Selection for Gas Shielded Arc Welding ........................................ 3

6.4 AWS Specification A5.18-93

Carbon Steel Filler Metals for Gas Shielded Arc Welding ....................... 6

6.5 Individual Filler Metal Characteristics ..................................................... 8

6.5.1 ER70S-2 ................................................................................................. 8

6.5.2 ER70S-3 ................................................................................................. 8

6.5.3 ER70S-4 ................................................................................................. 8

6.5.4 ER70S-5 ................................................................................................. 8

6.5.6 ER70S-6 ................................................................................................. 8

6.5.6 ER70S-7 ................................................................................................. 9

6.5.7 ER70S-G ................................................................................................ 9

6.6 ESAB Bare Solid Carbon Steel Wires .................................................... 9

6.6.1 SPOOLARC 65 ....................................................................................... 9

6.6.2 SPOOLARC 29S .................................................................................... 10

6.6.3 SPOOLARC 85 ....................................................................................... 10

6.6.4 SPOOLARC 86 ...................................................................................... 11

6.6.5 SPOOLARC 87HP .................................................................................. 11

6.7 AWS Specification AWS A5.28-96

Low Alloy Steel Filler Metals for Gas Shielded Arc Welding ................... 12

6.7.1 The Chromium-Molybdenum Types........................................................ 12

6.7.2 The Nickel Alloy Types ............................................................................ 13


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6.7.3 The Manganese-Molybdenum Types ........................................................ 14

6.7.4 SPOOLARC 83 ....................................................................................... 15

6.7.5 SPOOLARC Hi-84 .................................................................................. 15

6.7.6 All Other Low Alloy Types ......................................................................... 16

6.7.7 SPOOLARC 95 and 120 ......................................................................... 17

6.8 Wires and Fluxes for Submerged Arc Welding of Carbon Steels ........... 18

6.8.1 Equipment............................................................................................... 18

6.8.2 Welding Filler Metals .............................................................................. 19

6.8.3 Fluxes for Carbon Steel Electrodes ........................................................ 19


Carbon Steel Electrodes and Fluxes for Submerged Arc Welding ......... 21

6.10 ESAB Wires and Fluxes for Carbon Steel Submerged Arc Welding ...... 23

6.10.1 SPOOLARC 81 ....................................................................................... 23

6.10.2 SPOOLARC 29S .................................................................................... 23

6.10.3 SPOOLARC 80 ....................................................................................... 24

6.10.4 UNIONMELT 231 .................................................................................... 24

6.10.5 UNIONMELT 429 .................................................................................... 25

6.10.6 UNIONMELT 282 .................................................................................... 25

6.10.7 UNIONMELT 50 ...................................................................................... 26

6.10.8 UNIONMELT 80 ...................................................................................... 26

6.11 Electrodes and Fluxes for Submerged Arc Welding of the

Low Alloy Steels ...................................................................................... 27

6.11.1 Electrodes and Fluxes for Welding the Alloys......................................... 27


Low Alloy Steel Electrodes and Fluxes for Submerged Arc Welding ...... 28

6.12.1 Composition Requirements for Solid Low Alloy Electrodes .................... 29

6.13 Spoolarc Low Alloy Wires for Submerged Arc Welding .......................... 31

TABLE OF CONTENTSLESSON VI - Con't.


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6.13.1 Manganese-Molybdenum Wires .............................................................. 31

6.13.2 Chromium-Molybdenum Wires ................................................................. 31

6.13.3 Nickel Wire .............................................................................................. 31

6.13.4 High Strength Wires................................................................................. 31

6.13.5 Special Purpose Wires ............................................................................ 31

6.14 Unionmelt Fluxes for Welding Low Alloy Steels ...................................... 32

6.14.1 Unionmelt 429......................................................................................... 32

6.14.2 Unionmelt 439......................................................................................... 32

6.14.3 Unionmelt 656......................................................................................... 32

6.15 Alloy Shield Composite Electrodes for Submerged Arc

Welding of the Low Alloy Steels .............................................................. 32

6.15.1 Alloy Shield B1S ..................................................................................... 32

6.15.2 Alloy Shield B2S ..................................................................................... 33

6.15.3 Alloy Shield B3S ..................................................................................... 34

6.15.4 Alloy Shield Ni1S .................................................................................... 34

6.15.5 Alloy Shield Ni2S .................................................................................... 35

6.15.6 Alloy Shield M2S..................................................................................... 35

6.15.7 Alloy Shield M3S..................................................................................... 36

6.15.8 Alloy Shield WS ...................................................................................... 36

6.15.9 Alloy Shield F2S ..................................................................................... 37

6.15.10 Alloy Shield 420SB ................................................................................. 37

Appendix A Glossary of Terms ................................................................................... 39

TABLE OF CONTENTSLESSON VI - Con't.


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®COPYRIGHT 2000 THE ESAB GROUP, INC.

LESSON VI

CARBON AND LOW ALLOY STEEL FILLERMETALS FOR THE GMAW, GTAW AND SAW

WELDING PROCESSES

6.1 INTRODUCTION

6.1.0.1 During the early part of the 20th century, some welding was done using bare steel

wires or rods. The weld quality was poor because of the oxides and nitrides found in the weld

metal. Even after the advent of the extruded coated electrode in 1927, automated welding

using bare wires (or lightly coated wires) continued to be used, despite the poor qualities of

the welds, because this method allowed more rapid deposition of the weld metal. Critical

welds, however, were made with coated electrodes.

6.1.0.2 The advantages of using an inert gas to shield the arc were known during the 20’s

and 30’s, but the inert gases, such as helium and argon, were too expensive to produce.

6.1.0.3 In 1935, submerged arc welding (then known as submerged melt welding) was

introduced and provided a method of producing quality welds at greater welding speeds than

were obtainable with coated electrodes.

6.1.0.4 During World War II, the aircraft industry needed a reliable process for welding

magnesium engine parts and as a result, gas tungsten arc welding (GTAW), using a bare filler

wire and a helium gas shield, was developed.

6.1.0.5 Economical methods of producing the inert gases were ultimately developed,

leading to the use of solid wire with a helium or argon gas shield in the 1940’s. This process

became known as metal inert gas (MIG) welding.

6.1.0.6 In the early 1950’s, it was realized that a more economical shielding gas, such as

carbon dioxide, could be used if the wire chemistry was adjusted to neutralize the oxidizing

effect of this gas. Since carbon dioxide (CO2) is not an inert gas, the name MIG welding

actually did not apply to this process since CO2 is a reactive gas. As a result, the AmericanWelding Society has standardized on the term GMAW (Gas Metal Arc Welding) to include the

inert gases, active gases, and gas mixtures as covered in Lesson II. In Europe, the term MIG

(Metal Inert Gas) welding still applies to the process if an inert gas or mixtures of inert and

active gases are used, and the term MAG (Metal Active Gas) is used if straight CO2 is em-ployed as the shielding gas.


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LESSON VI

6.1.0.7 Although carbon steel, low alloy steels, stainless steels, magnesium, copper, copper

alloys, titanium and other metals may be welded by one or all of the processes described

above, this Lesson will be confined to the filler metals for welding mild or carbon steels, and

low alloy high strength steels with the GMAW and GTAW processes.

6.2 MANUFACTURING

6.2.0.1 The manufacture of solid welding wires for GMAW or GTAW differs from the manu-

facture of coated or flux cored electrodes in that the deoxidizers and alloying elements that

contribute to the purity and mechanical properties of the weld metal, must be included in the

wire chemistry rather than in the flux. Therefore, the raw material must be ordered from the

supplier to exact specifications. When received, a sample from both ends of each coil of the

hot rolled rod is analyzed by the manufacturer to ensure that the “hot rod”, as it is called, meets

these specifications.

6.2.0.2 The hot rod is cleaned to remove mill scale or rust and drawn to an intermediate

diameter. At this stage, the wire has “work hardened” which necessitates that it be annealed

before it is copper plated, drawn down to final size, spooled and packaged.

6.2.0.3 Close quality checks must be made throughout the manufacturing process to insure

that the end product is a smooth finished, uniform diameter wire, that will feed easily through

the end user’s wire feeding equipment and welding gun. The wire is copper plated and/or

otherwise coated to retard oxidation or rusting of the wire, to decrease contact tip wear, and to

assure good electrical conductivity. The plating or coating must not flake off or leave a residue

that will clog the wire feed cable or the welding gun. If copper coated, the layer of copper must

be kept to a low level to minimize copper welding fumes and flaking.


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6.3 WIRE SELECTION FOR GAS SHIELDED ARC WELDING

6.3.0.1 When selecting the wire or filler metal for either the GMAW or GTAW process,

several things must be considered.

1. Mechanical Properties - The wire chosen must produce weld metal having approxi-

mately the same mechanical properties as the base metal whether it is carbon steel or

low alloy high tensile steel.

2. Shielding Gas - In Lesson II, we learned that the shielding gases used in GTAW of

carbon steel are pure argon or argon helium mixtures. In GMAW, shielding gases may

be pure CO2, or mixtures of argon, helium, CO2 and oxygen. The gas mixtures contain-

ing oxygen or CO2 will exhibit oxidizing characteristics which, if they combine withcarbon, will form carbon monoxide gas porosity in the weld metal.

a. The most common shielding gases used for welding mild and low alloy steels may

be classified in terms of their oxidizing effect as shown in Figure 1.

b. Each of the following variables should be considered when selecting the proper gas

for a specific job:

• MATERIAL TYPES • WELD METAL MECHANICAL

- Carbon, Stainless, Aluminum, etc. PROPERTIES

• MATERIAL CONDITION • JOB REQUIREMENT

- Rusty, Oily, Primed, etc. - Fit-Up

• TYPES OF METAL TRANSFER - Penetration

- Short Circuit, Spray, Pulse, etc. - Spatter Levels

OXIDATION POTENTIAL OF COMMONLY USED SHIELDING GASES

FIGURE 1

Pure Argon or 98% Argon 75% ArgonArgon - Helium 2% O2 25% CO2 Pure CO2

Mixtures

Process GTAW GMAW GMAW GMAW

Degree of Non- Slightly More MostOxidation Oxidizing Oxidizing Oxidizing Oxidizing


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LESSON VI

3. Wire Chemistry - In order to provide specific characteristics, it may be necessary to

have a filler metal that matches the base plate chemistry. The most common examples

are requirements to weld 1-1/4 Cr - 1/2 Mo steel with ER80S-B2(L) or 2-1/4 Cr - 1 Mo

steel with ER90S-B3(L) providing matching high temperature strength and scaling

resistance.

a. To minimize the oxidizing effect of the various shielding gases, elements that are

called deoxidizers are included in the wire in varying amounts. These deoxidizers,

usually silicon and manganese, and to a lesser extent titanium, aluminum, and zirco-

nium, will combine with the oxygen in preference to reacting with the carbon and will

form very small amounts of harmless glass-like slag islands on the weld surface.

b. In the case of GTAW of steels where inert gases such as argon or argon-helium

mixtures are used, there will be little or no loss of the deoxidizers.

c. In GMAW, where shielding gases of different mixtures are used and welds of the

highest quality are required, the filler wire must be selected to allow for the degree of

oxidation of the shielding gas. When welding carbon or low alloy steels with a 98%

argon - 2% oxygen mixture, wires containing low amounts of manganese and silicon

may be used. If welding carbon or low alloy steels with a 75% argon - 25% CO2 shield-ing gas, wires with a higher amount of deoxidizers may be necessary to maintain the

proper manganese and silicon content in the weld metal. When welding with straight

CO2 as a shielding gas, wires with an even greater amount of deoxidizers may benecessary.

4. Base Metal - The type of steel in the base metal will influence the type of wire selected.

Rimmed steel (see Lesson I), which involve the least oxidation during manufacture, will

require that the filler wire contain a higher level of deoxidizers than semi-killed steel that

is partially deoxidized. Killed steels that are fully deoxidized when manufactured may

be welded with wires with a lower deoxidizer content.

5. Rust and Mill Scale - which are actually iron oxide (FeO) are a further source of oxy-

gen that is detrimental to the weld metal unless a wire containing sufficient deoxidizers

is selected. Cold rolled steel, that is devoid of mill scale and is reasonably rust free,

may be welded with a wire having lower amounts of silicon and manganese. Hot rolled

steel, that is characterized by having some amount of mill scale on the surface, requires

a wire containing greater amounts of deoxidizers to produce sound welds.


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LESSON VI

6. Bead Geometry - Bead geometry (or bead shape) is influenced by both the amount ofdeoxidizers in the wire and by the specific selection of shielding gas. Increasing the

silicon and manganese content of the wire will produce flatter beads and better side

wall fusion (wetability) because the puddle is more fluid. See Figure 2.

a. The choice of shielding gas like-

wise influences bead shape. CO2

produces more spatter and a higher

crown or more convex bead.

Argon-CO2 and argon-O2 gas mixturesprovide smoother metal transfer, less

spatter, and better bead appearance.

7. Welding Current - When welding athigh current for greater weld metal deposition, the weld puddle becomes larger, mean-

ing that more of the base metal has been melted and will stay molten for a longer pe-

riod, allowing more time for oxidation and resultant porosity to take place. Also, high

currents produce a greater amount of heat in the arc area and will cause greater

amounts of an oxidizing shielding gas to be dissociated, thereby releasing more oxy-

gen in the area of the molten pool. For these reasons, a wire with higher levels of

deoxidizing elements should be selected for high current operation.

6.3.0.2 To summarize, the above 7 factors must be properly considered in order to produce

top quality welds. The economics of your decision should never compromise the need to

deposit the highest weld metal integrity possible. The result of your decision will only lead to

most cost effective choice of welding materials. The following are economic considerations:

1. The cost of the wire increases with the percentage of deoxidizers and alloying elements

such as silicon, manganese, chromium, molybdenum, nickel, etc. in the welding wire.

2. The cost of pure carbon dioxide is approximately one-fourth that of argon and

argon-CO2 or argon-O2 mixtures.

3. The deposition efficiency of solid wires is very high, but it varies with the shielding gas

and welding current being used. Figure 3 shows the average efficiency when using the

more common shielding gases. The differences in efficiency are due to spatter loss,

and are proportional to the amount of argon in the gas mixture. CO2 produces moreweld spatter and therefore a lower deposition efficiency.

SILICON-MANGANESE EFFECT ON BEAD SHAPEFigure 2

LOW SILICON-MANGANESECONTENT

HIGH SILICON-MANGANESECONTENT


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LESSON VI

4. The deposition rate of solid wires is very high when compared to that of coated elec-

trodes, but is somewhat lower than the deposition rate of flux cored electrodes.

6.4 AWS SPECIFICATION A5.18-93

6.4.0.1 This AWS specification is entitled Specification for Carbon Steel Filler Metals forGas Shielded Arc Welding. It covers bare carbon steel solid wires for use with the GMAW

and GTAW processes. It differs from the AWS specifications in the previous lessons in that it

classifies the chemical composition of the wire rather than that of the weld metal. It does,

however, classify the mechanical properties of the weld metal in the as-welded condition using

the gas metal arc welding process.

6.4.0.2 The chemical composition requirements are based on the chemical analysis of the

as-manufactured wire or filler metal and include the elements in the coating or copper plating

applied by the manufacturer.

6.4.0.3 The letter-number designations

in this specification are shown in Figure 4.

For example, ER70S-3 indicates an

electrode or welding rod (ER) that will

produce weld metal of a minimum 70,000

psi tensile strength (70); is a solid bare

wire or welding rod (S); of a specific

chemical composition (3) as shown in

Figure 5. For a complete chemical

composition of these wires, see AWS A5.18-93.

ELECTRODE OR WELDING RODMIN. TENSILE STRENGTH X 1000 psi

E R X X S - X

CHEMICAL COMPOSITIONBARE SOLID ELECTRODE OR ROD

LETTER - NUMBER DESIGNATIONSCARBON AND LOW ALLOY STEEL WIRES

FIGURE 4

DEPOSITION EFFICIENCIES - GAS METAL ARC WELDINGCARBON AND LOW ALLOY STEEL WIRES

FIGURE 3

Shielding Gas Efficiency Range Average Efficiency

Pure CO2 88% - 95% 93%

75% Ar - 94% - 98% 96%25% CO2

98% Ar - 2% O2 97% - 98.5% 98%


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LESSON VI

MAJOR ALLOYING ELEMENTS - % BY WEIGHT

AWS CLASS CARBON MANGANESE SILICON TITANIUM ZIRCONIUM ALUMINUM

ER70S-2 0.07 0.90 - 1.40 0.40 - 0.70 0.05 - 0.15 0.02 - 0.12 0.05 - 0.15

ER70S-3 0.06 - 0.15 0.90 - 1.40 0.45 - 0.70 — — —

ER70S-4 0.07 - 0.15 1.00 - 1.50 0.65 - 0.85 — — —

ER70S-5 0.07 - 0.19 0.90 - 1.40 0.30 - 0.60 — — 0.50 - 0.90

ER70S-6 0.07 - 0.15 1.40 - 1.85 0.80 - 1.15 — — —

ER70S-7 0.07 - 0.15 1.50 - 2.00 0.50 - 0.80 — — —

ER70S-G NO CHEMICAL REQUIREMENTS

CHEMICAL COMPOSITION - CARBON STEEL BARE WIRESFIGURE 5

6.4.0.5 Tensile strength requirements of the weld metal produced by the filler metals in this

classification are shown in Figure 6.

Tensile Yield

Shielding Strength Strength Elongation

AWS Class Gas PSI PSI in 2" - % Min.

ER70S-2

ER70S-3

ER70S-4

ER70S-5 CO272,000 60,000 22

ER70S-6

ER70S-7

ER70S-G * 72,000 60,000 22

* As agreed upon between supplier and purchaser

WELD METAL TENSILE REQUIREMENTS

FIGURE 6

}

MinimumAWS Class Impact Properties

ER70S-2 20 ft-lb @ -20° F

ER70S-3 20 ft-lb @ 0° F

ER70S-4 Not Required

ER70S-5 Not Required

ER70S-6 20 ft-lb @ -20° F

ER70S-7 20 ft-lb @ -20° F

ER70S-G As agreed betweensupplier & purchaser

WELD METAL IMPACT PROPERTIES

FIGURE 7

6.4.0.6 Although Figure 6 shows CO2 as the shielding gas, the specification does not

restrict the use of argon-CO2 or

argon-mixtures. It states that a filler metal

classified with CO2 will also meet

specification requirements when used with

the above gas mixtures.

6.4.0.7 Impact properties, according to

the Charpy V-notch test as listed in the

specification, are shown in Figure 7.


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LESSON VI

6.5 INDIVIDUAL FILLER METAL CHARACTERISTICS

6.5.1 ER70S-2 - This classification covers filler metals that contain small amounts of

titanium, zirconium, and aluminum, in addition to the normal deoxidizing elements of manga-

nese and silicon. These wires are commonly referred to as “triple deoxidized wires”. They will

produce sound welds in all types of carbon or mild steels. They are especially suited for

welding carbon steels that are rusty or have mill scale on the surface. Weld integrity will vary

with the amount of oxides on the surface of the steel. They may be used with CO2, argon-CO2,

or argon-O2 shielding gas mixtures. They work well in the short-circuiting mode forout-of-position welding.

6.5.2 ER-70S-3 - Filler metals of this classification contain a relatively low percentage of

deoxidizing elements; however, they are one of the most widely used GMAW wires. They

produce welds of fair quality when used to weld rimmed steels (steels with high oxygen con-

tent) using argon-O2 or argon-CO2 as a shielding gas. The use of straight CO2 is not recom-mended when welding rimmed steels. Sound welds may be made when welding semi-killed

(low oxygen) and killed (fully deoxidized) steels using argon-O2, argon-CO2, or straight CO2.

6.5.2.1 Wires of this classification may be used for out-of-position welding in the

short-circuiting transfer mode using argon-CO2 or CO2 shielding gas.

6.5.2.2 When CO2 shielding gas is used, high welding currents should be avoided becausewelds produced may not meet the minimum tensile and yield strengths of this specification.

6.5.3 ER70S-4 - Containing slightly higher silicon and manganese contents than the

ER70S-3 type, these filler metals will produce weld metal of higher tensile strength. Primarily

used for CO2 shielding gas applications where a higher degree of deoxidization is necessary.

6.5.4 ER70S-5 - The filler metals in this classification contain aluminum as well as silicon

and manganese as deoxidizers. The addition of aluminum allows these wires to be used at

higher welding currents with CO2 as the shielding gas. Not used for out-of-positionshort-circuiting type transfer because of high puddle fluidity. Can be used for welding rusty or

dirty steels with a slight loss of weld quality.

6.5.5 ER70S-6 - Wires in this classification contain the highest combination of deoxidiz-

ers in the form of silicon and manganese. This allows them to be used for welding all types of

carbon steel, even rimmed steels, using CO2 as a shielding gas. They produce smooth, wellshaped beads, and are particularly well suited for welding sheet metal. This filler metal is also

useable for out-of-position welding with short-circuiting transfer. Moderately rusted or scaled


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LESSON VI

steels may be welded successfully with this wire. The weld quality depends on the degree of

surface impurities. This wire may be used for high current, high deposition welding using

argon mixed with 5-10% oxygen or carbon dioxide.

6.5.6 ER70S-7 - This wire is similar to the ER70S-3 classification, but it has a higher

manganese content which provides better wetting action and bead appearance. The tensile

and yield strengths are slightly higher, and welding speed may be increased compared to the

ER70S-3 type. This filler metal is usually recommended for use with argon-O2 shielding gas

mixtures, although argon-CO2 and straight CO2 may be used. The weld metal will be slightlyharder than that of the ER70S-3 types, but not as hard as an ER70S-6 deposit.

6.5.7 ER70S-G - This classification may be applied to solid filler metals that do not fall

into any of the preceding classes. It has no specific chemical composition or shielding gas

requirements, but must meet all other requirements of the AWS A5.18-93 specification.

6.6 ESAB BARE SOLID CARBON STEEL WIRES

6.6.1 Spoolarc 65 (AWS Class ER70S-2) - Spoolarc 65 is a cut length electrode avail-

able for a variety of tig and oxy-fuel gas welding applications. In addition to the standard

deoxidizers, ER70S-2 also contains additional cleaners such as aluminum, titanium, and

zirconium. This electrode is often used on out-of-position welding of pipe joints. The ends of

the 36" electrode can be flag tagged for identification purposes.

A. Typical Chemical Analysis of the Wire

Carbon 0.08% Phosphorus 0.011%

Manganese 1.00% Sulfur 0.009%

Silicon 0.40%B. Typical Mechanical Properties of the Weld Metal

As Welded Stress Relieved*





Charpy V-Notch Impacts

ft.-lbs. @-20°F 170 160

* 8 hrs. at 1150°F


Welding












Electrodes




Filler Metals


LESSON VI

6.6.2 Spoolarc 29S (AWS Class ER70S-3) - Spoolarc 29S is a copper coated wire for

general purpose welding with the gas-metal arc process. It contains sufficient deoxidizers to

produce sound welds on killed and semi-killed steels and adequate welds on rimmed steels.

Carbon dioxide or argon-CO2 shielding gas mixtures may be used. The smaller diameters (up

to .045") are especially useful for welding light gauge mild steel in all positions. Among the

many applications for which Spoolarc 29S may be used are farm equipment, metal furniture,

iron work, trailers, truck bodies, metal fixtures, light vessels, and hoppers.




Silicon 0.27%

B. Typical Mechanical Properties of the Weld Metal Using CO2 Shielding Gas

Yield Point, psi 60,100

Tensile Strength, psi 75,000

% Elongation (2") 32

Charpy V-Notch Impacts 95 ft.-lbs. @0°F

6.6.3 Spoolarc 85 (AWS Class ER70S-4) - Spoolarc 85 is a copper plated gas-metal

arc welding wire. This wire contains more manganese and silicon for greater deoxidation than

ER70S-3 wire. The additional levels of deoxidizers provides more improved rust and mill

scale tolerance, while improving bead cosmetics.




Silicon 0.39% Copper 0.16%






Welding












Electrodes




Filler Metals


LESSON VI

6.6.4 Spoolarc 86 (AWS Class ER70S-6) - Spoolarc 86 is a copper plated gas-metal

arc welding wire. Containing a high level of deoxidizers, it produces sound welds in all carbon

steels using CO2 shielding gas, argon/CO2 and argon/O2 mixtures. The arc is quiet and very

stable. High speed, high deposition welds can be made with argon-oxygen gas mixtures.

Ideal for welding sheet metal where smooth weld beads with good wetting action are desir-

able. It may be used to weld carbon steels that have a moderate amount of rust or mill scale.

Spoolarc 86 can also be used for out-of-position welding with the short-circuit transfer method,

making it ideal for pipe welding. Other applications are for bridges, building construction,

boiler and pressure vessels, storage tanks, auto parts, and construction equipment.




Silicon 0.57%





Charpy V-Notch Impacts 31 ft.-lbs. @-20°F

6.6.5 Spoolarc 87HP (AWS Class ER70S-7) - Spoolarc 87HP is a high manganese

carbon steel wire. It features an optimized manganese to silicon ratio to produce excellent

appearing welds over a wide range of welding parameters. It also produces excellent weld

metal mechanical properties and welds over moderate amounts of rust and scale.




Silicon 0.65%

B. Typical Mechanical Properties of the Weld Metal Using 75% Ar/25% CO2






Welding












Electrodes




Filler Metals


LESSON VI


6.7.0.1 This specification is entitled Specification for Low Alloy Steel Filler Metal for GasShielded Arc Welding. It covers the solid bare wires for welding those steels commonly re-

ferred to as the chromium-molybdenum (chrome-molys), manganese-molybdenum

(manganese-molys), nickel alloy and other low alloy steels. The wires referred to in this lesson

are for use with the gas-metal arc welding process and also may be used as filler metals for

the GTAW process.

6.7.0.2 The letter-number designations have the same significance as those used in the

carbon steel specification shown in Figure 4. Using ER80S-B2 as an example, the letters ER

indicate that it is an electrode or a welding rod; will produce weld metal of 80,000 psi tensile

strength (80); is a solid bare wire (S) of a specific chemical composition (B2) as described in

Figure 8.Major Alloying Elements - % By Weight

AWS Class Carbon Chromium Molybdenum

ER80S-B2L *0.05 1.20 - 1.50 0.40 - 0.65

ER80S-B2 0.07 - 0.12 1.20 - 1.50 0.40 - 0.65

ER80S-B3L 0.05 2.30 - 2.70 0.90 - 1.20

ER80S-B3 0.07 - 0.12 2.30 - 2.70 0.90 - 1.20

* Single figure denotes maximum

CHEMICAL COMPOSITION CHROMIUM-MOLYBDENUM SOLID BARE WIRES

FIGURE 8

6.7.1 The Chromium-Molybdenum Types (Cr-Mo) - The letter “B” designates a Cr-Mo

wire to be used for welding the Cr-Mo pressure vessel steels, and the number that follows desig-

nates the chemical composition of the filler metal. If the last number is followed by an “L”, it

indicates that the wire has a low carbon content.

6.7.1.1 Figure 8 shows only the major chemical composition requirements for these filler

metals. For complete requirements, see AWS A5.28-96 Filler Metal Specification.

6.7.1.2 Figure 9 shows the mechanical property requirements for the Cr-Mo weld metal.

6.7.1.3 Filler metals of the preceding classifications are used to weld the 1/2 Cr-1/2 Mo, 1

Cr-1/2 Mo, 1-1/4 Cr-1/2 Mo, and 2-1/4 Cr-1 Mo steels that are used in welding high tempera-

ture piping and pressure vessels. They provide a degree of corrosion resistance and are

used for welding dissimilar grades of Cr-Mo steels and carbon steels.


Welding












Electrodes




Filler Metals


LESSON VI

6.7.1.4 These filler metals may be used with all GMAW metal transfer modes. The AWS

mechanical properties and impact properties are established using argon plus 1-5% oxygen

as a shielding gas. Straight CO2 and argon-CO2 mixtures may be used. These mixtures will

produce welds with deeper penetration, although impact properties will be somewhat lower.

6.7.1.5 Welding low alloy high strength steels with the GMAW process requires that pre-

heat, interpass, and post-weld temperatures be closely controlled to prevent cracking. The low

carbon filler metals designated by the letter “L” will provide greater resistance to cracking, and

are more suitable when post-weld heat treatment is not practical or possible.

6.7.2 The Nickel Alloy Types (Ni) - The letters

“Ni” designate that the filler metal is a nickel alloy

wire for welding the nickel alloy steels. The number

following the letters designates the chemical

composition of the wire. Figure 10 shows only the

amount of nickel required in the wire under this

specification. For complete chemical

requirements, see AWS A5.28-96 Filler Metal

Specification.

6.7.2.2 Figure 11 shows the mechanical property requirements for nickel alloy weld metals.

Tensile YieldStrength Strength Elongation Impact

AWS Class psi psi in 2", % Properties

ER80S-B2 80,000 68,000 19 Not Required

ER80S-B2L 80,000 68,000 19 Not Required

ER90S-B3 90,000 78,000 17 Not Required

ER90S-B3L 90,000 78,000 17 Not Required

All values are mininums

MECHANICAL PROPERTIES OF Cr - Mo WELD METAL

FIGURE 9

NickelAWS Class % by Weight

ER80S-Ni1 0.80 - 1.10

ER80S-Ni2 2.00 - 2.75

ER80S-Ni3 3.00 - 3.75

NICKEL REQUIREMENTS

NICKEL ALLOY SOLID BARE WIRESFIGURE 10


AWS Class psi psi in 2", Min. Properties

ER80S-Ni1 20 ft-lb @ -50°F

ER80S-Ni2 80,000 68,000 24 20 ft-lb @ -80°F

ER90S-Ni3 20 ft-lb @ -100°F

All values are mininums

MECHANICAL PROPERTIES OF NICKEL ALLOY WELD METALS

FIGURE 11

}


Welding












Electrodes




Filler Metals


LESSON VI

6.7.2.3 Nickel alloy wires are used for welding the nickel alloy steels that are employed in

applications requiring 80,000 psi tensile strength and good toughness at low temperatures.

The ER80S-Ni1 wire deposits weld metal containing a nominal 1% nickel, similar to an

E8018C3 coated electrode. The ER80S-Ni2 deposits weld metal containing a nominal 2-1/

2% nickel, similar to an E8018C1 coated electrode and the ER80S-Ni3 deposits weld metal

containing a nominal 3-1/2% nickel, similar to an E8018C2 coated electrode.

6.7.2.4 The weld metal deposit will have a chemical composition similar to the chemical

composition of the wire when argon-O2 shielding gas is used. If CO2 is used as a shieldinggas, the deoxidizing elements, such as manganese and silicon, will be considerably reduced

in the weld metal. The recommended shielding gas is argon plus 1.0 to 5.0% oxygen. Weld-

ing the nickel alloy steels usually requires that the weldment be preheated before welding, and

the interpass temperature controlled. It may also be necessary to subject the weldment to post

weld heat treatment, depending on the alloy and thickness of the material.

6.7.3 The Manganese-Molybdenum Types ”Mn-Mo” - The suffix letter “D” designates

a manganese-molybdenum wire to be used for welding the manganese-molybdenum steels.

The number that follows designates the chemical composition of the wire.

6.7.3.1 There is only one manganese-moly wire in this classification. It is designated asER80S-D2 and was formerly classified as E70S-1B in AWS Specification A5.18-89 (since

updated to A5.18-93).

A. Chemical Composition Requirements for ER80S-D2 Bare Solid Wire

Carbon 0.07-0.12% Nickel 0.15% max.

Manganese 1.60-2.10% Copper 0.50% max.

Silicon 0.50-0.80% Phosphorus0.025% max.

Molybdenum 0.40-0.60% Sulfur 0.025% max.

B. Mechanical Property Requirements ER80S-D2 Weld Metal

Yield Strength, psi 60,000





Welding












Electrodes




Filler Metals


LESSON VI

6.7.3.2 This wire is suitable for welding a large variety of low alloy and carbon steels. It is

excellent for out-of-position work and contains molybdenum for increased strength. Argon-O2

and argon-CO2 gas mixtures are recommended for maximum mechanical properties, but

welds made with CO2 shielding gas will still deliver mechanical properties within the specifica-tion limits due to the high level of manganese and silicon in the wire. The high level of deoxi-

dizers allows this wire to be used over moderate amounts of rust and mill scale.

6.7.4 Spoolarc 83 (AWS Class ER80S-D2) - Spoolarc 83 is a small diameter copper

coated solid wire for gas metal arc welding. Because of the additional alloys, manganese,

and molybdenum, the deposit is adequate for high strength low alloy steels. In addition, the

higher levels of deoxidizers provide improved rust and mill scale tolerance, as well as

out-of-position capabilities. This wire is most commonly used on pressure vessel and gas

transmission line applications.




Silicon 0.27% Molybdenum 0.38%

B. Typical Mechanical Properties of the Weld MetalUsing CO2 Shielding GasYield Strength, psi 77,000



% Reduction of Area 66.8


6.7.5 Spoolarc Hi-84 (AWS Class ER80S-D2) - Spoolarc Hi-84 is a 1/2% Mo wire that

has been microalloyed to produce exceptional impact toughness at temperatures as low as

-50°F. The weld metal deposit produces a high strength weld with good tolerance of rust and

mill scale.


Carbon 0.11% Nickel 0.15%

Manganese 1.90% Chromium 0.08%

Silicon 0.60% Ti and Zr 0.017%

Molybdenum 0.50%


Welding












Electrodes




Filler Metals


LESSON VI

B. Typical Mechanical Properties of the Weld MetalUsing 98% Ar/2% O2

Shielding Gas

Yield Strength, psi 99,000




51 ft.-lbs. @-50°F6.7.6 All Other Low Alloy Types

6.7.6.1 Solid wires for welding the low alloy high tensile steels that do not fit into the com-

mon Cr-Mo, Ni alloys and Mn-Mo types, fall into the “all other” category. They produce welds

with very high strength and very good notch toughness. These alloys are designated by the

numbers “1”, “2”, or "G" as shown in Figure 12.

6.7.6.2 Only the major alloying elements for these wires are shown above. For complete

chemical composition requirements, see AWS Filler Metal Specification A5.28-96.

Major Alloying Elements - % By Weight

AWS Class Carbon Manganese Nickel Chromium Molybdenum

ER100S-1 0.08* 1.25 - 1.80 1.40 - 2.10 0.30 0.25 - 0.55

ER100S-2 0.12 1.25 - 1.80 0.80 - 1.25 0.30 0.20 - 0.55

ER110S-1 0.09 1.40 - 1.80 1.90 - 2.60 0.50 0.25 - 0.55

ER120S-1 0.10 1.40 - 1.80 2.00 - 2.80 0.60 0.30 - 0.65

ERXXS-G As agreed between supplier and purchaser

*Single values are maximums.

CHEMICAL COMPOSITION - OTHER LOW ALLOYS - SOLID BARE WIREFIGURE 12


AWS Class psi psi in 2", Min. Properties

ER100S-1 100,000 88,000 - 102,000 16

ER100S-2 100,000 88,000 - 102,000 16

ER110S-1 110,000 95,000 - 107,000 15

ER120S-1 120,000 105,000 - 122,000 14

ERXXS-G * As agreed between supplier and purchaser

* Ultimate tensile strength must meet value placed after "ER"

WELD METAL MECHANICAL PROPERTIES REQUIREMENTS - OTHER LOW ALLOYS

FIGURE 13

} 50 ft-lb @ -60°F

6.7.6.3 The mechanical requirements for the weld metal deposited in this classification are

shown in Figure 13.


Welding












Electrodes




Filler Metals


LESSON VI

6.7.6.4 The wires in this category were originally developed for the high strength steels in

military applications. Today, they are used in structural and other applications requiring tensile

strengths in excess of 100,000 psi and toughness at low temperatures. Common types of

steels welded with these wires are the T-1, HY-80, HY-100, NAXtra100 and others.

6.7.7 Spoolarc 95 and 120 (AWS Class ER100S-1 and ER120S-1) - Spoolarc 95 and

120 are Military grade high strength wires designed for welding HY-80 and HY-100 steels.

Both wires produce excellent mechanical properties and low temperature toughness. They

can be used for nonmilitary applications requiring high strength and low temperature tough-

ness.

A. Typical Chemical Analysis of the WireSpoolarc 95 Spoolarc 120

Carbon 0.07% 0.07%

Manganese 1.40% 1.30%

Silicon 0.35% 0.35%

Molybdenum 0.35% 0.45%

Chromium 0.20% 0.40%

Nickel 1.80% 2.60%

B. Typical Mechanical Properties of the Weld Metal Using 98% Ar/

2% O2 Shielding GasSpoolarc 95 Spoolarc 120

Yield Strength, psi 95,000 112,000




ft.-lbs. @-0°F 93 100

ft.-lbs. @-60°F 65 75

The suffix letter “G” applies to solid wire electrodes and welding rods that do not fall into any of

the other classes in this specification. They must have at least one of the following: 0.50%

nickel, 0.30% chromium, or 0.20% molybdenum. They must pass the radiographic soundness

test for porosity or inclusions, and also the weld metal tensile tests that are spelled out in detail

in this specification.


Welding












Electrodes




Filler Metals


LESSON VI

6.8 WIRES AND FLUXES FOR SUBMERGED ARC

WELDING OF CARBON STEELS

6.8.0.1 In submerged arc welding (SAW), the weld metal quality, mechanical properties and

bead shape are the result of the electrode* (or wire) and flux combination used in a particular

application. Unlike coated electrodes, where the core wire and flux coating are inseparable,

various fluxes may be used with a given wire to produce the desired results. The weld area is

shielded by this blanket of flux. When molten, the flux forms a protective layer above the molten

weld metal that not only provides for specific mechanical properties, but also gives the bead

some shape.

Note - * The American Welding Society has standardized on the term “electrode” when referring to the wires used inSAW since these wires always carry the welding current. In this Lesson, the terms wire and electrode will be usedinterchangeably and will have the same meaning.

6.8.0.2 The advantages for using SAW are numerous. They include:

a. High rates of travel.

b. High deposition rates.

c. Superior weld metal integrity.

d. Reduce edge preparations.

e. Improved operator comfort and safety.

6.8.1 Equipment - The SAW process can utilize either an AC or DC power supply. DC is

most often chosen because it provides the following advantages:

a. Good control over bead shape and penetration.

b. Best arc starting characteristics on either electrode positive (+) or

electrode negative (-).

c. DCEN offers 10-15% higher deposition rates than AC.

d. DCEP offers better bead shape control and deeper penetration.

e. Lowest cost to purchase.

6.8.1.1 AC, on the other hand, provides features as well. They include:

a. Reduced arc blow (especially when amperage exceeds 800 amps or when

welding on heavy sections).

b. Increased flexibility when used in combination with multiple wires (DC-AC,

AC-AC, or AC-AC-AC).


Welding












Electrodes




Filler Metals


LESSON VI

6.8.2 Welding Filler Metals - A continuous bare electrode is fed into a blanket of granular

flux that covers the weld joint. Once current is applied to the electrode, usually ranging in size

from 1/16" to 1/4" diameter, an arc is established and the base metal, the electrode, and the

flux melt to form a molten puddle. The solid electrode is usually copper coated, except for

certain nuclear applications, to minimize contact tip wear and assure good current transfer to

the wire. The molten flux flows to the surface to form a slag while the metallic components

create a weld.

6.8.2.1 Since high currents are usually applied to the electrode, extremely high deposition

rates are possible with SAW. The current and voltage ranges reflected in Figure 14 will pro-

vide information on the deposition capability of SAW.

Deposition Rate*

Wire Diameter Current Ranges Volts lbs./hr.

1/16" (1.6 mm) 150 - 500 19 - 27 5-17 (2.27- 7.71 Kg)

5/64" (2.0 mm) 200 - 600 20 - 28 6-22 (2.72- 9.98 Kg)

3/32" (2.4 mm) 250 - 700 22 - 30 8-24 (3.63-10.89 Kg)

1/8" (3.2 mm) 300 - 900 23 - 32 8-28 (3.63-12.70 Kg)

5/32" (4.0 mm) 400 - 1000 25 - 34 9-30 (4.08-13.61 Kg)

3/16" (4.8 mm) 500 - 1100 27 - 36 12-34 (5.44-15.42 Kg)

7/32" (5.6 mm) 600 - 1200 30 - 37 20-44 (9.07-19.96 Kg)

1/4" (6.4 mm) 700 - 1600 30 - 38 18-56 (8.16-25.40 Kg)

OPERATING RANGES AND DEPOSITION RATES(DCEP - ESO AVERAGE 8 X WIRE DIAMETER)

FIGURE 14

6.8.2.2 Composite submerged electrodes, as described in Lesson II, are not normally used

for welding carbon steel. They are, however, used in welding low alloy high strength materials.

Current and voltage ranges will differ, along with their respective deposition rates. These

electrodes will be discussed late in this lesson.

6.8.3 Fluxes for Carbon Steel Electrodes - The granular powder, referred to as “flux”,

under which the welding takes place, shields the molten puddle from the atmosphere, cleans

the weld metal, and influences the mechanical properties and shape of the weld bead. The flux

also acts as a barrier preventing the heat from escaping, permitting the desired depth of

penetration (this can vary with current and polarity). Fluxes differ as a result of the method

used to manufacture them.


Welding












Electrodes




Filler Metals


LESSON VI

6.8.3.1 Fluxes are classified as either “bonded” or “fused” based on the manufacturing

methods. When manufacturing a bonded flux, fine particles of various ingredients are dry

mixed and bonded together with a sodium silicate or other similar compound. The wet

bonded mix is pelletized and baked at relatively low temperatures. The pellets are then broken

into smaller pieces and screened into proper sizes and packaged for shipment.

6.8.3.2 The advantages of “bonded” fluxes are that additional deoxidizers and alloying

elements can be added. Secondly, this type of flux generally has a lower consumption rate.

The major disadvantage of a bonded flux is their inherent moisture pick-up, especially when

opened, bags are allowed to remain exposed to the atmosphere.

6.8.3.3 “Fused” fluxes are manufactured under different conditions. The raw materials are

mixed together and then melted at very high temperatures in a furnace. The molten mixture is

cooled either by pouring it onto a chill table and allowed to cool, or shooting the molten mixture

with a stream of water. The glass-like material is crushed, then screened to a particular par-

ticle size and packaged for shipment.

6.8.3.4 “Fused” fluxes offer several advantages to the user, including much less moisture

pick-up than bonded fluxes. Secondly, the user has better control of weld metal properties

after recycling used flux. The major disadvantage with fused fluxes is the inability to add

additional deoxidizers and alloys during manufacturing.

6.8.3.5 Fluxes are also described as “active” or “neutral”, depending on the amount of

alloying elements or deoxidizers (especially manganese or silicon) that are transferred to the

weld metal.

a. Active Fluxes - contain manganese and silicon. Active fluxes are readily trans-

ferred to the weld metal. The amount transferred depends on the amount of flux consumed per

unit of wire. Excessively high manganese and silicon transferred to the weld can cause weld

metal cracking. Active fluxes are recommended for single pass or limited multipass welding

applications. Changes in arc voltage can greatly effect the flux consumption per unit of wire

and the weld metal properties. It is, therefore, crucial to adhere to the manufacturer’s sug-

gested welding parameters.

b. Neutral Fluxes - produce little significant change in weld metal properties as aresult of arc voltage. The primary purpose for neutral fluxes is that they can be used on multi-

pass weldments, especially those that exceed one inch thickness. The disadvantage for

neutral fluxes is their low tolerance to rust and mill scale. Generally speaking, active fluxes are

used with carbon steel electrodes, while neutral fluxes are recommended for both carbon and

low alloy steels.


Welding












Electrodes




Filler Metals


LESSON VI

Costs


6.9.0.1 This AWS specification is entitled Specification for Carbon Steel Electrodes andFluxes for Submerged Arc Welding. It classifies the electrodes on the basis of their chemical

composition as shown in Figure 15A. The fluxes are classified on the basis of the mechanical

properties of the weld metal they deposit with a particular classification of electrode as shown

in Figure 15B.

Electrode When Used, Indicates Electrode MadeFrom Silicon-Killed (Deoxidized) Steel.

E X X X K

PercentCarbon

By Weight

8 = 0.10 Max.12 = 0.05 - 0.1513 = 0.07 - 0.1914 =15 =}0.10 - 0.20

PercentManganeseBy Weight

L = 0.25 - 0.60M = 0.80 - 1.40H = 1.70 - 2.20

ELECTRODE DESIGNATIONS FOR SUBMERGED ARC WELDING CARBON STEELFIGURE 15A

F X X X

A = As WeldedP = Postweld Heat Treatment

1150° for 1 Hour

Flux

F6XX F7XX

Tensile 60,000 70,000Strength to to

psi 80,000 95,000

YieldStrength 48,000 58,000

psi Min. Min.

Elongation 22 22% in 2" Min. Min.

FLUX DESIGNATIONS FOR SUBMERGED ARC WELDING CARBON STEELFIGURE 15B

Impact RequirementsCharpy V-Notch

Z No Requirement0 0° F2 -20 °F4 -40 °F5 -50 °F6 -60 °F8 -80 °F

}20 ft-lbs @


Welding












Electrodes




Filler Metals


LESSON VI

6.9.0.2 For example, when a manufacturer assigns the AWS classification EM12K to a

given wire or electrode, he certifies that his product is an electrode (E); containing a medium

manganese content of 0.80 to 1.40% (M); containing a carbon content of 0.05 to 0.15% (12);

and is made from a heat of silicon-killed steel (K).

6.9.0.3 When classifying a flux as to mechanical properties, it is necessary to also specify

the electrode or wire with which these properties are obtained. As an example, the classifica-

tion F7P6-EM12K certifies that the product is a submerged arc flux (F); will provide weld metal

of 70,000 to 95,000 psi tensile strength, a minimum of 58,000 psi yield strength and a mini-

mum of 22% elongation in two inches after the weldment has been subjected to a postweld

heat treatment of 1150°F for one hour (P); and will have a minimum charpy V-notch impact of

20 ft.-lbs. at -60°F when used with an EM12K wire.

6.9.0.4 The eleven types of carbon steel electrodes listed in AWS A5.17-89 are as follows:

A. Low Manganese Steel Electrodes

1) EL8

2) EL8K

3) EL12B. Medium Manganese Steel Electrodes

1) EM12

2) EM12K

3) EM13K

4) EM14K

5) EM15KC. High Manganese Steel Electrodes

1) EH11K

2) EH12K

3) EH14

6.9.0.5 The carbon and manganese content of these wires are shown in Figure 15. For

complete chemical composition of these wires, see AWS Filler Metal Specification A5.17-89.


Welding












Electrodes




Filler Metals


LESSON VI

6.10 ESAB WIRES AND FLUXES FOR CARBON STEEL

SUBMERGED ARC WELDING

6.10.1 Spoolarc 81 (AWS Class EM12K) - Spoolarc 81 is a general purpose submerged

arc wire for moderately clean material. Applications include low and medium structural carbon

steel, longitudinal and circumferential welds on low to medium strength pressure vessel steels

and some offshore and ship fabrication.





B. Typical Mechanical Properties (* See note following Unionmelt 80)

Weld UTS YS % CVN (ft-lbs) AWS/ASMEFlux Cond. (ksi) (ksi) Elong. @-20°F SFA 5.17 Class

231 AW 82-90 75-80 25-29 24-29 F7A2-EM12K

429 AW 75-82 65-72 25-30 35-45 F7A2-EM12K

SR(a) 70-75 58-64 25-30 35-45 @-40°F F7P4-EM12K

80 AW 70-75 60-65 27-31 35-45 F6A2, F7A2-EM12K

(a) Stress-Relieved @1150°F - 1 hr.

6.10.2 Spoolarc 29S (AWS Class EM13K) - Spoolarc 29S has increased amounts of sili-

con for both improved puddle fluidity and rust and mill scale tolerance. This wire is not recom-

mended for material greater than 1" thickness. Applications include single pass high speed

fillets on both low and medium carbon steels.






Weld UTS YS % CVN (ft-lbs) AWS/ASMEFlux Cond. (ksi) (ksi) Elong. @-20°F SFA 5.17 Class231(a) AW 85-94 77-83 25-29 25-30 @ 0°F. F7A0-EM13K429 AW 80-85 66-73 25-30 28-35 @-20°F. F7A2-EM13K(a) This combination of flux and wire is only recommended for single pass welding.


Welding












Electrodes




Filler Metals


LESSON VI

6.10.3 Spoolarc 80 (AWS Class EL12) - Spoolarc 80 has the least amount of manganese

and silicon and is therefore intended for clean material. The major advantage of this wire is the

improved ductility, ease of machining and improved crack resistance. Applications include high

speed fillets on axle housings and wheel rims and thick heavy sections on highly restrained

multipass weldments.





B. Typical Mechanical Properties

Weld UTS YS % CVN (ft-lbs) AWS/ASMEFlux Cond. (ksi) (ksi) Elong. @-20°F SFA 5.17 Class

231(a) AW 71-77 60-69 26-31 15-25 @ 0°F. F7AZ-EL12

429 AW 64-69 55-60 26-32 45-55 @-20°F. F6A2-EL12

(a) This combination of flux and wire is only recommended for single pass welding.

6.10.4 Unionmelt 231 - Unionmelt Flux 231 is an active flux that is limited to a maximum

plate thickness of one inch or less and operated at less than 36 volts. Applications include single

and multipass flat and horizontal fillets over rust and mill scale. This flux can be used with Spoolarc

81, 29S and 80.

A. Typical Deposit ChemistryAWS/ASME

Wire Material C Mn Si Cu SFA 5.17

81 A516 0.08 1.20 0.55 0.11 F7A2-EM12K

29S(a) A285 0.08 1.30 0.70 0.10 F7A0-EM13K

80 A36 0.07 0.90 0.40 0.11 F7AZ-EL12


Spoolarc Weld UTS YS % CVNMaterial Wire Condition (ksi) (ksi) Elong. (ft.-lbs.)

A516 81 AW 82-90 75-80 25-29 24-29 @-20°F

A285 29S(a) AW 85-94 77-83 25-29 25-30 @ 0°F

A36 80 AW 71-77 60-69 26-31 15-25 @ 0°F

(a) Unionmelt Flux 231 and Spoolarc 29S are recommended for single pass welding only.


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LESSON VI

6.10.5 Unionmelt 429 - Unionmelt Flux 429 is a neutral bonded flux designed for multipass

welding. Weld metal chemistries are excellent both as-welded and stress-relieved. Applica-

tions include deep groove multipass welds found on pressure vessels and offshore oil fabrica-

tion. Commonly used with hand-held semi-automatic equipment. This flux can be used with

Spoolarc 81 and 29S.

A. Typical Deposit Chemistry

AWS/ASMEWire Material C Mn Si Cu SFA 5.17

81 A36 0.07 1.25 0.50 0.14 F7A2-EM12K

29S A285 0.06 1.28 0.70 0.12 F7A2-EM13K



A36 81 AW 75-90 75-80 25-29 24-29 @-20°F

SR(a) 70-75 58-64 25-30 35-45 @-40°F

A285 29S AW 80-85 66-73 25-30 28-35 @-20°F

(a) Stress-Relieved @1150°F - 1 hr.

6.10.6 Unionmelt 282 - Unionmelt Flux 282 is an active bonded flux designed for high speed

single pass welding on thin gauge material. The weld metal fluidity and high travel speeds make

this flux extremely versatile. Applications include longitudinal welds on structural steel, as well as

circumferential seams on spiral pipe. This flux is best used with Spoolarc 81 and 29S.

A. Typical Mechanical Properties (* See note following Unionmelt 80)

Spoolarc Wire Tested Per AWS A5.17-89

Spoolarc 81 Conforms to F7A0-EM12K (20 ft.-lbs. @ 0°F)

Spoolarc 29SConforms to F7A0-EM13K (20 ft.-lbs. @ 0°F)


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LESSON VI

6.10.7 Unionmelt 50 - Unionmelt Flux 50 is a neutral fused flux developed for high speed

welding of thin gauge material (usable on relatively clean steel only). In addition, this flux works

equally well for surfacing and build-up applications. Because this flux is a fused type, it is particu-

larly resistant to moisture pick-up. Applications include propane cylinders and hot water tanks.

This flux can be used with Spoolarc 81 and 80.


Spoolarc AWS/ASMEMaterial Wire C Mn Si SFA 5.17

A36 81 0.05 0.93 0.30 F7A2-EM12K

Stress-Relieved F6P4-EM12K

A36 80 0.05 1.17 0.42 F6A2-EL12



A36 81 AW 70-75 60-65 24-28 25-40 @-20°F

SR(a) 65-70 50-55 25-29 75-80 @-20°F

A36 80 AW 65-70 55-60 24-28 30-40 @-20°F

(a) Stress-Relieved @1150°F - 8 hrs.

6.10.8 Unionmelt 80 - Unionmelt Flux 80 is a neutral fused flux for multipass, heavy plate

welding applications. Superior mechanical properties on clean material is available in both

as-welded and stress-relieved conditions. The low moisture pick-up of this flux helps reduce the

handling and storage casts. Applications include carbon and low alloy steels used to fabricate

pressure vessels. This flux can be used with Spoolarc 81 and 80.


Spoolarc AWS/ASMEMaterial Wire C Mn Si SFA 5.17

A36 81 0.06 1.0 0.50 F6A2, F7A2-EM12K

A36 80 0.05 0.60 0.40 F6A2-EL12

B. Typical Mechanical Properties *


A36 81 AW 70-75 60-65 26-30 35-45 @-20°F

A36 80 AW 65-70 55-60 26-30 45-55 @-20°F

* NOTE: The data listed for both the deposit chemistry and mechanical properties are based on laboratory tests.Results may vary according to your specific welding parameters or base metal conditions. It is,therefore, important that the user run tests that closely duplicate their actual production conditions.


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LESSON VI

6.11 ELECTRODES AND FLUXES FOR SUBMERGED ARC

WELDING OF THE LOW ALLOY STEELS

6.11.0.1 In an earlier lesson, we learned that most low alloy coated electrodes have a mild or

carbon steel core wire, and the alloying elements, that produce the higher tensile strengths or

improved impact properties, are in the electrode coating. In the case of stainless steel coated

electrodes, a stainless steel core wire is used, and the elements that determine the specific

analysis of the weld metal are included in the coating. In submerged arc welding, the choice

exists as to the wire-flux combination that will produce the required end result.

6.11.1 Electrodes and Fluxes for Welding the Alloys - Electrodes for welding the low

alloy steels are available as low alloy solid wires or composite electrodes. Composite elec-

trodes are similar to flux cored electrodes, but since they are used with a granular flux, the core

contains mostly the necessary alloying elements. The outer sheath may be a carbon or alloy

steel. Submerged arc wires are available in diameters ranging from 1/16" to 1/4" diameter.

6.11.1.1 Welding the low alloy steels with the submerged arc process may be accomplished

in several different manners. They are:

a. A solid wire that has a sufficient amount of alloying elements included in the chemistry

of the wire as manufactured, and a neutral flux that shields the weld and influences bead

shape, but has a minimal affect on weld metal chemistry.

b. A composite wire that contains the necessary alloying elements in the core and/or the

steel sheath, used in conjunction with a neutral flux.

c. A solid carbon steel wire may be used, such as an EM12K type, in combination with a

flux that contains the necessary alloying elements to produce the desired low alloy weld

metal.


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®COPYRIGHT 2000 THE ESAB GROUP, IN

LESSON VI


6.12.0.1 This AWS specification is entitled Specification for Low Alloy Steel Electrodes andFluxes for Submerged Arc Welding. Since there are two types of welding wires, solid and

composite, each must be considered in a different manner. Solid wires are classified by their

as manufactured chemical analysis, but this is not possible with composite wires because the

outer steel sheath and the core ingredients combine to produce the resultant weld metal.

Therefore, composite wires are classified as to the weld metal chemical composition as are

coated electrodes.

6.12.0.2 The fluxes for welding low alloys with the submerged arc process are classified by

the weld metal mechanical properties they produce with a given wire or electrode. Figure 16

shows the classification of fluxes and electrodes under this specification.

Impact RequirementsCharpy V-Notch

Z No Requirement0 0° F2 -20 °F4 -40 °F5 -50 °F6 -60 °F8 -80 °F10 -100 °F15 -150 °F

}20 ft-lbs @

Tensile YieldStrength Strength Elongation

psi psi % in 2"

F7XX 70,000 - 95,000 58,000 22F8XX 80,000 - 100,000 68,000 20F9XX 90,000 - 110,000 78,000 17F10XX 100,000 - 120,000 88,000 16F11XX 110,000 - 130,000 98,000 15F12XX 120,000 - 140,000 108,000 14

F X X X

Flux A = As WeldedP = Postweld Heat Treatment Time & Temp. per AWS A5.17-89

FLUX DESIGNATIONS

ELECTRODE DESIGNATIONS

FLUX AND ELECTRODE DESIGNATIONS FOR SUBMERGED ARC WELDING - LOW ALLOY STEELS

FIGURE 16

Indicates Composite Electrode.Omission Indicates Solid Wire

Electrode

Classification of Electrode -2, 3, or 4 Numbers or Letters.

Chemical Composition of Weld Metal -1, 2, or 3 Numbers or Letters

Optional DiffusableHydrogen DesignatorUsed Only for Some Nuclear Requirements

E C X X X N - X N H X

1 or 2 Digits


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LESSON VI

6.12.1 Composition Requirements for Solid Low Alloy Electrodes - The listing in

Figure 17 indicates only the major alloying elements of each electrode type. For complete

chemical composition requirements, see AWS A5.23-90.

C = Carbon Ni = Nickel

Mn = Manganese Mo = Molybdenum

Cr = Chromium

ELECTRODECLASSIFICATION C Mn Cr Ni Mo Si

Carbon SteelEL12 0.04 - 0.14 0.25 - 0.60 — — — 0.10EM12K 0.05 - 0.15 0.80 - 1.25 — — — 0.10 - 0.35

Carbon-MolybdenumEA1 0.07 - 0.17 0.65 - 1.00 — — 0.45 - 0.65 0.20EA2 0.07 - 0.17 0.95 - 1.35 — — 0.45 - 0.65 0.20EA3 0.10 - 0.18 1.65 - 2.15 — — 0.45 - 0.65 0.20EA3K 0.07 - 0.12 1.60 - 2.10 — — 0.40 - 0.60 0.50 - 0.80EA4 0.07 - 0.17 1.20 - 1.70 — — 0.45 - 0.65 0.20

Chromium MolybdenumEB1 0.10 0.40 - 0.80 0.40 - 0.75 — 0.45 - 0.65 0.05 - 0.30EB2 0.07 - 0.15 0.45 - 0.80 1.00 - 1.75 — 0.45 - 0.65 0.05 - 0.30EB2H 0.28 - 0.33 0.45 - 0.65 1.00 - 1.50 — 0.40 - 0.65 0.55 - 0.75EB3 0.05 - 0.30 0.40 - 0.80 2.25 - 3.00 — 0.90 - 1.10 0.05 - 0.30EB5 0.18 - 0.23 0.40 - 0.70 0.45 - 0.65 — 0.90 - 1.20 0.40 - 0.60EB6 0.10 0.35 - 0.70 4.50 - 6.50 — 0.45 - 0.65 0.05 - 0.50EB6H 0.25 - 0.40 0.75 - 1.00 4.80 - 6.00 — 0.45 - 0.65 0.25 - 0.50EB8 0.10 0.30 - 0.65 8.00 - 10.50 — — 0.05 - 0.50

Nickel SteelENi1 0.12 0.75 - 1.25 0.15 0.85 - 1.25 0.30 0.05 - 0.30ENi2 0.12 0.75 - 1.25 — 2.10 - 2.90 — 0.05 - 0.30ENi3 0.13 0.60 - 1.20 0.15 3.10 - 3.80 — 0.05 - 0.30ENi4 0.12 - 0.19 0.60 - 1.00 — 1.60 - 2.10 0.10 - 0.30 0.10 - 0.30ENi1K 0.12 0.80 - 1.40 — 0.75 - 1.25 — 0.40 - 0.80

Other Low Alloy SteelEF1 0.07 - 0.15 0.90 - 1.70 — 0.95 - 1.60 0.25 - 0.55 0.15 - 0.35EF2 0.10 - 0.18 1.70 - 2.40 — 0.40 - 0.80 0.40 - 0.65 0.20EF3 0.10 - 0.18 1.70 - 2.40 — 0.70 - 1.10 0.45 - 0.65 0.30EF4 0.16 - 0.23 0.60 - 0.90 0.40 - 0.60 0.40 - 0.80 0.15 - 0.30 0.15 - 0.35EF5 0.10 - 0.17 1.70 - 2.20 0.25 - 0.50 2.30 - 2.80 0.45 - 0.65 0.20EF6 0.07 - 0.15 1.45 - 1.90 0.20 - 0.55 1.75 - 2.25 0.40 - 0.65 0.10 - 0.30EM2 0.10 1.25 - 1.80 0.30 1.40 - 2.10 0.25 - 0.55 0.20 - 0.60EM3 0.10 1.40 - 1.80 0.55 1.90 - 2.60 0.25 - 0.65 0.20 - 0.60EM4 0.10 1.40 - 1.80 0.60 2.00 - 2.80 0.30 - 0.65 0.20 - 0.60EW 0.12 0.35 - 0.65 0.50 - 0.80 0.40 - 0.80 — 0.20 - 0.35EG No Requirements

Single Figures are Maximums

MAJOR CHEMICAL COMPOSITION REQUIREMENTSSOLID WIRE SUBMERGED ARC WELDING ELECTRODES. AWS A5.23-90

FIGURE 17


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LESSON VI

6.12.1.1 Figure 17 lists two carbon steel wires (EL12 and EM12K) that are the same as

those listed in AWS A5.17-89, the specification for mild and carbon steels. They appear here

only because they can be used with fluxes that contain sufficient alloying elements to deposit a

low alloy weld metal.

6.12.1.2 Although all of the low alloy electrodes in AWS Specification A5.23-90 are listed

here, a complete knowledge of their uses and applications are beyond the scope of this

course. They are presented here so that you will be familiar with the various AWS designa-

tions.

6.12.1.3 As an example, a manufacturer of a solid wire electrode may assign the AWS

classification EB3. Under this specification, he certifies that this wire is an electrode (E), the

chemical composition is a chrome-moly type (B) containing a nominal 2-1/2% chromium and

1% molybdenum, and it meets the other chemical requirements (3).

6.12.1.4 The specification also lists the chemical composition of the weld metal which differs

slightly from the chemical requirements for the wire. The same designations are used for the

weld metal as for the electrode classification in Figure 17 except that the letter “E” is deleted.

For example, the weld metal is designated as A2, B3, Ni2, F2, N3, etc. Since classification of

the composite electrodes is based on the weld metal composition, the letters “EC” are placed

before the weld metal classification and the electrode designation for composite electrodes

would be ECA2, ECB3, ECNi2, etc.

6.12.1.5 An example of a complete flux electrode designation would be as follows:F8P10-ECNi2-Ni2. This designation refers to a flux (F) that will produce weld metal of a

minimum 80,000 psi tensile strength (8), when postweld heat treated (P), and satisfies a

charpy V-notch impact strength test of at least 20 ft.-lbs. at -100°F (10) when used with a

composite electrode (EC) of a nickel type (Ni) containing a nominal 2-1/2% nickel (2) and will

produce weld metal of the chemical composition specified under Ni2 in AWS Specification

A5.23-90 (Ni2).


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LESSON VI

6.13 SPOOLARC LOW ALLOY WIRES FOR SUBMERGED ARC WELDING

6.13.1 Manganese-Molybdenum Wires

6.13.1.1 Spoolarc 40A, 40B, and 40 (AWS Class EA1, EA2, and EA3) - These (Mn-Mo)

wires are designed for pressure vessel fabrication requiring postweld heat treatment and weld

metal tensile strength of 60 ksi, 70 ksi, and 80 ksi. They are generally used with Unionmelt 80,

124, and 429 fluxes.

6.13.2 Chromium-Molybdenum Wires

6.13.2.1 Spoolarc U515 and U521 (AWS Class EB2 and EB3) - Spoolarc U515 and

U521 wires are designed for welding 1-1/4% Cr - 1/2% Mo and 2-1/2% Cr - 1% Mo pressure

vessels. They can be used with Unionmelt 80, 124, and 709-5 fluxes.

6.13.3 Nickel Wire

6.13.3.1 Spoolarc ENi4 (AWS Class ENi4) - Spoolarc ENi4 is designed for single or

multipass welding on high strength steels and produces good low temperature toughness. It is

usable with Unionmelt 429, 439, 709-5, and 656 flux.

6.13.4 High Strength Wires

6.13.4.1 Spoolarc 44 (AWS Class EF2) - Spoolarc 44 is designed for single or multipass

welding on high strength steels of 80 ksi. The addition of nickel helps it produce good low

temperature toughness. It is usable with Unionmelt 709-5 and 656 fluxes.

6.13.4.2 Spoolarc 95, 100, and 120 wires (AWS Class EM2, EM5, and EF4) - Spoolarc

95, 100, and 120 are military grade, high strength, low temperature impact wires designed for

welding HY-80 and HY-100 steels. They are usable with Unionmelt 709-5 and 656 fluxes.

6.13.5 Special Purpose Wires

6.13.5.1 Spoolarc WS (AWS Class EW) - Spoolarc WS is designed for single and multi-

pass welding on weathering grade steels such as A588 and Cor-Ten. The weld chemistry

produces good “color match”, “weathering resistance”, and meets fracture critical code re-

quirements. It is usable with Unionmelt 429, 439, 709-5, and 656 fluxes.


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LESSON VI

6.14 UNIONMELT FLUXES FOR WELDING LOW

ALLOY STEELS6.14.1 Unionmelt 429 Flux - Unionmelt 429 flux is a bonded flux developed for single or

multipass butt and fillet welding on pressure vessel and structural steel fabrication. It operates

on either AC or DC, single or multiple wire operation. It has good performance in the as

welded or stress relieved condition on carbon and low alloy steels.

6.14.2 Unionmelt 439 Flux - Unionmelt 439 flux has similar performance to 429 flux but

will give higher toughness properties.

6.14.3 Unionmelt 656 Flux - Unionmelt 656 operates similar to 439 flux, but has less

tolerance for rust. It should be used on clean material. It will produce excellent low tempera-

ture toughness, better than 439 flux.

6.15 ALLOY SHIELD COMPOSITE ELECTRODES FOR

SUBMERGED ARC WELDING OF THE LOW ALLOY STEELS

6.15.0.1 ESAB produces a line of composite electrodes for welding several varieties of the

low alloy steels. These electrodes carry the brand name Alloy Shield and are used with a

neutral flux since the alloying elements are in the electrode core.

6.15.0.2 Alloy Shield electrodes are available in 3/32" - 5/32" diameters. Each size is

available on 60 lb. coils and for maximum productivity, 500 lb. pay-off packs.

6.15.1 Alloy Shield B1S (No AWS Class) - Alloy Shield B1S is an electrode for welding

the 1/2% Chrome - 1/2% Molybdenum steels. These steels are used principally in power

piping, boiler work and other moderately high temperature applications. Recommended flux isUnionmelt Flux 80. If other fluxes are used, the weld deposit analysis may vary.


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LESSON VI

A. Typical Chemical Analysis of the Weld Metal




Sulfur 0.025%

B. Typical Mechanical Properties of the Weld Metal

Stress Relieved 1 Hr. @1275°F





20 ft.-lbs. @32°F

6.15.2 Alloy Shield B2S (AWS A5.23 F8PZ-ECB2-B2) - Alloy Shield B2S is an electrode

for welding the 1% chromium - 1/2% molybdenum and the 1-1/4% chromium - 1/2% molybde-

num steels for high temperature applications such as power piping, boiler work and tubes,

plate forgings and castings covering a wide variety of ASTM steels. Recommended flux isUnionmelt Flux 80. If other fluxes are used, weld deposit analysis may vary.





Sulfur 0.024%

B. Typical Mechanical Properties of the Weld MetalStress Relieved 1 Hr. @1150°F





16 ft.-lbs. @30°F


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LESSON VI

6.15.3 Alloy Shield B3S (AWS A5.23 F9PZ-ECB3-B3) - Alloy Shield B3S is an electrode

for welding 1% chromium - 1% molybdenum and the 2-1/4% chromium - 1% molybdenum

steels. Used for welding in high strength, high temperature applications, such as power pip-

ing, boiler, and turbine work. Recommended flux is Unionmelt Flux 80. If other fluxes are used,

weld deposit analysis may vary.





Sulfur 0.023%


Stress Relieved 1 Hr. @1275°F





20 ft.-lbs. @32°F

6.15.4 Alloy Shield Ni1S (AWS Class A5.23 F7A6-ECNi1-Ni1) - Alloy Shield Ni1S is an

electrode for nominal 1% Ni weld metal where notch toughness is required in the weld deposit.

Recommended flux is Unionmelt Flux 651VF. If other fluxes are used, weld deposit analysis

may vary.


Carbon 0.06% Sulfur 0.019%

Manganese 1.18% Phosphorus 0.024%

Silicon 0.34% Nickel 0.86%


As Welded





60 ft.-lbs. @-40°F

57 ft.-lbs. @-60°F


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LESSON VI

6.15.5 Alloy Shield Ni2S (AWS 5.23 F8A6, F8P10-ECNi2-Ni2) - Alloy Shield Ni2S is a

nickel alloy electrode for applications where good impact properties are necessary at tem-

peratures as low as -100°F. The weld deposit contains 2-1/2% nickel. Recommended flux isUnionmelt Flux 651VF. If other fluxes are used, weld metal analysis may vary.






As Welded





88 ft.-lbs. @ -40°F 92 ft.-lbs. @ -40°F

65 ft.-lbs. @ -60°F 72 ft.-lbs. @ -60°F

35 ft.-lbs. @-100°F 50 ft.-lbs. @-100°F

6.15.6 Alloy Shield M2S (AWS A5.23 F11A6-ECM2-M2) - Alloy Shield M2S is an elec-

trode for welding the T-1 and other similar high strength steels. Despite its high strength, the

weld metal has good impact properties. Recommended flux is Unionmelt Flux 651VF. If other

fluxes are used, the weld metal analysis may vary.



Manganese 1.6% Nickel 1.83%


Sulfur 0.014%


As Welded




Charpy V-Notch Impacts 62 ft.-lbs. @ 0°F

27 ft.-lbs. @-60°F


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LESSON VI

6.15.7 Alloy Shield M3S (AWS A5.23 F11A4-ECM3-M3) - Alloy Shield M3S is an elec-

trode for welding T-1 and other similar high strength steels requiring tensile strengths of

110,000 to 120,000 psi. It produces good low temperature impacts and is approved by the

American Bureau of Shipping. Recommended flux is Unionmelt Flux 651VF. If other fluxes are

used, the weld metal analysis may vary.





Sulfur 0.017% Molybdenum 0.61%

B. Typical Mechanical Properties of the Weld MetalAs Welded





37 ft.-lbs. @-60°F

6.15.8 Alloy Shield WS (AWS Class A5.23 F7A2-ECW-W) - Alloy Shield WS is for

welding “weathering” grade steels. Weld deposit will color match to the weathering steel after

exposure to the atmosphere. Recommended flux is Unionmelt Flux 651VF. If other fluxes are

used, the weld metal analysis may vary.





Sulfur 0.013% Copper 0.49%


As Welded





32 ft.-lbs. @-20°F


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LESSON VI

6.15.9 Alloy Shield F2S (AWS A5.23 F10P2-ECF2-F2) - Alloy Shield F2S wire devel-

oped for welding SAE 4130 and similar hardenable steels. Retains excellent properties after

stress relieving or quench and tempering. Good choice for oil field equipment requiring less

than 1% nickel. Recommended flux is Unionmelt Flux 709-5. If other fluxes are used, the weld

metal analysis may vary.



Manganese 1.63% Nickel 0.69%


Sulfur 0.012%

B. Typical Mechanical Properties of the Weld MetalStress-Relieved 12 hrs. @1150°F.





35 ft.-lbs. @-20°F

6.15.10 Alloy Shield 420SB (No AWS Class) - Alloy Shield 420SB was specially devel-

oped to match the analysis for continuous caster roll found in the steel making industry. Rec-

ommended flux is Unionmelt Flux S-420SB. If other fluxes are used, the weld metal analysis

may vary.




Silicon 0.20% Chromium 11.70%

B. Hardness of Deposited Weld Metal

1 Layer on 1045 Steel - 54 Rockwell C

2 Layers on 1045 Steel - 51 Rockwell C


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LESSON VI

APPENDIX A

LESSON VI - GLOSSARY OF TERMS

CompositeElectrode

- A filler metal electrode used in arc welding, consisting of more than one metal

component combined mechanically. It may or may not include materials which

protect the molten metal from the atmosphere, improve the properties of the

weld metal or stabilize the arc.

Work Harden - The development of hardness in metals as a result of cold working such as

forming, bending, or drawing.

Anneal - The process of heating a metal to a temperature below the critical range,

followed by a relatively slow cooling cycle to induce softness and remove

stresses.

Deoxidizers - Elements, such as manganese, silicon, aluminum, titanium, and zirconium,

used in welding electrodes and wires to prevent oxygen from forming harmful

oxides and porosity in weld metal.

Flux - Material used to prevent, dissolve, or facilitate removal of oxides and other

undesirable substances in welding, soldering, or brazing. In submerged arc

welding, the flux shields the molten puddle from the atmosphere which helps

to influence the mechanical weld metal deposit.

BondedFluxes

- Bonded fluxes are manufactured by binding an assortment of powder together

and then baking at a low temperature. The major advantage is that addi-

tional alloying ingredients can be added to the mixture.

FusedFluxes

- Fused fluxes are melted ingredients which have been chilled and ground to a

particular particle size. The advantage of this type flux is the low moisture

pick-up and improved recycling capabilities.


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LESSON VI

ActiveFluxes

- Active fluxes produce changes in weld metal chemistry when welding is

changed. Active fluxes are restricted to single or minimal multipass welding.

NeutralFluxes

- Neutral fluxes produce little change to mechanical properties when adjusting

the voltage. Best utilized when welding on plate thickness of one inch or

more.


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BASIC WELDING FILLER METAL

TECHNOLOGY


LESSON VIIFLUX CORED ARC WELDINGELECTRODES FOR CARBON

& LOW ALLOY STEELS


©COPYRIGHT 2000 ESAB WELDING & CUTTING PRODUCTS


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LESSON VIITABLE OF CONTENTSLESSON VII

FLUX CORED ARC WELDING ELECTRODESFOR CARBON & LOW ALLOY STEELS

Part I - Flux Cored Arc Welding Electrodes forCarbon and Low Alloy Steels ............................................................. 1

7.1 INTRODUCTION ................................................................................ 1

7.2 MANUFACTURING FLUX CORED ELECTRODES........................... 1

7.3 FEATURES OF FLUX CORED ELECTRODES ................................. 37.3.1 Functions of the Flux Ingredients ........................................................ 3

7.3.2 Slag Systems ...................................................................................... 4

7.4 GAS SHIELDED TYPES .................................................................. 4

7.4.1 Joint Design ...................................................................................... 4

7.4.2 Shielding Gas ................................................................................... 6

7.4.3 Electrode Extension .......................................................................... 7

7.4.4 All-Position Electrodes ...................................................................... 7

7.4.5 Mild Steel Electrodes ........................................................................ 7

7.4.6 Low Alloy Electrodes ......................................................................... 7

7.5 SELF-SHIELDED ELECTRODES .................................................... 77.5.1 Electrode Extension .......................................................................... 8

7.5.2 All-Position Electrodes ...................................................................... 8

7.5.3 High Deposition Types ...................................................................... 8

7.6 AWS SPECIFICATION A5.20-95 ...................................................... 9

7.6.1 Tensile Strength and Elongation ....................................................... 9

7.6.2 Usability and Performance................................................................ 10

7.6.3 Chemical Composition Requirements .............................................. 10

7.7 INDIVIDUAL ELECTRODE CHARACTERISTICS ........................... 117.7.1 EXXT-1 & EXXT-1M .......................................................................... 11

7.7.2 EXXT-2 ............................................................................................. 12


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7.7.3 EXXT-3 ............................................................................................. 12

7.7.4 EXXT-4 ............................................................................................. 12

7.7.5 EXXT-5 ............................................................................................. 12

7.7.6 EXXT-6 ............................................................................................. 13

7.7.7 EXXT-7 ............................................................................................. 13

7.7.8 EXXT-8 ............................................................................................. 13

7.7.9 EXXT-9 & EXXT-9M ......................................................................... 13

7.7.10 EXXT-10 ........................................................................................... 13

7.7.11 EXXT-11 ........................................................................................... 13

7.7.12 EXXT-12 & EXXT-12M ..................................................................... 13

7.7.13 EXXT-G ............................................................................................ 14

7.7.14 EXXT-GS .......................................................................................... 14

Part II - Individual Dual Shield Flux Cored Wires ForWelding Carbon Steels .................................................................................... 15

7.8 ELECTRODE SELECTION .............................................................. 15

7.9 AWS E70T-1 ELECTRODES ........................................................... 15

7.9.1 DUAL SHIELD ARC 70 ..................................................................... 15

7.9.2 DUAL SHIELD 111A-C ...................................................................... 16

7.9.3 DUAL SHIELD 111HD ....................................................................... 16

7.9.4 DUAL SHIELD R-70 ULTRA ............................................................. 16

7.10 COREWELD METAL CORED WIRES ............................................. 177.10.1 COREWELD 70 ................................................................................ 17

7.10.2 COREWELD ULTRA ........................................................................ 18

7.11 AWS E70T-2 ELECTRODES ........................................................... 187.11.1 DUAL SHIELD 110............................................................................ 19

7.11.2 DUAL SHIELD SP............................................................................. 19

TABLE OF CONTENTSLESSON VII - Con't.


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LESSON VII

7.12 AWS E70T-5 ELECTRODES ........................................................... 207.12.1 DUAL SHIELD T-5 & T-75 ................................................................. 20

7.13 ALL-POSITION ELECTRODES....................................................... 207.13.1 DUAL SHIELD 7000 ......................................................................... 20

7.13.2 DUAL SHIELD 7100 ULTRA ............................................................. 21

7.13.3 DUAL SHIELD FC-717 ..................................................................... 21

7.13.4 DUAL SHIELD II 70 ULTRA & DUAL SHIELD II 71 ULTRA ................ 22

7.14 CORESHIELD SELF-SHIELDED FLUX CORED WIRES .............. 23

7.15 AWS E70T-4 ELECTRODES ........................................................... 237.15.1 CORESHIELD 40 .............................................................................. 23

7.16 AWS E70T-7 ELECTRODES ........................................................... 237.16.1 CORESHIELD 7 ................................................................................ 23

7.17 AWS E70T-10 ELECTRODES ......................................................... 247.17.1 CORESHIELD 10 .............................................................................. 24

7.18 AWS E70T-11 ELECTRODES ......................................................... 247.18.1 CORESHIELD 11 .............................................................................. 24

7.19 AWS E71T-GS ELECTRODES ........................................................ 257.19.1 CORESHIELD 15 .............................................................................. 25

7.20 AWS SPECIFICATION A5.29-80 ...................................................... 25

7.21 AWS DESIGNATIONS...................................................................... 25

7.22 USABILITY AND PERFORMANCE ................................................. 26

7.23 MECHANICAL PROPERTIES REQUIREMENTS ........................... 27

7.24 WELD METAL CHEMICAL COMPOSITION REQUIREMENTS...... 277.24.1 Carbon-Molybdenum ......................................................................... 27

7.24.2 Chromium-Molybdenum ..................................................................... 27

7.24.3 Nickel Steel Electrodes ..................................................................... 28



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7.24.4 Manganese-Molybdenum................................................................... 28

7.24.5 All Other Low Alloy Steel Electrodes .................................................. 29

7.25 IMPACT PROPERTIES .................................................................... 30

7.26 SELECTING THE PROPER LOW ALLOY ELECTRODE ............... 317.26.1 Dissimilar Steels ............................................................................... 31

7.26.2 Welding Procedures .......................................................................... 32

7.27 ADVANCED DEVELOPMENTS IN FLUX CORED ELECTRODES 32

7.28 DUAL SHIELD SELECTOR GUIDE ................................................ 33

APPENDIX A - GLOSSARY OF TERMS ............................................................... 38



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FLUX CORED ARC WELDING ELECTRODESFOR CARBON AND LOW ALLOY STEELS

7.1 INTRODUCTION

Gas shielded flux cored electrodes for welding carbon steels were developed in the early

1950’s and were made commercially available in 1957. This process was developed to

combine the best features of submerged arc welding and CO2 welding. The combination of

the fluxing ingredients in the core and the external CO2 gas shield produce high quality

welds and a stable arc with a low spatter level. Initially, these electrodes were available

only in the larger diameters (5/64"-5/32") and were for use in the flat or horizontal positions

on heavy weldments. In 1972, small diameter gas shielded flux cored electrodes for weld-

ing in all positions were developed, and this greatly expanded the flux cored arc welding

field.

7.1.0.1 Self shielded flux cored electrodes were made available shortly after the gas

shielded types were introduced and both have gained industry wide acceptance for specific

applications. The major differences of the two types were covered in Lesson II and should

be reviewed at this time.

7.2 MANUFACTURING FLUX CORED ELECTRODES

Manufacturing flux cored electrodes requires close controls. Since the weld metal is a

combination of the metal sheath and the flux ingredients, both must be closely checked for

size and chemical composition before fabrication begins.

7.2.0.1 Since the space within the wire is limited, particle size of the ingredients be-

comes very important, so that the particles will “nest” together. Flux ingredients must be

totally mixed or blended and measures taken to prevent segregation of the elements before

fabrication.

7.2.0.2 Most flux cored electrodes are manufactured from a flat metal strip that is passed

through a mill where forming rolls progressively shape it into a U-shaped section. A me-

tered amount of granular flux is fed into the formed strip. It then passes through the closing

rolls, forming the strip into a tube and tightly compressing the core material. See Figure 1.

7.2.0.3 The tube is then pulled through a series of drawing dies that reduce it to its final

size, and further compress the flux to lock it in place within the tube.


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TODRAWING

OPERATIONCLOSINGROLLS

FLUX FILL

FLUXHOPPER

STRIP STEEL

"U" FORMING ROLLS

FLUX CORED ELECTRODE FORMING OPERATIONFIGURE 1

BUTT LAP HEART SHAPED

FLUX CORED ELECTRODE CONFIGURATIONS

FIGURE 2

7.2.0.4 During manufacture, close control to assure that flux voids do not occur through-

out the entire length of the wire is necessary. Also, the surface of the wire must be smooth

and free of contaminants that may be detrimental to feeding and welding current transfer to

the wire. The wire must be carefully wound on spools, coils, or into drums, so that kinks or

bends do not occur. Spools and coils are usually packaged in plastic with some sort of

desiccant material to absorb moisture within the package, and are then placed in a card-

board carton for protection.

7.2.0.5 Flux cored electrodes are manufactured in several different configurations. The

most common are shown in Figure 2. The butt type is used for electrodes where a rela-

tively heavy steel strip is used, and the core ingredients can be lower in volume. Most of

the carbon steel and low alloy steel electrodes of 7/64" diameter and smaller are of this

configuration. Some of the larger diameters and electrodes for the high alloys, such as

stainless steel where it is necessary to include more alloying elements in the core, are of

the lap or heart-shaped configuration.


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7.3 FEATURES OF FLUX CORED ELECTRODES

Flux cored electrodes combine the advantages of several of the welding processes we

have discussed earlier. As with coated electrodes, the flux improves the weld metal chemi-

cal composition and mechanical properties. As in gas metal arc welding and submerged

arc welding, productivity is increased because the electrode is continuous.

7.3.0.1 Flux cored electrodes may be used for welding carbon steels, low alloy high

strength steels, and the high strength quenched and tempered steels. They are also used

for welding stainless steels and abrasion resistant steels. These will be covered in subse-

quent lessons.

7.3.1 Functions of the Flux Ingredients - As with coated ingredients, each manufac-

turer has his own formulas for the flux ingredients. The composition of the flux core can be

varied to provide electrodes for specific applications.

7.3.1.1 The basic functions of the flux ingredients are:

a) Deoxidizers and Denitrifiers - Since nitrogen and oxygen can cause porosity or

brittleness, deoxidizers such as manganese and silicon are added. In the case of

self-shielded electrodes, denitrifiers such as aluminum are added. Both help to

purify the weld metal.

b) Slag Formers - Slag formers such as oxides of calcium, potassium, silicon or so-

dium are added to protect the molten weld puddle from the atmosphere. The slag

aids in improving the weld bead shape and “fast freezing” slags help hold the weld

puddle for out-of-position welding. The slag also retards the cooling rate, especially

important when welding the low alloy steels.

c) Arc Stabilizers - Elements, such as potassium and sodium, help produce a smooth

arc and reduce spatter.

d) Alloying Elements - Alloying elements, such as molybdenum, chromium, carbon,

manganese, nickel, and vanadium, are used to increase strength, ductility, hardness

and toughness.

e) Gasifiers - Minerals, such as fluorspar and limestone, are usually used to form a

shielding gas in the self-shielded type wires.


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7.3.2 Slag Systems - The ingredients in the core determine the weldability of the

electrode and the mechanical properties of the weld metal. Electrodes that have a prepon-

derance of flux components of an acidic nature produce an acid type slag. Those elec-

trodes that are composed of larger amounts of components of a basic nature are said to

produce a basic type slag. Electrodes produced with an acid slag system have excellent

weldability. This means that the arc is smooth and spray-like with very little spatter, and

these electrodes have high operator appeal. The mechanical properties are good and

meet or exceed AWS specifications.

7.3.2.1 Electrodes having a basic slag system produce weld metal with excellent ductility

and notch toughness. The weldability is not as good as that of the acid slag types. Metal

transfer is more globular, resulting in a bit more spatter. Figure 3 shows the characteristics

of the two slag systems.

7.3.2.2 Some low alloy electrodes are now being produced utilizing a recent develop-

ment in slag systems, that combines the excellent weldability of the acid slag types with the

excellent mechanical properties of the basic slag types.

7.4 GAS SHIELDED TYPES

Gas shielded flux cored electrodes are available in diameters of .035" to 1/8" and utilize

reverse polarity (electrode positive) welding current, resulting in high deposition rates, deep

penetration, and a relatively smooth arc. High deposition rates mean that the weld metal

can be deposited more quickly, saving labor and overhead costs, the largest part of the

total welding cost.

7.4.1 Joint Design - Another factor that influences the cost of deposited weld metal is

the joint design. Figure 4 shows the single-vee joints suggested by the American Welding

Society for producing sound welds with the least amount of weld metal for the SMAW and

SLAG MECHANICALSYSTEMS WELDABILITY PROPERTIES

Acid Excellent Good

Basic Fair Excellent

Rutile Basic Excellent Excellent

SLAG SYSTEM CHARACTERISTICS

FIGURE 3


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the FCAW processes. SMAW requires a larger included angle and a considerable root

opening on vee joints, so that the larger diameter of the coated electrode can reach down

into the joint to assure a good root pass. Because of the smaller diameter of the flux cored

electrodes, the included angle may be smaller, and in the case of the CO2 gas shielded

types that have very deep penetration, the required root opening may be very small or in

some cases eliminated. Figure 4 shows the calculated weight of the weld metal per foot of

weld for each joint. The self-shielded flux cored joint requires .337 lbs (13%) less weld

metal than the shielded metal arc joint. The gas shielded flux cored joint requires .970 lbs

(36%) less than the shielded metal arc joint.

7.4.1.1 Comparable savings in the quantity of filler metal can be achieved in fillet welds

made with the gas shielded flux cored process. Conventionally, fillet welds are specified

and measured by the leg length of the largest triangle that can be inscribed in the

cross-section of the weld. The load carrying dimension, the one that determines the

strength of the weld, is the throat dimension. Figure 5A shows a sketch of a typical fillet

weld made with E7018 electrodes. The 1/2" leg weld that results in a throat dimension of

0.35", has a cross-sectional area of 0.125 square inches. This weld requires 0.425 pounds

2.691lbs./ft.

2.354lbs./ft.

1.721lbs./ft.

1/4" 3/8" 3/16"

1" 1" 1"

FLUX CORED ARC WELDING VERSUS SHIELDED METAL ARC WELDINGWEIGHT OF WELD METAL PER FOOT OF JOINT

FIGURE 4

SHIELDED SELF SHIELDED GAS SHIELDEDMETAL ARC FLUX CORED FLUX CORED

.35 THROAT .35 THROAT

1/2 LEG

E7018 GAS SHIELDED FLUXCORED

3/8 LEG

A B

FILLET WELD SIZE COMPARISON - SMAW vs. GAS SHIELDED FCAW

FIGURE 5


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LESSON VII


of filler metal per foot of weld. Figure 5B shows a sketch of a typical fillet weld made with

the flux cored CO2 shielded process. The leg length of this weld measures only 3/8". The

deep penetration of the process results in a throat dimension equal to that in Figure 5A,

0.35". The cross-sectional area of this fillet weld is 0.070 square inches and requires 0.239

pounds of weld metal per foot of weld. This results in a savings of 0.186 pounds per foot of

weld, or a savings of 44% in weld metal volume. It should be remembered that not only is

the cost of the weld metal saved, but also the cost of the labor and overhead that would be

spent in depositing the extra metal. The chart in Figure 6 shows the increase in volume of

weld metal required as the fillet size increases. It shows that if a 5/16" fillet weld is made

where a 1/4" fillet would suffice, more than half (58%) of the amount of weld metal is

wasted.

7.4.2 Shielding Gas - Gas shielded flux cored electrodes require that an adequate

gas shield be present at all times. Gusty or high velocity winds cannot be tolerated and in

such instances, it may be necessary to place a curtain or other wind screen around the

operator. Light breezes will not affect the gas shield. Inadequate gas shielding will be

evidenced by porosity on the surface of the weld metal.

7.4.2.1 CO2 is the most common shielding gas used; however, Argon-CO2 mixtures may

be recommended for some types. The gas shield effectively protects the arc from atmo-

spheric oxygen and nitrogen but some oxygen will be present from the dissociation of the

shielding gas. The deoxidizers in the core materials allow the electrodes to tolerate these

small amounts of oxygen. The need to denitrify the weld metal is of less importance be-

WELD METALFILLET SIZE CU. IN/IN % INCREASE

1/4 .031

58%

5/16 .049

43%

3/8 .070

78.5%

1/2 .125

COST OF OVERWELDING

FIGURE 6


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LESSON VII


cause the shielding gas keeps atmospheric nitrogen from the weld zone. The

manufacturer’s shielding gas recommendation should be followed. Shielding gas flow

rates of 30 to 45 cubic feet per hour are used depending on the electrode size, electrode

extension, and other welding conditions.

7.4.3 Electrode Extension - Electrode extension is the length of an electrode protrud-

ing beyond the end of the contact tip during welding. This dimension is commonly referred

to as “electrical stickout” and is relatively short when using gas shielded flux cored elec-

trodes (3/4" to 1-1/2"). This short electrical stickout with a relatively high welding current

produces narrow, deep penetrating welds.

7.4.4 All-Position Electrodes - Gas shielded, all-position flux cored electrodes con-

tain ingredients in the core that produce a fast freezing slag, and the proper puddle fluidity

for vertical, overhead, or other out-of-position welding. They are available in .045", .052",

and 1/16" diameters. Since the slag helps hold the puddle, the welding voltage and current

may be relatively high, resulting in high deposition rates. The deep penetration of these

electrodes limits the minimum material thickness to 1/8" in the vertical position, and 3/16" in

the flat or horizontal position.

7.4.5 Mild Steel Electrodes - Gas shielded mild steel electrodes are available for

general purpose welding, welding through rust and mill scale of varying degrees,

out-of-position welding, and for applications when high mechanical properties or high

impact values are necessary. Electrodes designed for high deposition rates and high

deposition efficiency are also available. Most of the mild steel electrodes utilize CO2 as the

shielding gas; however, some may use Argon/CO2 mixtures.

7.4.6 Low Alloy Electrodes - Gas shielded flux cored electrodes are widely used for

welding the low alloy, high strength steels. They are available for welding the

carbon-molybdenum, chromium-molybdenum, nickel, manganese-molybdenum and the

high strength quenched and tempered steels. The combination of an external gas shield

and the fluxing elements in the core produce high purity weld metal.

7.5 SELF-SHIELDED ELECTRODES

Self-shielded electrodes rely solely on the materials in the core of the wire for shielding the

arc from the atmosphere, purifying the weld metal and providing the slag formers neces-

sary to protect the molten weld puddle. These electrodes do not rely on gas shielding as

the gas shielded types do; therefore, they can operate more effectively in outdoor environ-

ments without a windscreen.


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LESSON VII


7.5.0.1 Self-shielded electrodes are extensively used in mild steel welding applications.

A few electrodes are available containing 1% nickel for improved strength and impact

properties.

7.5.0.2 Being a continuous welding process, self-shielded electrodes are capable of

higher deposition rates than coated electrodes, and are designed for specific applications

such as general purpose welding, assembly and repair welding, out-of-position welding,

and high deposition welding. Some electrodes are specifically designed for welding lighter

gauge materials (.047" to 3/16" thickness) at high speeds. Self-shielded electrodes are

available in diameters ranging from .030" to 5/32".

7.5.1 Electrode Extension - Self-shielded flux cored electrodes utilize a longer elec-

trode extension than the gas shielded types. The electrode extension ranges from 1/2" to

3-3/4" depending on the electrode type, and the application. The longer length of wire

beyond the contact tip decreases the arc voltage, since the additional wire acts as a resis-

tance. It causes the wire to heat and is accompanied by a lower welding current (amper-

age). This lower voltage and amperage results in a narrow, shallow weld bead that does

not melt as much of the base metal, allowing the process to be used on welding thinner

material and for poor fit-up applications. If the welding current and voltage are increased,

the deposition rate will increase, and to a lesser degree, so will the penetration. It is impor-

tant that the manufacturer’s recommendations for each type and size of electrode are

followed.

7.5.2 All-Position Electrodes - The self-shielded all-position electrodes utilize direct

current, straight polarity (electrode negative). Penetration is low, making them suitable for

bridging gaps in poor fit-up applications. Optimum welding current and amperage settings

are lower than those with the gas shielded types. The .068" and 5/64" diameters are most

commonly used for out-of-position work, although the 3/32" may be used in some cases.

Electrical stickout between 1/2" to 1" is recommended for these wires.

7.5.3 High Deposition Types - The high deposition types of self-shielded wires utilize

long electrical stickout (1-1/2" to 3-3/4") and most use reverse polarity (electrode positive).

Designed for use in the flat or horizontal positions only, they are commonly available in the

5/64", 3/32", 7/64", and .120" diameters.


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LESSON VII



This American Welding Society (AWS) Specification is entitled Specification For CarbonSteel Electrodes For Flux Cored Arc Welding. It prescribes the requirements for classifying

flux cored electrodes for welding carbon steels or low alloy steels.

7.6.0.1 The following requirements will be covered in this text:

1. Whether gas shielded or self-shielded

2. Single pass or multiple pass

3. Type of welding current

4. Welding position

5. As-welded mechanical properties of the weld metal

6. Chemical composition of the weld metal

7.6.0.2 The letter-number designations in this specification are shown in Figure 7.

7.6.0.3 As an example, the designation E71T-1 indicates an electrode (E) that will pro-

duce weld metal of a minimum 72,000 psi ultimate tensile strength (7), may be used for

welding in all positions (1), is a flux cored electrode (T), is a multipass gas shielded type for

operation on direct current, reverse polarity (electrode positive), and must have a minimum

Charpy V-notch value of 20 ft.-lbs at 0°F (Figure 9).

7.6.1 Tensile Strength and Elongation - The specification has only two tensile

strength classifications. They are shown in Figure 8.

Electrode

Min. Tensile Strength X 10,000 psi

0: Flat and Horizontal

1: All Position

T - X

Usability, Performance & Impacts

Tubular or Flux Cored

CARBON STEEL FLUX CORED ELECTRODE DESIGNATIONS

FIGURE 7


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LESSON VII


7.6.2 Usability and Performance - The number of passes, shielding gas require-

ments, type of welding current and the impact requirements, are all specified by the last

digit or letter in the electrode designation. The significance of the last digit or letter is

shown in Figure 9.

TENSILE YIELD* ELONGATION*AWS STRENGTH STRENGTH PERCENT IN

CLASSIFICATION psi. psi. 2 INCHES

E6XT-X 62,000 50,000 22E7XT-X 72,000 60,000 22

* E6XT-GS, E7XT-2, E7XT-3, E7XT-10 and E7XT-GS have no yield strength or elongation requirements.

WELD METAL MECHANICAL PROPERTIES OF CARBON STEELFLUX CORED ELECTRODES

FIGURE 8

7.6.3 Chemical Composition Requirements - The chemical requirements of the weld

metal are specified only for the multipass electrodes, since the single pass types would

show high dilution from the base metal and would be meaningless. Weld metal chemical

composition requirements for the multipass types are:

AWS Classification Shielding Gas Current and Polarity V-notch impact

EXXT-1 Multiple Pass CO2 DCEP 20 ft.-lbs. @0°F*EXXT-1M Multiple Pass 75-80%Ar/bal CO2 DCEP 20 ft.-lbs. @0°F*EXXT-2 Single Pass CO2 DCEP Not SpecifiedEXXT-2M Single Pass 75-80%Ar/bal CO2 DCEP Not SpecifiedEXXT-3 Single Pass None DCEP Not SpecifiedEXXT-4 Multiple Pass None DCEP Not SpecifiedEXXT-5 Multiple Pass CO2 DCEP or DCEN 20 ft.-lbs. @-20°F*EXXT-5M Multiple Pass 75-80%Ar/bal CO2 DCEP or DCEN 20 ft.-lbs. @-20°F*EXXT-6 Multiple Pass None DCEP 20 ft.-lbs. @-20°F*EXXT-7 Multiple Pass None DCEN Not SpecifiedEXXT-8 Multiple Pass None DCEN Not SpecifiedEXXT-9 Multiple Pass CO2 DCEP 20 ft.-lbs. @-20°F*EXXT-9M Multiple Pass 75-80%Ar/bal CO2 DCEP 20 ft.-lbs. @-20°F*EXXT-10 Single Pass None DCEN Not SpecifiedEXXT-11 Multiple Pass None DCEN Not SpecifiedEXXT-12 Multiple Pass CO2 DCEP 20 ft.-lbs. @-20°F*EXXT-12M Multiple Pass 75-80%Ar/bal CO2 DCEP 20 ft.-lbs. @-20°F*EXXT-G Multiple Pass Not Specified Not Specified Not SpecifiedEXXT-GS Single Pass Not Specified Not Specified Not Specified

* "J" Designation indicates V-notch impact values of 20 ft.-lbs. @-40°F

USABILITY, PERFORMANCE AND IMPACT VALUESFLUX CORED ELECTRODE DESIGNATIONS

FIGURE 9


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LESSON VII


Maximum Percent by Weight

(as determined)

E7XT-1; E7XT-1M E7XT-4; E7XT-6E7XT-5; E7XT-5M E7XT-7; E7XT-8

Element E7XT-9; E7XT-9M E7XT-11 E7XT-12; E7XT-12M

Carbon 0.18 Reported 0.15

Manganese 1.75 1.75 1.60

Silicon 0.90 0.60 0.90

Sulfur 0.03 0.03 0.03

Phosphorus 0.03 0.03 0.03

Chromium 0.20* 0.20* 0.20*

Nickel 0.50* 0.50* 0.50*

Molybdenum 0.30* 0.30* 0.30*

Vanadium 0.08* 0.08* 0.08*

Aluminum -- 1.8 --

Copper 0.35 0.35 0.35

* The amounts of these elements shall be reported only if intentionally added.

Single pass types EXXT-2, EXXT-3, EXXT-10 and EXXT-GS have no chemical require-

ments.

7.7 INDIVIDUAL ELECTRODE CHARACTERISTICS

The electrodes in this specification may be grouped by their suffix i.e., T-1, T-2, T-3, etc.,

as having similar flux components that give them similar usability characteristics and are

briefly described here.

7.7.1 EXXT-1 & EXXT-1M - Electrodes of the T-1 classification are gas shielded types,

and the properties required in this specification are listed using CO2 as the shielding gas.

Argon-CO2 gas mixtures may be used for the electrodes specified for all-position welding.These are usually the smaller wires of .045", .052", and 1/16" diameter. Using an

Argon-CO2 gas mixture will diminish the amount of oxygen present and cause the weldmetal to have a higher manganese and silicon content. This will increase the tensile

strength and may improve the impact properties. The manufacturer’s recommendation for

the type of shielding gas should be followed. Those electrodes specified for flat and hori-

zontal fillet welding usually use a CO2 gas shield and will range from 1/16" to 1/8" indiameter.


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LESSON VII


7.7.1.1 These electrodes may be used for single or multiple pass welding. The elec-

trodes in this group have a rutile (acid) slag that is characterized by a spray-like transfer,

little spatter and good weld bead contour that is flat to slightly convex.

7.7.2 EXXT-2 - These electrodes are classified as single pass electrodes because they

contain higher amounts of deoxidizers (manganese and silicon) for welding through rust or

mill scale. Since the rust or mill scale is iron oxide (FeO), the manganese and silicon will

combine with the oxygen in the FeO and float to the slag surface as harmless manganese

oxide or silicon dioxide. If no rust or mill scale is present, or if multiple passes are made

over the preceding passes, the manganese and silicon will become alloying elements in the

weld metal. This can change the mechanical properties drastically, and possibly cause

cracking. These electrodes are for welding in the flat and horizontal positions, and the arc

characteristics and deposition rates are similar to those of the T-1 types. Running one

pass on each side of butt welds can be considered a single pass. There are no chemical

composition requirements for the weld metal produced by these electrodes since it would

be severely diluted with the base metal on single pass welds. They are, however, required

to meet the minimum tensile strength specified in a transverse tensile test as specified in

AWS A5.20-95. These electrodes can be used for welding plate with heavy rust and mill

scale, and still produce X-ray quality welds.

7.7.3 EXXT-3 - These electrodes require no external shielding gas and are for making

high speed, automatic single pass welds on thin material up to 3/16" thickness. Welding

current is DC electrode positive (+). They are for use in the flat and horizontal positions,

and up to 20° downhill welding. These electrodes are limited to 3/16" metal thickness and

single pass welding; otherwise, the welds may become hard and crack sensitive. They

have a spray-like metal transfer.

7.7.4 EXXT-4 - These are self-shielded electrodes designed for high deposition rates,

and they operate on DC electrode positive (+). The metal transfer is globular and the slag

system desulfurizes the weld metal, making it resistant to cracking. Penetration is low,

allowing the weld metal to bridge gaps caused by poor fit-up. These electrodes are for

single or multipass welding in the flat and horizontal positions.

7.7.5 EXXT-5 - These are gas shielded electrodes for flat and horizontal fillet welds.

They have a basic slag system that provides excellent impact properties when compared to

the T-1 and T-2 acid slag types. Spatter level is slightly higher than the T-1 and T-2 elec-

trodes. Argon-CO2 gas mixtures are recommended by some manufacturers for the 1/16"

diameter sizes, for a spray-like metal transfer and high deposition rates. CO2 shielding gasis usually recommended for 5/64" diameters and up, and the metal transfer is more globu-

lar. They may be used for single and multipass welds.


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LESSON VII


7.7.6 EXXT-6 - These self-shielded electrodes operate on direct current, electrode

positive (+). Penetration is relatively good, and the metal transfer is spray-like. Deposition

rate is high, and the weld metal has good low temperature impact properties. They are

used for single and multiple pass welds in the flat and horizontal positions.

7.7.7 EXXT-7 - These are self-shielded electrodes for welding with direct current,

electrode negative (-). The smaller diameters may be used for all-position welding. The

larger diameters, 3/32" and up, produce high deposition rates in the flat and horizontal

positions. The weld metal is relatively crack resistant. These electrodes may be used for

single and multiple pass welding.

7.7.8 EXXT-8 - These are self-shielded electrodes for welding with direct current,

electrode negative (-). They are intended for all-position welding where good impact prop-

erties are necessary. The slag system is such that it desulfurizes the weld metal that helps

to resist cracking. They may be used for single or multiple pass welds.

7.7.9 EXXT-9 & EXXT-9M - Electrodes in the T-9 classification are gas shielded types,

and the properties required in this specification are listed using CO2 as the shielding gas for

EXXT-9 and argon-CO2 gas mixtures for EXXT-9M electrodes. The arc transfer, welding

characteristics, deposition rates and welding parameters will be similar to those electrodes

classified under EXXT-1 and EXXT-1M. Electrodes classified as EXXT-9 and EXXT-9M are

essentially EXXT-1 and EXXT-1M electrodes that deposit weld metal with improved impact

properties, meeting 20 ft.-lbs at -20°F.

7.7.10 EXXT-10 - Electrodes of this classification are self-shielded and operate on

direct current, electrode negative (-). They are single pass electrodes for welding at high

travel speeds in the flat, horizontal, and downhill (up to 20°) position.

7.7.11 EXXT-11 - These electrodes are self-shielded and operate on direct current,

electrode negative (-). They are general purpose electrodes for single and multiple pass

welding in all-positions. The arc is relatively smooth and spray-like.

7.7.12 EXXT-12 & EXXT-12M - These electrodes are essentially EXXT-1 and EXXT-1M

electrodes that have been modified to meet lower manganese requirements of the A-1

Analysis Group in the ASME Boiler & Pressure Vessel Code, Section IX. Therefore, EXXT-

12 and EXXT-12M electrodes will have a decrease in tensile strength and hardness, and

impact properties meeting 20 ft.-lbs at -20°F. The arc transfer, welding characteristics,

deposition rates, and welding parameters will be similar to EXXT-1 and EXXT-1M elec-

trodes.


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LESSON VII


7.7.13 EXXT-G - This classification is for new multipass electrodes that do not fit into

any of the above categories. They may or may not require a gas shield, and their proper-

ties may be any combination of those covered by these specifications.

7.7.14 EXXT-GS - This classification is for new single pass electrodes that do not fit into

any of the above categories. They may or may not require a gas shield, and their proper-

ties may be any combination of those covered by this specification.


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LESSON VII


INDIVIDUAL DUAL SHIELD FLUX CORED WIRESFOR WELDING CARBON STEELS

7.8 ELECTRODE SELECTION

ESAB has a wide variety of flux cored electrodes for welding the mild or medium carbon

steels. For example, there are six electrodes that meet the E70T-1 AWS classification.

Slight formula variations may make one of them more suitable for particular applications

than another. Features such as tensile strength, impact properties, deposition rate, bead

shape and arc characteristics can vary within this group. Another factor in electrode selec-

tion is whether or not the electrode meets the required code or specification for the particu-

lar job.

7.8.0.1 The following is a brief description of each of ESAB’s E70T-1 electrodes cur-

rently available. Only the distinguishing points of each type are covered here to help in

selecting the proper electrode. See the Dual Shield catalog for more complete details and

code or specification approvals.

7.9 AWS E70T-1 ELECTRODES

These electrodes are all multiple pass, CO2 shielded types for DC electrode positive opera-tion. They are for use in the flat and horizontal positions only.

7.9.1 DUAL SHIELD ARC 70 - The very smooth metal transfer produces minimum

spatter and has a very good bead appearance. Slag is easily removed. The plate material

should be reasonably clean.

A. Typical Weld Metal Properties and Chemical Composition

Yield Point 76,700 psi

Tensile Strength 90,200 psi

Elongation in 2" 26%

Charpy V-notch Impact 30 ft-lbs @0°F

Carbon 0.07%

Manganese 1.36%

Silicon 0.65%


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LESSON VII


7.9.2 DUAL SHIELD 111A-C - is one of the most widely used E70T-1 types. The plate

should be reasonably clean, although the relatively high level of deoxidizers will tolerate

some amount of rust or scale. Good spray-like metal transfer with very little spatter. This

electrode has been widely used in fabricating earth moving equipment, bridges, pressure

vessels, construction, shipbuilding and in welds governed by structural, shipbuilding and

nuclear codes and applications. Weld beads are flat to slightly convex.





Reduction of Area 59%


Carbon 0.07%

Manganese 1.45%

Silicon 0.48%

7.9.3 DUAL SHIELD 111HD - This electrode retains good mechanical properties and

operating characteristics of the 111A-C with the added advantage of high deposition rates.

The 3/32" diameter will deposit weld metal at the rate of 18 lbs per hour, at the optimum

parameters of 475 amps, 31 volts. The deposition efficiency is 88-90%. The steel should

be reasonably clean; however, small amounts of rust or scale are tolerable.







Carbon 0.07%

Manganese 1.33%

Silicon 0.58%

7.9.4 DUAL SHIELD R-70 Ultra - A newly reformulated electrode allows for greater

tolerance of mill scale and surface oxides while generating lower welding fumes than other

similar electrodes in the E70T-1 class. The as-welded tensile strength and notch tough-

ness are the highest in this group. The weld bead is smooth and flat. This electrode has

found extensive use in railcar, heavy equipment, and general fabrication.


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LESSON VII








Carbon 0.06%

Manganese 1.60%

Silicon 0.79%

7.10 COREWELD METAL CORED WIRES

Metal cored electrodes are fabricated tubular wires having a metallic sheath with the core

ingredients predominantly iron powder. Iron powder serves to increase the electrodes

deposition efficiency, while improving the speed of travel. Because the slagging ingredients

have been replaced with iron powder, the slag residue makes up less than 5% of the de-

posit. This feature provides the user the capability to multipass without deslagging. These

wires are now classified to AWS A5.18-93.

7.10.1 COREWELD 70 - E70C-6M (.035" - 3/32" diameters). The spray-like transfer

produces deposition rates over 20 lbs/hr. at 90-97% efficiency. It is usable on a variety of

low and carbon steels in a variety of positions. This electrode is ideally suitable for auto-

matic and robotic equipment.


75 Ar/25 CO2 90 Ar/10 CO2

Shielding Shielding

Yield Point 75,500 psi 72,800 psi

Tensile Strength 83,300 psi 86,000 psi

Elongation in 2" 27 28

Charpy V-notch Impacts 40 ft-lbs @0°F 42 ft-lbs @0°F

Carbon 0.034% 0.038%

Manganese 1.250% 1.350%

Silicon 0.750% 0.800%


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LESSON VII


7.10.2 COREWELD ULTRA - E70C-6M (.045" - 1/16" diameters) provides the latest in

technology in production of metal cored wires. Coreweld Ultra provides excellent mechani-

cal properties, smooth spray transfer, low spatter, and extremely low fumes.


75 Ar/25 CO2 92 Ar/8 CO2

Shielding Shielding



Elongation in 2" 28 29


Charpy V-notch Impacts 37 ft-lbs @0°F 31 ft-lbs @0°F

32 ft-lbs @-20°F 28 ft-lbs @-20°F

Carbon 0.030% 0.031%


Silicon 0.62% 0.69%

7.11 AWS E70T-2 ELECTRODES

Electrodes of this classification are all gas shielded for single pass welding, and operate on

direct current reverse polarity (electrode positive). They are considered as single pass

electrodes because the flux contains higher levels of deoxidizers than the T-1 types for

welding on carbon steels with mill scale and rust on the surface. This deoxidation may be

shown by the following reactions:

Mn + FeO MnO + Fe Si + 2FeO SiO2 + Fe

7.11.0.1 The manganese combines with the oxygen to form manganese-oxide that floats

to the surface of the puddle and is harmlessly trapped in the slag. The iron becomes part

of the weld metal. The silicon reaction shows that the silicon reacts with the oxygen in the

rust to form silicon dioxide, which floats to the surface of the puddle and again is trapped in

the slag. The iron becomes part of the weld metal.

7.11.0.2 If used on clean plate, or if used for multiple pass welding where there is no

oxide coating for the manganese and silicon to combine with, these elements become part

of the weld metal. As a result, the tensile strength may increase to over 100,000 psi and

cracking may occur. These electrodes may also be used for welding the rimmed steels

(steels that are not deoxidized).


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LESSON VII


7.11.0.3 Since these are considered single pass electrodes, the AWS Specification does

not require an all-weld metal tensile test because single pass welds would be highly diluted

with the base metal. Instead, the specification only requires a transverse tension test. This

is a 1/4" thick by 1-1/2" wide bar of a minimum 72,000 psi tensile strength material. It is

welded with a single pass on each side of a square butt joint. The welds are ground flush

with the bar, and the specimen is pulled until failure in a tensile testing machine. A speci-

men that breaks in the base plate is considered satisfactory to meet the 72,000 psi mini-

mum.

7.11.0.4 There are no requirements in AWS A5.20-79 for weld metal chemical composi-

tion for the E70T-2 types, since a single pass weld would be highly diluted from the base

plate. We publish the carbon, manganese and silicon content of the undiluted welding

metal for information purposes to indicate the relative amount of the deoxidizers in each

electrode. All of the E70T-2 types require CO2 shielding gas and have no AWS impactrequirements.

7.11.1 DUAL SHIELD 110 - This electrode contains the highest amount of deoxidizers

in the group and is for use on carbon steel plate, that is heavily scaled or rusted. Bead

shape is flat to convex, and the thin slag is easily removed. Meets the 72,000 psi minimum

tensile strength requirements for this classification.

A. Undiluted Weld Metal Analysis (For Information Only)

Carbon 0.07%

Manganese 2.30%

Silicon 1.50%

7.11.2 DUAL SHIELD SP - This electrode contains a lesser amount of deoxidizers than

Dual Shield 110 and is for use on carbon steel plate, that has a considerable amount of mill

scale and rust. The bead contour is very good, and the slag is almost self-removing.

Meets the AWS minimum tensile strength of 72,000 psi.

A. Undiluted Weld Metal Analysis (For Information Only)

Carbon 0.06%

Manganese 1.70%

Silicon 1.25%


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LESSON VII


7.12 AWS E70T-5

7.12.1 DUAL SHIELD T-5 & T-75 - A high quality electrode of the basic slag type. It

produces weld metal of excellent impact properties. The weld metal is resistant to cracking

and the deposition efficiency and deposition rates are high. This electrode has the ap-

proval for use on structural work, heavy equipment, shipbuilding, and military work under

many codes and specifications.

7.12.1.1 CO2 shielding gas is recommended for the 3/32" and 7/64" diameters. Ar-

gon-25% CO2 is recommended for .045" and 1/16" diameters, producing a spray-like

smooth metal transfer. May be used for high current, high deposition welding.

7.13 ALL-POSITION ELECTRODES

ESAB was the originator of gas shielded, all-position flux cored wires. These electrodes

have gained wide usage because they provide the most rapid method of depositing deep

penetrating, sound welds in all positions, thus eliminating costly setup time and expensive

fixturing. Available in .035", .045", .052", and 1/16" diameters, they may be used on plate

thicknesses as thin as 3/16" in the vertical position, and 1/8" in the flat or horizontal. They

have been used for multipass welding on 3" thick material in many nuclear power plant

applications. The shielding gas may be straight CO2 or Argon-25% CO2 as indicated below.

7.13.1 DUAL SHIELD 7000 (E71T-1/E71T-1M & E71T-9/E71T-9M) - This is the original

all-position electrode and was designed to be used with either straight CO2 or Argon-25%

CO2 shielding gas. Using the Argon-CO2 mixture will improve the arc characteristics, in-

crease the wetting action, and decrease penetration slightly. The fast freezing slag is easily

removed and holds the weld puddle for rapid vertical-up and overhead welding. Performs

well over normal mill scale and rust.

A. Typical Weld Metal Mechanical Properties (As Welded)







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LESSON VII


B. Typical Weld Metal Analysis

Carbon 0.06%

Manganese 1.47%

Silicon 0.60%

7.13.2 DUAL SHIELD 7100 ULTRA (E71T-1/E71T-1M & E71T-9/E71T-9M) - This newly

developed electrode is designed for optimum performance with straight CO2 shielding while

generating lower welding fumes. Ar/CO2 mixes up to 75% Ar may be used for better arccharacteristics. Fillet weld beads are flat to slightly convex and have uniform side wall

fusion or wetting. Welds produced are of X-ray quality. This electrode produces a lower

cost per pound of deposited weld metal than any other welding consumable, especially in

the vertical-up and overhead positions.








Carbon 0.06%

Manganese 1.40%

Silicon 0.70%

7.13.3 DUAL SHIELD FC-717 (E71T-1/E71T-1M & E71T-9/E71T-9M) - This all-position

flux cored wire is a lower cost alternative that produces low spatter, smooth stable arc and

a flat to slightly convex bead shape. Shielding gas can be CO2 or Argon/CO2 mixtures up to75% Argon.


CO2 75%Ar/25%CO2

Shielding Shielding



Elongation in 2" 27% 27%

Charpy V-notch Impact 50 ft-lbs @0°F 70 ft-lbs @0°F

30 ft-lbs @-20°F 50 ft-lbs @-20°F


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LESSON VII



CO2 75%Ar/25%CO2

Shielding Shielding

Carbon 0.050% 0.055%


Silicon 0.44% 0.55%

7.13.4 DUAL SHIELD II 70 ULTRA (E71T-1 & E71T-12M) andDUAL SHIELD II 71 ULTRA (E71T-1 & E71T-12)

Dual Shield II 70 Ultra and Dual Shield II 71 Ultra provide all-position welding with excellent

impact toughness and low hydrogen deposits. Arc characteristics are some of the best

found in a flux cored wire with fume generation rates being extremely low. Available in

0.035" to 1/16" diameters, Dual Shield II 70 Ultra and Dual Shield II 71 Ultra are excellent

choices for critical applications.


II 70 Ultra II 71 Ultra



Elongation in 2" 29% 28%

% Reduction in Area 75% 77%

Charpy V-notch Impact 117 ft-lbs @0°F 96 ft-lbs @0°F

70 ft-lbs @-20°F 40 ft-lbs @-20°F


II 70 Ultra II 71 Ultra

Carbon 0.028% 0.019%


Silicon 0.30% 0.30%


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LESSON VII


7.14 CORESHIELD SELF-SHIELDED FLUX CORED WIRES

Self-shielded flux cored wires contain the necessary ingredients within the core to protect

the molten weld metal from atmospheric contaminates. Typically, these products are used

in windy or outdoor environments. Dependent on their specific AWS designation, they are

classed as either single or multipass electrodes. Mechanical properties, especially impact

toughness, is restrictive with the self-shielded electrodes.

7.15 AWS E70T-4

7.15.1 CORESHIELD 40 - This electrode is a self-shielded, horizontal and flat position

weld wire, designed for high deposition welding. The penetration is not as deep as that of

the gas shielded types, making it more suitable for weld joints with poor fit-up.

A. Typical Weld Metal Mechanical Properties




B. Typical Weld Metal Chemical Composition

Carbon 0.22%

Manganese 0.35%

Silicon 0.35%

Aluminum 1.10%

7.16 AWS E70T-7

7.16.1 CORESHIELD 7 - is a multipass wire for flat and horizontal position welding.

This specially developed formulation permits faster travel speeds as compared to

Coreshield 40.

A. Typical Mechanical Properties


Yield Strength 67,000 psi


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LESSON VII


A. Typical Chemical Properties

Carbon 0.26%

Manganese 0.45%

Silicon 0.10%

Aluminum 1.55%

7.17 AWS E70T-10

7.17.1 CORESHIELD 10 - Ideally suited for thin gauge and galvanized steels. This

electrode performs well on high speed, single pass robotic applications.

A. Typical Weld Metal Mechanical Properties

Transverse Tensile Strength 95,900 psi

Longitudinal Guided Bend Test

(Aged 210°F for 48 hrs., bent 180° over 3/4" radius)

7.18 AWS E71T-11

7.18.1 CORESHIELD 11 - is an all-position single or multipass electrode for use in mild

steel applications. The versatility of this electrode makes it an ideal choice for structural

steel applications.


Yield Strength 62,500 - 65,000 psi

Tensile Strength 88,500 - 91,200 psi

Elongation in 2" 22 - 24

A. Typical Weld Metal Composition

Carbon 0.25%

Manganese 0.65%

Silicon 0.40%

Aluminum 1.65%


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LESSON VII


7.19 AWS E71T-GS

7.19.1 CORESHIELD 15 - is an all-position single pass electrode for thin gauge galva-

nized or mild steel application. This electrode is available in .030" - 5/64" diameters.



Longitudinal Guided Bend Passed

A. Typical Chemical Properties

Carbon 0.25%

Manganese 0.70%

Silicon 0.40%

Aluminum 2.40%


This American Welding Society (AWS) Specification is entitled "Specification for LowAlloy Steel Electrodes for Flux Cored Arc Welding". It prescribes the classification

requirements for low alloy steel flux cored electrodes for welding carbon and low alloy

steels. Among the requirements prescribed in the specification are test procedures, wind-

ing requirements, spool and coil standards, packaging standards, and the items listed

below that will be covered in this text.

1. Whether gas shielded or self-shielded

2. Type of welding current

3. Welding position

4. Chemical composition of the weld metal

5. Mechanical properties of the weld metal

7.21 AWS DESIGNATIONS

The letter-number designations used in this specification are shown in Figure 10.

7.21.0.1 As an example, the designation E81T1-Ni2 indicates an electrode (E) that will

produce weld metal of a minimum 80,000 psi tensile strength (8), may be used in welding


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LESSON VII


in all positions (1), is a flux cored electrode (T), is a multipass, gas shielded type for opera-

tion on direct current, electrode positive (1), and will produce weld metal containing ap-

proximately 2% nickel (Ni2).

Electrode

Min. Tensile Strength x 10,000 psi

0: Flat and Horizontal

1: All Position

EXX T X - X

Chemical Composition

Usability and Performance

Tubular or Flux Cored

LOW ALLOY STEEL FLUX CORED ELECTRODE DESIGNATIONS

FIGURE 10

7.22 USABILITY AND PERFORMANCE

The low alloy types have five classifications based on usability and performance. They are

T1, T4, T5, T8, and TX-G. There are two classifications for the gas shielded electrodes,

two classifications for the self-shielded electrodes, and one general classification for new

electrodes that do not fit into any of the categories defined in the A5.29-80 specification.

All of the electrodes in this specification may be used for single or multipass welds. Briefly,

the usability characteristics are:

EXXT1-X CO2 Shielded DC, Electrode Positive

EXXT4-X Self-Shielded DC, Electrode Positive

EXXT5-X CO2 Shielded DC, Electrode Positive

EXXT8-X Self Shielded DC, Electrode Negative

EXXTX-G Not Specified Not Specified

A more complete description of the usability and performance may be found in Section 7.7,INDIVIDUAL ELECTRODE CHARACTERISTICS. They are the same as those specified

for the carbon steel electrodes in Specification A5.20-95.


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LESSON VII


7.23 MECHANICAL PROPERTIES REQUIREMENTS

Figure 11 lists the mechanical property requirements for this specification.

TENSILE MIN. YIELD MIN. PERCENTAWS STRENGTH STRENGTH ELONGATION

CLASSIFICATION psi. psi. IN 2 INCHES

E6XTX-X 60,000 - 80,000 50,000 22E7XTX-X 70,000 - 90,000 58,000 20E8XTX-X 80,000 - 100,000 68,000 19E9XTX-X 90,000 - 110,000 78,000 17

E10XTX-X 100,000 - 120,000 88,000 16E11XTX-X 110,000 - 130,000 98,000 15E12XTX-X 120,000 - 140,000 108,000 14EXXXTX-G As agreed by Manufacturer and Purchaser

For those electrodes using a shielding gas, properties must be attained using CO2.

WELD METAL MECHANICAL PROPERTY REQUIREMENTSLOW ALLOY FLUX CORED ELECTRODES

FIGURE 11

7.24 WELD METAL CHEMICAL COMPOSITION REQUIREMENTS

In this section, we will be referring to the elements by their chemical symbols. The Glos-

sary of Terms at the end of this lesson defines these symbols.

7.24.1 Carbon-Molybdenum Steel Electrodes - The carbon-moly electrodes are used

for moderately high tensile and moderately high temperature applications. Electrodes of

this classification have the suffix A1 (EXXTX-A1). Chemical composition requirements of

the weld metal are listed below and the single figures indicate maximum allowable

amounts.

Element % by Weight Element % by Weight

C 0.12 Mo 0.40 - 0.60

Mn 1.25 P 0.03

Si 0.80 S 0.03

7.24.2 Chromium-Molybdenum Steel Electrodes - The “chrome-moly” types, as they

are commonly referred to, are used in applications requiring strength and resistance to

oxidation (scaling) at elevated temperatures. Their chemical composition requirements are

shown in Figure 12.


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LESSON VII


7.24.3 Nickel Steel Electrodes - The nickel steel electrodes are used for low tempera-

ture applications where good impacts are necessary. As the amount of nickel is increased,

the low temperature impact properties increase. Figure 13 shows the chemical composi-

tion requirements for these electrodes.

AWS Chemical Composition %Class. C Mn Si Cr Mo

EXXTX-B1 0.12 1.25 0.80 0.40 - 0.65 0.40 - 0.65

EXXTX-B2L 0.05 1.25 0.80 1.00 - 1.50 0.40 - 0.65

EXXTX-B2 0.12 1.25 0.80 1.00 - 1.50 0.40 - 0.65

EXXTX-B2H 0.10 - 0.15 1.25 0.80 1.00 - 1.50 0.40 - 0.65

EXXTX-B3L 0.05 1.25 0.80 2.00 - 2.50 0.90 - 1.20EXXTX-B3 0.12 1.25 0.80 2.00 - 2.50 0.90 - 1.20

EXXTX-B3H 0.10 - 0.15 1.25 0.80 2.00 - 2.50 0.90 - 1.20

All Classifications: P - 0.03%, S - 0.03%WELD METAL CHEMICAL COMPOSITION REQUIREMENTSCHROMIUM - MOLYBDENUM FLUX CORED ELECTRODES

FIGURE 12

AWS Chemical Composition %Class. C Mn Si P S Ni Cr Al*

EXXTX-Ni1 0.12 1.50 0.80 0.03 0.03 0.80 - 1.10 0.15 1.8

EXXTX-Ni2 0.12 1.50 0.80 0.03 0.03 1.75 - 2.75 - 1.8EXXTX-Ni3 0.12 1.50 0.80 0.03 0.03 2.75 - 3.75 - -

*Self shielding types only

WELD METAL CHEMICAL COMPOSITION REQUIREMENTS

NICKEL-STEEL FLUX CORED ELECTRODES

FIGURE 13

7.24.4 Manganese-Molybdenum Steel Electrodes - The manganese-moly steels are

used in high strength applications in the 90,000 to 100,000 psi tensile strength range.

Figure 14 shows the chemical composition requirements for these electrodes.

AWS Chemical Composition %Class. C Mn Si Mo P S

EXXT1-D1 0.12 1.25 - 2.00 0.80 0.25 - 0.55 0.03 0.03

EXXT1-D2 0.12 1.65 - 2.25 0.80 0.25 -0.55 0.03 0.03

EXXT1-D3 0.12 1.00 - 1.75 0.80 0.40 - 0.65 0.03 0.03

WELD METAL CHEMICAL COMPOSITION REQUIREMENTSMANGANESE - MOLYBDENUM STEEL FLUX CORED ELECTRODES

FIGURE 14.


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LESSON VII

3.1 Development of Covered Electrodes7.24.5 All Other Low Alloy Steel Electrodes - Low alloy steels that do not fit into any of the previous categories are in this category, with the suffix letter K, G, or W. Notice that in the weld metal chemical composition of the carbon-molybdenum, chromium molybdenum, nickel and manganese-molybdenum steels, only one or two alloyiwere added or changed. In this group, the carbon content is slightly higher, and all of the classifications have varying amounts of manganese, nickel, chromium and molybdenum. Also, vanadium has been added to all but two of the elect 7.24.5.1 The EXXXTX-K category includes electrodes for welding many of the trade name high strength steels, such asUSS T1, HY-80, HY-90, HY-100 and many others. Electrodes for welding the ASTM high strength steels, and the AISI-heat treatable steels are in this group. 7.24.5.2 The W suffix indicates an electrode for welding the weathering grades of steel. These are steels that corrode opoint where te oxide coating becomes impervious to further corrosion. 7.24.5.3 Figure 15 shows the weld metal composition for these electrodes.

(a) single values are maximum only (b) Self-shielded electrodes only (c) Minimum values. The weld metal need have the minimum of only one of the elements listed. Figure 15 Weld Metal Chemical Composition Requirements All Other Alloy Steel Electrodes

AWS Class. Chemical Composition % a

C Mn Si Ni Cr Mo V Alb Cu

EXXTX-K1 0.15 0.80-1.40 0.80 0.80-

1.10 0.15 0.20-0.65 0.05 3/4 3/4

EXXTX-K2 0.15 0.50-1.75 0.80 0.80-

2.00 0.15 0.35 0.05 1.8 3/4

EXXTX-K3 0.15 0.75-2.25 0.80 1.25-

2.60 0.15 0.25-0.65 0.05 3/4 3/4

EXXTX-K4 0.15 1.20-2.25 0.80 1.75-

2.600.20-0.60

0.30-0.65 0.05 3/4 3/4

EXXTX-K5 0.10-0.25

0.60-1.60 0.80 0.75-

2.000.20-0.70

0.15-0.55 0.05 3/4 3/4

EXXTX-K6 0.15 0.50-1.50 0.80 0.40-

1.10 0.15 0.15 0.05 1.8 3/4

EXXTX-K7 0.15 1.00-1.75 0.80 2.00-

2.75 3/4 3/4 3/4 3/4 3/4

EXXTX-KG 3/4 1.0 c 0.80 0.50 c 0.30 c 0.20 c0.10 c 1.8 3/4

EXXTX-W 0.12 0.50-1.30

0.35-0.80

0.40-0.80 3/4 3/4 3/4 3/4 0.30-

0.75


Welding












Electrodes




Filler Metals

LESSON VII


7.25 IMPACT PROPERTIES

The impact properties of the low alloy electrodes are listed in Figure 16.

AWS Impact AWS ImpactClass Strength Class Strength

E80T1-A1 Not Required* E90T5-Ni3 20 ft-lb @ -100° F*E81T1-A1 Not Required* E91T1-D1 20 ft-lb @ -40° F*E70T5-A1 20 ft-lb @ -20° F* E90T5-D2 20 ft-lb @ -60° F*E81T1-B1 Not Required* E100T5-D2 20 ft-lb @ -40° F*E81T1-B2 Not Required* E90T1-D3 20 ft-lb @ -20° F*E80T1-B2 Not Required* E80T5-K1 20 ft-lb @ -40° F*E80T5-B2 Not Required* E70T4-K2 20 ft-lb @ 0° F*E80T1-B2H Not Required* E71T8-K2 20 ft-lb @ -20° F*E80T5-B2L Not Required* E80T1-K2 20 ft-lb @ -20° F*E90T1-B3 Not Required* E90T1-K2 20 ft-lb @ 0° F*E91T1-B3 Not Required* E91T1-K2 20 ft-lb @ 0° F*E90T5-B3 Not Required* E80T5-K2 20 ft-lb @ -20° F*E100T1-B3 Not Required* E90T5-K2 20 ft-lb @ -60° F*E90T1-B3L Not Required* E100T1-K3 20 ft-lb @ 0° F*E90T1-B3H Not Required* E110T1K3 20 ft-lb @ 0° F*E71T8-Ni1 20 ft-lb @ -20° F E100T5-K3 20 ft-lb @ -60° F*E80T1-Ni1 20 ft-lb @ -20° F E110T5-K3 20 ft-lb @ -60° F*E81T1-Ni1 20 ft-lb @ -20° F E110T5-K4 20 ft-lb @ -60° F*E80T5-Ni1 20 ft-lb @ -60° F E111T1-K4 20 ft-lb @ -60° F*R71T8-Ni2 20 ft-lb @ -20° F E120T5-K4 20 ft-lb @ -60° F*E80T1-Ni2 20 ft-lb @ -40° F E120T1-K5 Not RequiredE81T1-Ni2 20 ft-lb @ -40° F E61T8-K6 20 ft-lb @ -20° F*E80T5-Ni2 20 ft-lb @ -75° F E71T8-K6 20 ft-lb @ -20° F*E90T1-Ni2 20 ft-lb @ -40° F E101T1-K7 20 ft-lb @ -60° F*E91T1-Ni2 20 ft-lb @ -40° F E80T1-W 20 ft-lb @ -20° F*E80T5-Ni3 20 ft-lb @ -100° F EXXXTX-G **

* Require post weld heat treatment. All others are as welded.

** As agreed between manufacturer and purchaser.

IMPACT REQUIREMENTS LOW ALLOY STEEL FLUX CORED ELECTRODES

FIGURE 16.

Notice that the impact requirement for the E80T5-Ni1 is 20 ft-lbs at -60°F., while the impact

requirement for the E80T1-Ni1 is 20 ft-lbs at -20°F. The T-5 electrode has a basic slag

system, and the T-1 electrode has an acid slag system. As pointed out earlier, electrodes

with basic slag systems provide improved impact properties; however, they are limited to

flat and horizontal fillet welding only.


Welding












Electrodes




Filler Metals

LESSON VII


7.26 SELECTING THE PROPER LOW ALLOY ELECTRODE

When welding low alloy steels, the tensile strength, yield strength, elongation, and impact

properties of the weld metal should match those of the material being welded as closely as

possible. The chemical composition of the weld metal should match that of the steel also,

although this may not always be possible. The mechanical properties and chemical com-

positions published in the electrode manufacturer’s literature are based on undiluted weld

metal. Welds made on the job will be diluted with the base metal, and composition and

strength level may be somewhat different than the published data. In most cases, how-

ever, matching strength and composition as closely as possible works out well.

7.26.0.1 Choosing an electrode that produces weld metal of slightly greater strength than

the base material is allowable as long as ductility and service requirements are compatible.

In some cases, it may be necessary to use an electrode that produces weld metal of lower

strength than the base metal. This can be beneficial, as long as the strength is sufficient

for the application, since lower strength steels are usually more ductile and less likely to

cause toe-cracking in the base metal. Conversely, gross overmatching of the electrode to

the base material can increase the cracking potential.

7.26.0.2 The wide variety of low alloy steels available today can make electrode selection

a complex problem. In some cases, low alloy steels of the same chemical composition will

have different mechanical properties depending on whether they have been rolled, hot or

cold worked, cast or forged. For this reason, the American Society for Testing Materials

(ASTM) has published several volumes of standards and classifications for the various

forms of ferrous metal products (See Lesson I, "Specifications"). Steel manufacturers and

fabricators assign these classification numbers to their products such as steel sheet, plate,

bar, pipe, castings, forgings, and others. Electrode manufacturers usually provide a list of

some of the more common ASTM specifications for which their electrodes are suited. See

your Atom Arc and Dual Shield catalogs for suggested applications.

7.26.1 Dissimilar Steels - Dissimilar steels with similar metallurgical structure can be

satisfactorily welded with electrodes matching the composition or behavior of the lower

alloys or lower cost electrode. Nothing is gained by using electrodes that match the higher

alloy or higher cost material because the lower composition steel is on one side of the joint

immediately adjacent to the weld metal. As an example, 2-1/4% Cr-1% Mo steel is best

welded to 1-1/4% Cr-1/2 Mo steel with an electrode producing weld metal of 1-1/4% Cr-1/2

Mo composition.


Welding












Electrodes




Filler Metals

LESSON VII


Welding steels of dissimilar metallurgical structure requires a knowledge of welding metal-

lurgy, and when in doubt, the Technical Service Department of the electrode or steel manu-

facturer should be consulted.

7.26.2 Welding Procedures - Procedures for welding the low alloy high strength steels

are more stringent than those used for welding the carbon steels. Preheat, interpass

temperature control and post weld treating are necessary in many cases and will vary

depending on the material thickness. In some cases, hammer peening between passes

may be necessary to relieve stresses and prevent subsequent cracking, or to reduce distor-

tion. Proper joint design and qualified welding procedures for the various alloys must be

adhered to.

7.27 ADVANCED DEVELOPMENTS IN CORED WIRES

Leading the industry in cored wire technology advancements has long been a tradition with

ESAB Welding & Cutting Products. Since they first introduced flux cored wires to the

market in 1957, ESAB has continued to bring innovation to the industry. Consider some of

the advancements in cored wire technology ESAB is proud of introducing:

1957 First flux cored wire introduced

1965 First basic slag flux cored wire introduced for improved mechanical properties

1972 First small diameter, all-position flux cored wire

1984 Dual Shield II Series of Second Generation flux cored wires with good impact

properties and low hydrogen

1985 First .030" diameter flux cored wire introduced

1988 First "Ultra Series" low fume and low spatter flux cored wire introduced

1997 New technology metal cored wire combining excellent weldability with low fume

and exceptional mechanical properties

1998 "H4" Technology flux cored wires

The newest technology innovation is the introduction of the "H4 Technology" flux cored

wires. These wires have the lowest diffusible hydrogen level of any acid slag flux cored

wire, exhibiting less than 4 ml/100 gm weld metal of diffusible hydrogen. "H4 Technology"

cored wires are the Third Generation of a long series of flux cored wire technology ad-

vancements.


Welding












Electrodes




Filler Metals

LESSON VII


DUAL SHIELD® LOW ALLOY FLUX CORED ELECTRODES SELECTOR GUIDE

7.28 DUAL SHIELD SELECTOR GUIDE

The following is a listing of the standard available types of Dual Shield flux cored low alloy

electrodes. For more extensive information, see the ESAB Cored Wire Products catalog.

Dual Shield TypicalType

AWS Class Category As Welded

Stress Relieved

Weld Metal Analysis %

Description-Applications

7000-A1 CO2Tensile Strength, psi 91,000 90,500 C - 0.07

or Yield Strength, psi 80,500 78,500 Mn - 1.02AWS Argon-25% Elongation %-2" 23 24 Si - 0.57

E81T1-A1 CO2Reduction of Area % 58 63 Mo - 0.51

88CM Tensile Strength, psi 106,000 88,000 C - 0.07Yield Strength, psi 94,000 75,000 Mn - 0.74

AWS Elongation %-2" 14 22 Si - 0.34E80T1-B2 Reduction of Area % 29 55 Cr - 1.25

Mo - 0.508000-B1 Argon-25% Tensile Strength, psi 103,700 99,700 C - 0.05

CO2Yield Strength, psi 91,700 86,800 Mn - 0.92

AWS or CO2Elongation %-2" 23 22 Si - 0.56

E81T1-B1 Reduction of Area % 60 64 Cr - 0.52Mo - 0.53

8000-B2 Argon-25% Tensile Strength, psi 104,500 98,000 C - 0.05

CO2Yield Strength, psi 93,000 87,000 Mn - 0.65

AWS or CO2Elongation %-2" 20 21 Si - 0.58

E81T1-B2 Reduction of Area % 53 60 Cr - 1.05

Mo - 0.55T-85-B2 Argon- Tensile Strength, psi 103,000 92,000 C - 0.12

25% CO2Yield Strength, psi 87,000 77,000 Mn - 1.25

AWS Elongation %-2" 23 24 Si - 0.80E80T5-B2 Reduction of Area % 58 67 P - 0.03

Charpy V-Notch 0 F 38 ft-lb 54 ft-lb S - 0.03

Cr - 1-1.5Mo - .40-.65

98-CM CO2Tensile Strength, psi 128,000 96,000 C - 0.06

Yield Strength, psi 109,500 82,500 Mn - 0.70AWS Elongation %-2" 12 20 Si - 0.40


9000-B3 CO2Tensile Strength, psi 120,000 96,000 C - 0.06



Typical Properties Weld Metal

A basic slag electrode for the flat & horizontal positions. Optimum weld quality and resistance to cracking. For welding the low alloy steels up to 1… Cr-‰ Mo. Made in .045" & 1/16" diameters. For high current, high deposition welding.

For flat & horizontal position welding of the 2… Cr-1 Mo steels. Weld metal is similar to E9018-B3 manual electrodes.

An all-position electrode for welding the 2… Cr-1 Mo steels. Suitable for many ASTM specifications such as castings, boiler tubes, forgings and plate for high temperature, high pressure container parts.

For all-position welding of 50,000 psi minimum yield steels and .5% Mo steels. For boilers, pressure vessels, pressure piping and other applications.

For flat and horizontal position welding of the Cr-Mo steels. For welding plates, tubes, castings and forgings.

All-position chrome-moly designed to weld 1/2% chrome - 1/2% moly steels.

An all-position Cr-Mo electrode for welding low alloy steels up to 1‰ Cr-‰ Mo. Similar to E8018-B2 manual electrodes. For welding plate, pipe, tubes, castings or forgings to many ASTM specifications.

Shielding Gas


Welding












Electrodes




Filler Metals

LESSON VII


DUAL SHIELD® LOW ALLOY FLUX CORED ELECTRODES SELECTOR GUIDE (Con't.)


AWS Class CategoryAs

Welded

Stress Relieved

Weld Metal Analysis %

Description-ApplicationsTypical Properties Weld MetalShielding

Gas

T-95-B3 Argon- Tensile Strength, psi 124,000 98,000 C - 0.12

25% CO2 Yield Strength, psi 106,000 82,000 Mn - 1.25AWS Elongation %-2" 20 22 Si - 0.80

E90T5-B3 Reduction of Area % 48 66 Cr - 2-2.5

Charpy V-Notch 0 F 16 ft-lb 31 ft-lb Mo - .9-1.2Coreweld 70 Argon-25% Tensile Strength, psi (75/25) C - 0.039

Ni1 CO2 or Yield Strength, psi 76,400 Mn - 1.21Argon-8% Elongation %-2" 64,200 Si - 0.67

AWS CO2 Reduction of Area % 31 Cr - 0.57

E80C-Ni1 2% O2 Charpy Impacts 72 Ni - 0.67(75/25) (90/10) Cu - 0.59

- 4 F 86.2 85.5 -40 F 40.7 33

88-C3 CO2 Tensile Strength, psi 81,000 78,000 C - 0.06


E80T1-Ni1 Reduction of Area % 60 68 Ni - 1.03Charpy Impact 0 F 50 ft-lb 53 ft-lb -40 F 25 ft-lb 22 ft-lb

Dual Shield II Argon- Tensile Strength, psi 97,000 93,000 C - 0.0580Ni-1 25% CO2 Yield Strength, psi 87,000 82,000 Mn - 1.46

Elongation %-2" 25 26 Si - 0.40AWS Reduction of Area % 65 68 P - 0.02

E81T1-Ni1 Charpy Impact -40 F 61 ft-lb 38 ft-lb S - 0.01

Ni - 0.95

(A-25% CO2 (CO2) (A-25% CO2)8000-Ni2 Argon- Tensile Strength, psi 86,000 84,000 C - 0.05

25% CO2 Yield Strength, psi 74,000 72,000 Mn - 0.95

AWS or CO2 Elongation %-2" 28 28 Si - 0.35E81T1-Ni2 Reduction of Area % 68 67 Ni - 2.60

Charpy Impact 0 F 51 ft-lb 50 ft-lb -20 F 43 ft-lb 43 ft-lb -40 F 30 ft-lb 30 ft-lb

85-C1 CO2 Tensile Strength, psi 85,000 86,500 C - 0.05Yield Strength, psi 71,000 77,000 Mn - 1.17

AWS Elongation %-2" 23 26 Si - 0.30

E80T5-Ni2 Reduction of Area % 56 67 Ni - 2.75Charpy Impact 72 F 59 ft-lb 84 ft-lb

-75 F 41 ft-lb 38 ft-lb

Metal cored wire with 1% addition of nickel alloy. Improved impacts are possible.

A basic slag electrode for the 2… Cr-1 Mo steels. For flat & horizontal position welding only. Optimum weld quality and resistance to cracking. Made in .045" and 1/16" diameters for high current, high deposition welding.

Superior mechanical properties and impacts. A 1% Nickel electrode which exceeds the impacts of most 2% Nickel types. all-position capabilities. Smooth spray transfer. Low nickel analysis well suited for petrochemical applications. Ship building and heavy equipment.

For flat & horizontal fillet positions. A basic slag electrode which produces a 2‰% nickel deposit with excellent low temperature toughness and x-ray quality welds.

Widely used all-position electrode producing 2‰% nickel weld metal. 75% Argon/25% CO2 produces improved weldability. Excellent electrode for ship building and heavy equipment.

For flat and horizontal position welding of the 1% nickel steels. Good impacts at -40 F. Weld metal properties similar to E8018-C3 low hydrogen electrodes.


Welding












Electrodes




Filler Metals

LESSON VII





Welded Stress

RelievedWeld Metal Analysis %


Gas

T-90C1 CO2Tensile Strength, psi 97,500 97,000 C - 0.07


E90T1-Ni2 Reduction of Area % 65 60 Ni - 2.65

Charpy Impact 0 F 35 ft-lb -20 F 27 ft-lb

-50 F 23 ft-lb9000-C1 CO2

Tensile Strength, psi 106,250 102,000 C - 0.05Yield Strength, psi 101,000 93,000 Mn - 1.2

AWS Elongation %-2" 20 24 Si - 0.57E91T1-Ni2 Reduction of Area % 53 61 Ni - 2.30

Charpy Impact -20 F 37 ft-lb 25 ft-lb -40 F 20 ft-lb

9000-D1 CO2Tensile Strength, psi 100,500 101,500 C - 0.09


E91T1-D1 Reduction of Area % 60 58 Mo - 0.45Charpy Impact -20 F 27 ft-lb

150 CO2Tensile Strength, psi 108,500 107,750 C - 0.06


E90T1-D3 Reduction of Area % 30 35 Mo - 0.62Charpy Impact 0 F 37 ft-lb -25 F 30 ft-lb

-50 F 24 ft-lb85NM CO2

Tensile Strength, psi 98,500 85,000 C - 0.07

Yield Strength, psi 89,750 73,500 Mn - 1.09AWS Elongation %-2" 23 26 Si - -0.38

E80T5-K1 Charpy Impact -10 F 60 ft-lb Mo - -0.96

-60 F 34 ft-lb Ni - 0.5098 CO2

Tensile Strength, psi 94,000 95,800 C - 0.07


E90T1-K2 Reduction of Area % 63 61 Mo - 0.20

Charpy Impact 72 F 50 ft-lb 41 ft-lb Ni - 1.75 0 F 38 ft-lb 35 ft-lb

9000M CO2Tensile Strength, psi 103,500 103,000 C - 0.06


E91T1-K2 Reduction of Area % 62 60 Ni - 1.80Charpy Impact 72 F 43 ft-lb 32 ft-lb Mo - 0.25

0 F 30 ft-lb 20 ft-lb

All-position electrode deposits nominal 2% nickel weld metal similar to T-90C1. For welding 2-3% nickel steels and castings requiring good toughness at subzero temperatures.

For flat & horizontal position welding of 2‰%-3 % nickel steels and castings. Good sub-zero toughness.

For all-position welds on 90,000-100,000 psi tensile strength steels. Properties similar to Dual Shield 98.

All-position electrode for nominal 1‰% Mn-‰% Mo steels. For pressure vessel plates and Mn-Mo steel castings.

For flat & horizontal position welding of Mn-Mo steels of 100,000 psi tensile strength.

For flat & horizontal position welding Mn-Mo-Ni steels. Used largely for welding ASTM A533 (grade B) steel for nuclear pressure vessels.

For flat & horizontal position welds 90,000 psi tensile steels. Also for ductile attachment welds on T-1, HY-80, HY-90 & other high strength quenched & tempered steels.


Welding












Electrodes




Filler Metals

LESSON VII





Welded Stress



Gas

T-100 CO2Tensile Strength, psi 104,000 103,000 C - 0.08


E100T1-K3 Reduction of Area % 60 60 Mo - 0.30

Charpy Impact 72 F 45 ft-lb 40 ft-lb Ni - 2.00 -20 F 25 ft-lb 24 ft-lb

-60 F 22 ft-lb 20 ft-lb(HY-80) (Mild Steel)

Dual Shield Argon- Tensile Strength, psi 97,200 94,700 C - 0.058

II 101TM 25% CO2Yield Strength, psi 87,600 86,500 Mn - 1.13

Elongation %-2" 24 24 Si - 0.37

AWS Reduction of Area % 64 64 Ni - 1.78E91T1-K2 Charpy Impacts 0 F 68 79

-60 F 42 49

Dual Shield Argon- Tensile Strength, psi 109,250 110,250 C - 0.05II-100 25% CO2

Yield Strength, psi 101,750 99,300 Mn - 1.40

Elongation %-2" 21 22 Si - 0.38AWS Reduction of Area % 60 61 Cr - 0.02

E100T1-K3 Charpy Impact 0 F 48 ft-lb 33 ft-lb Ni - 1.91

-20 F 40 ft-lb 30 ft-lb Mo - 0.45 -60 F 25 ft-lb 18 ft-lb



E110T1-K3 Reduction of Area % 45 48 Cr - 0.35Charpy Impact 72 F 42 ft-lb 35 ft-lb Ni - 1.85

Mo - 0.45Dual Shield Argon- Tensile Strength, psi 120,400 116,000 C - 0.05

II-110 25% CO2Yield Strength, psi 110,500 108,000 Mn - 1.63

Elongation %-2" 19 19 Si - 0.35AWS Reduction of Area % 54 56 Cr - 0.03

E110T1-K3 Charpy Impact 0 F 40 ft-lb 25 ft-lb Ni - 2.14 -20 F 30 ft-lb 20 ft-lb Mo - 0.46 -60 F 24 ft-lb


(3/32") Argon- Yield Strength, psi 107,000 96,000 Mn - 1.75(.045", 1/16") 25% CO2

Elongation %-2" 24 23 Si - 0.47

Reduction of Area % 65 65 Ni - 2.00AWS Charpy Impact -20 F 50 ft-lb 48 ft-lb Mo - 0.50

-60 F 36 ft-lb 32 ft-lb

All-position flux cored electrode with excellent low temperature impact toughness. Developed specifically for military applications.

Another Dual Shield II electrode with high strength and excellent impact properties. For all-position welding of 110,000 psi steels such as HY-100, T1 and others.

For flat & horizontal welds on 100,000 psi tensile strength steels.

A significant new electrode with high strength and excellent ductility. An all-position electrode for welding the T-1 and HY-80 steels. Excellent low temperature impacts.

For flat & horizontal welds on 110,000 psi steels. For trade name steels such as SSS 100, N-A-XTRA 110, JALLOY S110, USS T1 Type A and others.

For flat & horizontal welds. A basic slag electrode with excellent properties. Small diameters require Argon-CO2 mixture for high current, high deposition welding. For welding T1, HY-80, HY-90, N-A-XTRA 90, 100 & 110 and the SSS 100 steels.


Welding












Electrodes




Filler Metals

LESSON VII





Welded Stress



Gas

T-4130 CO2C - 0.20

Mn - 1.10AWS Si - 0.29

No Spec. Cr - 0.35

Ni - 1.25Mo - 0.22

4130LN Argon- C - 0.22

25% CO2Mn - 1.40

AWS Si - 0.52

No Spec. Cr - 0.56Ni - 0.88

Mo - 0.18

88W CO2Tensile Strength, psi 82,000 84,000 C - 0.05


E80T1-W Reduction of Area % 65.7 56.5 Cr - 0.51Charpy Impact 30 F 66 ft-lb 47 ft-lb Ni - 0.56 0 F 42 ft-lb 35 ft-lb Cu - 0.55

-20 F 32 ft-lb 23 ft-lb -44 F 20 ft-lb 20 ft-lb

Coreweld W Argon- Tensile Strength, psi 92,500 C - 0.031

6% CO2Yield Strength, psi 81,500 Mn - 1.33

AWS Elongation %-2" 26 Si - 0.43

E80C-G Charpy Impacts -20 F 38 Ni - 0.78 -60 F 23.5

8100W CO2Tensile Strength, psi 96,500 C - 0.05

Yield Strength, psi 89,500 Mn - 0.76AWS Elongation %-2" 25 Si - 0.45

E80T1-W Reduction of Area % 61Charpy Impacts 0 F 34

-20 F 31

SEE CATALOG

FOR COMPLETEPROPERTIES

For flat and horizontal position welding of alloys such as A1S1 4130, 8630 and comparable types. The heat treated properties will match those of the base metal.

SEE CATALOG

Metal cored electrode for weathering grade steels such as A588, A242, U.S.S. Cor-Tenfi , and Mayari Rfi .

All-position flux cored electrode to provide color match for weathering grade steels.

FOR COMPLETEPROPERTIES

A basic slag electrode for flat and horizontal welding positions. Resists cracking and welds are of highest quality. For welding SAE 8630 and 4130 heat treatable steels. Low nickel content meets the standards of the National Association of Corrosion Engin

For flat and horizontal position welding of the weathering grade steels such as Cor-Ten or Mayari R.


Welding












Electrodes




Filler Metals

LESSON VII


APPENDIX ALESSON VII - GLOSSARY OF TERMS

Chemical symbols for the alloying elements commonly used in welding metallurgy:

C - Carbon S - SulfurMn - Manganese B - BoronSi - Silicon Al - AluminumCr - Chromium Cb - Columbium (Niobium)Ni - Nickel Ti - Titanium

Mo - Molybdenum W - TungstenV - Vanadium Co - Cobalt

Cu - Copper Pb - LeadP - Phosphorus N - Nitrogen

Flux Voids - Section of a flux cored electrode which contains no flux. Voids can

cause serious problems, especially in low alloy types.

Mill Scale - The iron oxide (FeO) coating normally found on the surface of hot

rolled steels.

- The temperature to which many of the low alloy steels must be

heated before welding. Preheating retards the cooling rate, allowing

more time for the hydrogen to escape, which minimizes underbead

cracking. Preheat temperatures can vary from 10°F to 500°F on ½”

sections to 300°F to 600°F on heavy sections, depending upon the

alloy.

- The minimum temperature of the weldment between passes. It

is usually about the same as the preheat temperature.

Peening - The mechanical working of metal by means of hammer blows to

relieve stresses and reduce distortion. Peening is recommended for

thicker sections (over 1” or 2”) of some alloys on each successive

pass. Experience has shown that peening helps to reduce cracking.

Peening may decrease the ductility and impact properties; however,

the next pass will nullify this condition. For this reason, the last

surface layers should not be peened.

- Reheating the weldment to 1100°F to 1350°F after welding

and holding at that temperature for a specified length of time. Heat

treating allows additional hydrogen to escape, lowers the residual

stresses due to welding, and restores toughness in the heat affected

zone.


Welding












Electrodes



Preheat Temperature


Filler Metals

Interpass Temperature

Post Weld Heat Treatment


TECHNOLOGY


LESSON VIIIHARDSURFACING

ELECTRODES




Welding












Electrodes




Filler Metals


TABLE OF CONTENTSLESSON VIII

HARDSURFACING ELECTRODES


8.1 Introduction to Hardfacing ................................................................... 1

8.1.1 Definition and Purpose ........................................................................ 1

8.1.2 Buildup Alloys ...................................................................................... 2

8.1.3 Hardfacing Alloys ................................................................................. 2

8.1.4 Wear Factors ....................................................................................... 3

8.1.5 Base Metals ......................................................................................... 7

8.2 Classification of Hardfacing Alloys ...................................................... 9

8.2.1 Iron Base Alloys ................................................................................... 9

8.2.2 Nickel Base Alloys ............................................................................... 9

8.2.3 Cobalt Base Alloys .............................................................................. 9

8.2.4 Tungsten Base Alloys .......................................................................... 10

8.3 Methods of Hardfacing ........................................................................ 10

8.3.1 Oxyacetylene Surfacing....................................................................... 11

8.3.2 Shielded Metal Arc Surfacing .............................................................. 11

8.3.3 Gas Tungsten Arc Surfacing ................................................................ 12

8.3.4 Flux Cored Arc Surfacing..................................................................... 12

8.3.5 Submerged Arc surfacing .................................................................... 12

8.3.6 Gas Metal Arc surfacing ...................................................................... 12

8.4 Surfacing With Powders ...................................................................... 13

8.4.1 Flame Spray Process .......................................................................... 13

8.4.2 Manual Torch Process ......................................................................... 13

8.4.3 Plasma Arc Spray and Plasma Arc Welding Process ......................... 13

8.5 General Rules of Hardfacing ............................................................... 14

8.6 Economics of Hardfacing .................................................................... 15


Welding












Electrodes




Filler Metals


TABLE OF CONTENTSLESSON VIII



8.7 ESAB Hardfacing Electrodes .............................................................. 16

8.7.1 Wear-Arc Coated Electrodes............................................................... 16

8.7.2 Wear-O-Matic Open Arc Electrodes .................................................... 16

8.7.3 Wear-O-Matic BR Wires ...................................................................... 16

8.8 Hardfacing Alloy Selection Factors ...................................................... 17

8.8.1 Hardness ............................................................................................. 17

8.8.2 Abrasion and Impact ........................................................................... 18

8.9 Wear-Arc Covered Electrodes and Wear-O-Matic

Wires for Hardfacing ........................................................................... 21

8.9.1 Wear-Arc Covered Electrodes ............................................................. 22

8.9.2 Wear-O-Matic Semiautomatic Cored Wires ........................................ 28

Appendix A Glossary of Terms ....................................................................... 35


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8.1 INTRODUCTION

Hardfacing, or hard surfacing*, has been used as a method of reclaiming industrial partsand equipment since the early 1920’s. At that time, it was found that a hard alloy deposit,

properly applied to the surface of oil drilling bits, extended the life of those bits by more

than ten times. Since then, hardfacing has become universally accepted as an economical

and practical means of restoring plant and field equipment subjected to destructive wear.

8.1.1 Definition and Purpose - Hardfacing may be defined as the application of a

hard, wear resistant alloy to the surface of a softer metal to restore it dimensionally and

reduce wear caused by abrasion, impact, erosion, corrosion and heat.

8.1.1.1 Lubrication of machine parts is an effective method of preventing abrasive wear;

however, in applications such as the external parts of farm and earth moving equipment, oil

drilling tools, engine valves, etc., lubrication is not possible. In these applications,

hardfacing has proven to be an effective means of extending part life by three to eight

times.

8.1.1.2 In many cases, new parts which are destined for destructive wear, are hardfaced

before being put into service initially. Savings are effected by reclaiming worn parts, reduc-

ing maintenance and replacement costs, and permitting the use of relatively inexpensive

base metals.

8.1.1.3 Shops specializing in hardfacing are set up for automatic operation in many

cases. Jigs, fixtures, and rotating devices are often used for economical surfacing of large

numbers of parts. Parts which are large and costly to disassemble, such as power shovel

buckets, can be hardsurfaced on site without dismantling the equipment, using semiauto-

matic or manual arc welding.

8.1.1.4 Various hardfacing and build-up alloys have been designed to perform specific

functions with predictable results. The selection of the proper hardfacing alloys requires a

knowledge of:

1. The wear factors under which it must operate.

2. The function of the part or equipment.

3. The base metal to which it must be applied.(Note: Hardfacing and hard surfacing are synonymous terms.)


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8.1.2 Buildup Alloys - Buildup alloys are used for two purposes. They may serve as a

supporting base for a more wear resistant overlay, or they may serve as a moderately wear

resistant alloy surface when it is necessary to machine the part to size. In some cases, the

buildup alloys may also be used for high strength attachment welds. The selection of the

proper buildup alloy for parts worn beyond practical limits of hardfacing deposits is most

important, since the success of the hardfacing overlay depends upon the rigidity and defor-

mation resistance of the base metal. Experience has proven that in many cases where

hardsurfacing overlays have failed, deformation of the base metal or buildup alloy took

place, causing spalling of the overlay alloy.

8.1.2.1 Badly worn parts should be restored to within 3/16” to ¼” of their original size with

a buildup alloy, which is compatible for welding to the base material and the hardfacing

alloy.

8.1.3 Hardfacing Alloys - Hardfacing alloys are designed to provide maximum wear

resistance to a specific wear factor or a combination of wear factors. Performance of the

overlay is in direct relationship to the amount of carbide forming elements - chromium,

molybdenum, tungsten, vanadium, and iron - in combination with carbon. Wear resisting

carbides are formed when one of these elements is allowed to react with carbon, and as a

result, is completely saturated forming a carbide consisting only of carbon and the element.

The balance of the carbon remains in solution to form a semi-austenitic matrix (bonding

metal) in which the hard, wear resistant carbides are evenly distributed. As the ratio of

wear resistant carbides to alloy matrix increases, abrasion resistance increases. This

same increase reduces the toughness of the overlay, thereby lowering its impact value.

Figure 1 illustrates the effects of the carbide-to-matrix ratio.

VERY HARD CARBIDES

MATRIX

BETTERIMPACT RESISTANCE

BETTERABRASION RESISTANCE

CARBIDES - MATRIX RATIO

FIGURE 1


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8.1.3.1 The pure carbides most commonly used in hardfacing alloys are listed below in order of descending wear resistance. 1. Tungsten Carbide 2. Molybdenum Carbide 3. Chromium Carbide 4. Iron Carbide 8.1.3.2 Tungsten carbide is the hardest of the commercially available carbides within the price structure feasible for hardfacing applications. It provides the maximum resistance to wear, although most hardfacing alloy deposits contain mixtures of two or more of the carbide forming elements. This balanced combination ofcarbides provides a tougher structure, resulting in a more wear resistant deposit. 8.1.4 Wear Factors 8.1.4.1 Impact and Corrosion - These two wear factors can be discussed jointly because the requirements of a hardfacing alloy to combat them are similar. 8.1.4.1.1 Impact occurs when an object is struck by another object. Compression occurs in the form of weightor pressure. The material is said to have good resistance to impact or compressive loads when the yield strength of the material exceeds that of the opposing force. 8.1.4.1.2 Weld metals for hardsurfacing or buildup applications must have the following characteristics to successfully combat wear being caused by impact or compression. 8.1.4.2 Buildup Alloys - When the force of a blow is less than the yield strength of the deposit weld metal, the weld metal absorbs the force with no deformation. When the force of the blow exceeds the yield strength of the deposited weld metal, the weld metal deforms, resulting in roll over or upset.


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8.1.4.3 Hardfacing Alloys - Hardfacing alloys are designed to have very high compres-

sion resistance which usually results in low ductility and low shear strength. See Figure 3.

8.1.4.3.1 Because of these characteristics, hardfacing materials should always be applied

in the manner that allows impact to be absorbed as a compressive force. The term “good

impact resistance” when applied to a hardfacing deposit, means that the deposit will not fail

when impact is born as a compressive force as shown in Figure 4. Hardfacing alloys

should not be applied where only shear forces exist.

PULVERIZING HAMMER

ROLL CRUSHER

POWER SHOVEL TOOTH

These sketches illustrate good examples ofhardfacing applied so that impact is absorbedas a compressive force.

IMPACT AS A COMPRESSIVE FORCE

FIGURE 4

8.1.4.3.2 The base metal over which a hardfacing deposit is to be made must have a high

yield strength to resist deformation. If the base metal has a low yield strength, it upsets

under impact and the hardsurfacing alloy is stressed in tension. As a result, the hardfacing

overlay breaks and spalling occurs as in Figure 5.

HIGHCOMPRESSIONRESISTANCE

LOW DUCTILITY LOW SHEARSTRENGTH

PROPERTIES OF HARDFACING DEPOSIT

FIGURE 3


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8.1.4.4 Abrasion - Abrasive wear occurs when hard particles or objects, such as sand,

stone, or metallic particles, slide or roll over a surface under some amount of pressure. To

scratch, scrape or gouge a surface, the abrasive particles must be harder than the surface

they are in contact with. To prevent this surface damage, hardfacing supplies the logical

harder wear surface, although other factors such as toughness must also be considered.

Abrasion may be considered three general types: scratching, grinding, and gouging.

8.1.4.4.1 Scratching abrasion, or low stress abrasion, is the type of wear caused when the

abrasive particles slide over a surface, such as sand or gravel sliding down the chute, or a

plowshare working in sandy soil. The abrasive particles are not crushed. There are no

large pieces impacting the surface.

8.1.4.4.2 Grinding abrasion, or high stress abrasion, is the wear caused when the abrasive

particles are under a compressive stress sufficient to cause them to be crushed. Cement

plant pulverizer parts and exposed drive sprockets on traced vehicles are examples of high

stress abrasion.

8.1.4.4.3 Gouging abrasion is caused by relatively large sized abrasive pieces which

cause grooves or visible gouges in a surface. Gouging abrasion is usually characterized by

high impact forces. Rock crushing mill hammers and shovel teeth are examples of parts

which are subject to gouging abrasion. In some instances, it may be necessary to sacrifice

some amount of abrasion resistance for better impact properties.

8.1.4.5 Hardness - Although hardness is a desirable factor in combatting wear, it is not a

true criteria of abrasion resistance. As mentioned earlier, those alloys containing a greater

percentage of carbide forming elements will have better abrasion resistance. Hardness, in

relation to abrasion resistance, is illustrated in the deposits of three alloys having equal

matrix hardness, but unequal alloy composition in Figure 6.

HARDFACING

BASE METAL

MECHANICAL FAILURE DUE TO LOW YIELD BASE METAL

FIGURE 5


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8.1.4.5.1 The three examples shown are equal in hardness (Rockwell 50 on the C scale)

but offer increased abrasion resistance as the carbide-to-matrix ratio is increased. As

mentioned in Lesson I, hardness of the metal is tested by measuring its resistance to

indentation. A Rockwell hardness tester produces a relatively large indentation or impres-

sion compared to the microscopic carbides suspended in the matrix, and the penetration

may simply displace the carbide particles. Measurement is more of an indication of the

hardness of the matrix than of the hard particles.

8.1.4.6 Heat - High temperature causes a reduction of wear resistance in metals by

softening, reducing the strength and causing oxidation and scaling. An oxide scale can

actually protect a surface from further oxidation in some cases, although in high tempera-

ture wear applications, the scale is constantly worn away, permitting further rapid oxidation.

Alloys are available which retain their hardness at high temperatures and resist scaling and

oxidation.

8.1.4.7 Corrosion - The corrosion caused by moisture is detrimental to hardfacing alloys

and if salts or acids are present in the water, corrosion will proceed at an accelerated rate.

Many alloys derive some degree of corrosion resistance from a rapidly formed oxide coat-

ing on the surface. However, in an abrasive application, this coating is constantly being

worn away, allowing corrosion to proceed at a rapid rate. By choosing the proper alloy, the

corrosion rate can be minimized.

8.1.4.8 Many hardfacing applications will be subjected to a combination of the wear

factors discussed above. Selecting the proper alloy requires that the wear factors be

analyzed, and the alloy which most closely meets the needs is selected. As a simplified

example, we might consider a back-hoe bucket which is used for digging trenches for

50 Rc 50 Rc 50 Rc

HIGH CARBIDE TOMATRIX RATIO.

MOST ABRASIONRESISTANT.

LOW CARBIDE TOMATRIX RATIO.

LESS ABRASIONRESISTANT.

NO CARBIDES.LEAST ABRASION

RESISTANT.

HARDNESS IN RELATION TO ABRASION RESISTANCE

FIGURE 6


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burying gas lines to homes in an area where the topsoil is a sandy loam, and the sub-soil is

a soft gumbo-like clay. For this application, only abrasion need be considered. If this

back-hoe is moved to work in a new area where the soil contains shale and quartz rock in

small and large pieces, impact and abrasion must be considered.

8.1.5 Base Metals - Basically, there are three types of steel used in the manufacture

of equipment and parts subjected to heavy impact, compressive loads, and abrasive wear.

These are the straight carbon steels, the low alloy high strength steels, and the austen-

itic manganese steels. All of these steels possess good deformation resistance and lend

themselves well to the application of hardfacing alloys if the proper welding procedures are

followed.

8.1.5.1 Carbon Steels - If the base metal is a mild carbon steel with a carbon content of

.20% to .30%, preheat temperatures from 200°F to 300°F are recommended. If the carbon

content of the base metal ranges from .30% to .45%, preheating to 300°F for thin sections,

to 500°F for heavy sections, is necessary. For base metals to .45% to .80% carbon con-

tent, preheat temperatures of 500°F for thin sections, to 800°F for heavy sections, are

necessary. High carbon tool steels containing carbon up to 1.7% are difficult to hardface

because they are prone to cracking. After hardfacing, parts should be allowed to cool

slowly.

8.1.5.2 Low Alloy High Strength Steels - Low alloy steels may be hardfaced as long as

the proper welding procedure is followed. Preheat and postheat temperatures must be

maintained. In some alloys, stress relieving may be necessary. As a rule of thumb, the

welding procedure becomes more critical as the alloy and carbon content increases. Pre-

heat temperatures of 100°F to 600°F are used for most alloys, although some low alloys

with carbon content over .35% require preheat temperatures in the 800°F to 1100°F range.

8.1.5.3 Austenitic Manganese Steel - Austenitic manganese steel (known as Hadfield

steel) is a high alloy containing 11-14% manganese and approximately 1.2% carbon. It is

non-magnetic, unless it has been work-hardened. It is characterized by high strength, high

ductility, and good wear resistance. It has no equal in its ability to work harden. It is widely

used in equipment and parts that are subjected to heavy impact and compressive loads.

These loads actually harden the new surface as the old is slowly worn away. It may actu-

ally have a shorter service life when used in sand where there are no impact loads to work

harden the surface.

8.1.5.4 Unlike carbon and low alloy steels, preheating of high manganese steels is not

recommended. Temperatures above 500°F to 600°F will induce embrittlement if sustained


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LESSON VIII

for long periods of time. The lowest welding current, which produces good fusion with the

base metal, should be used to minimize heat input. Welding in one area for long periods of

time should be avoided. A skip-welding technique should be used. This means that each

succeeding pass should be made as far as possible from the preceding pass.

8.1.5.5 Preheating should only be used when the weldment has been exposed to tem-

peratures below 50°F or when the weldment is massive. Then preheat temperatures of

100°F should not be exceeded.

Type of Steel % CarbonPreheatTemp.

FType of Steel % Carbon

PreheatTemp.

FPLAIN CARBON STEELS NICKEL-CHROMIUM STEELS

Below 0.20 SAE 3115 0.15 200-4000.20-0.30 200-300 SAE 3125 0.25 300-5000.30-0.45 300-500 SAE 3130 0.30 400-7000.45-0.80 500-800 SAE 3140 0.40 500-800

CARBON-MOLYBDENUM STEELS SAE 3150 0.50 600-9000.10-0.20 300-500 SAE 3215 0.15 300-5000.20-0.30 400-600 SAE 3230 0.30 500-7000.30-0.35 500-800 SAE 3240 0.40 700-1000

MANGANESE STEELS SAE 3250 0.50 900-1100

Silicon Structural 0.35 300-500 SAE 3315 0.15 500-700

Medium Manganese 0.20-0.25 300-500 SAE 3325 0.25 900-1100SAE 1330 0.30 400-600 SAE 3435 0.35 900-1100

SAE 1340 0.40 500-800 SAE 3450 0.50 900-1100

SAE 1350 0.50 600-900 LOW CHROMIUM-MOLYBDENUM STEELS12% Manganese (Hadfield)* 1.25 Not Required 2.0% Cr, 0.5% Mo Up to 0.15 400-600

HIGH STRENGTH STEELS 2.0% Cr, 0.5% Mo 0.15-0.25 500-800

Manganese-Molybdenum 0.20 300-500 2.0% Cr, 1.0% Mo Up to 0.15 500-700

Chromium-Copper-Nickel 0.12 max. 200-400 2.0% Cr, 1.0% Mo 0.15-0.25 600-800

Chromium-Manganese 0.40 400-600 MEDIUM CHROMIUM-MOLYBDENUM STEELSNICKEL STEELS 5.0% Cr, 0.5% Mo Up to 0.15 500-800

SAE 2015 0.10-0.20 Up to 300 5.0% Cr, 0.5% Mo 0.15-0.25 600-900

SAE 2115 0.10-0.20 200-300 8.0% Cr, 1.0% Mo 0.15 max. 600-900

Nickel Steel 0.10-0.20 200-400 STAINLESS CHROMIUM STEELSSAE 2315 0.15 200-500 Type 410 300-500 300-500

SAE 2320 0.20 200-500 Type 430 300-500 300-500

SAE 2330 0.30 300-600 Type 446 300-500 300-500

SAE 2340 0.40 400-700 STAINLESS CHROMIUM-NICKEL STEELSMOLYBDENUM STEELS 18-8 Type 304 0.07

SAE 4140 0.40 600-800 25-12 Type 309 0.07 Usually doSAE 4340 0.40 700-900 25-20 Type 310 0.1 not requireSAE 4615 0.15 400-600 18-8 Columbium preheat butSAE 4630 0.30 500-700 Type 347* 0.07 it may beSAE 4640 0.40 600-800 18-8 Molybdenum desirable toSAE 4820 0.20 600-800 Type 316* 0.07 heat to 32 F

18-8 Molybdenum Type 317 0.07

RECOMMENDED PREHEAT TEMPERATURES

FIGURE 7

* When ambient temperature is below 50°F, preheat to 100°F.Interpass temperatures over 500°F should be avoided.


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8.1.5.6 The chart in Figure 7 lists the recommended preheat temperatures for welding

the various grades of steel with the proper welding electrode. In hardfacing, the deposit is

quite different from the base metal and variations dictated by experience may be neces-

sary.

8.2 CLASSIFICATION OF HARDFACING ALLOYS

Unlike the various electrodes, wires and filler metals in the previous lessons, hardfacing

electrodes and filler metals are frequently proprietary alloys made to each manufacturer’s

specifications from formulas proven over the years. Very few of them are classified accord-

ing to an AWS specification. Hardfacing systems may be divided into four basic catego-

ries: iron base, nickel base, cobalt base, and tungsten.

8.2.1 Iron Base Alloys - The iron base alloys as a group are the most widely used of

all the hardfacing systems, and include a wide range of alloy types. These range from low

alloy steels containing 2-12% alloying elements to high alloys containing 12-50% of these

elements. This group includes a number of buildup alloys, as well as excellent hardfacing

alloys. The iron based alloys are characterized by excellent resistance to abrasion in

varying degrees or excellent resistance to impact, depending on alloy content. The higher

alloy versions afford good wear resistant properties up to 1,000°F. Filler metal is available

as coated electrodes, bare electrodes for oxyacetylene welding or gas tungsten-arc weld-

ing, solid or cored wires for submerged arc welding, and cored wires for open arc welding.

8.2.1.1 When surfacing with the high chromium-iron base alloys or other brittle alloys, a

number of small cracks across the weld will appear. These cracks (known as checking or

check cracks) are not detrimental because they do not penetrate into the tougher base

metal or buildup alloy. They are, in fact, helpful in relieving stress buildup which would

cause eventual longitudinal cracking in the fusion zone, leading to spalling of the

hardfacing material. On heavy weldments where heat buildup is great, check cracks may

not appear. They should be induced by a light water spray or by an occasional hammer

blow on the weld surface.

8.2.1.2 The iron base alloys are the lowest in cost of the various hardfacing systems.

8.2.2 Nickel Base Alloys - The nickel base alloys contain 70-80% nickel, 11-17%

chromium, 2.50-3.70% boron, and 0.30-4.50% silicon. The forming of various carbides and

borides in the nickel matrix results in a deposit with excellent resistance to low temperature

abrasion, and makes these the best alloys for metal-to-metal wear. These alloys also have


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LESSON VIII

good heat and corrosion resistance. They retain their hardness and temperatures up to

1200°F. The nickel base alloys lend themselves to flame spray and plasma arc applica-

tions, and are available largely in powder form. The cost of nickel base alloys is approxi-

mately five to six times that of the iron base alloys.

8.2.3 Cobalt Base Alloys - The cobalt base alloys consist of 45-63% cobalt, 24-29%

chromium, 5.50-13.5% tungsten and 1.10-3.20% carbon. They are probably the most

versatile of the hardfacing alloys because they resist heat, corrosion, abrasion, moderate

impacts, galling, and metal-to-metal wear. Some alloys in this group remain substantially

hard at temperatures up to 1500°F. Applications would include hot work equipment such as

hot punches, valve parts, shear blades, etc.

8.2.3.1 In recent years, the price of cobalt has risen sharply since there are few sources

in the world. The price of cobalt alloys per pound exceed that of the iron base alloys by

approximately eighteen times.

8.2.4 Tungsten Base Alloys - The tungsten base alloys produce the most wear resis-

tant deposits of the hard surfacing materials. They consist of hard granules of tungsten

carbide distributed in a matrix of iron, carbon steel, cobalt alloy, or nickel alloy. The matrix,

being somewhat softer than the carbides, wears away to a degree, leaving the hard car-

bides protruding. This roughness of the deposit renders these alloys useless for

metal-to-metal applications, but ideal for applications such as rock drill bits and other min-

ing, quarrying and digging applications.

8.2.4.1 These rods or electrodes are usually supplied as carbon steel tubes filled with

tungsten carbide granules by weight. The steel matrix produced is not soft by any means,

because when the tube melts, it dissolves enough of the tungsten and carbon to form a

hard matrix and is capable of supporting the carbide granules.

8.2.4.2 Despite their excellent abrasion resistance, tungsten carbide alloys can only

withstand impacts that do not produce compressive stress above their yield strength.

Tungsten carbide alloys have low resistance to oxidation and low resistance to corrosion,

unless deposited in a nickel or cobalt matrix. Hardness at high temperatures is approxi-

mately equal to the higher alloy iron base alloys if the tungsten carbide granules are in an

iron or steel matrix. If in a nickel or cobalt matrix, better hot hardness can be achieved.

8.2.4.3 The cost of rods or electrodes consisting of tungsten carbide granules in a car-

bon steel matrix is approximately nine times that of the iron base alloys. If the matrix is a

nickel or cobalt base alloy, costs will be higher.


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8.3 METHODS OF HARDFACING

Hardfacing may be applied by a variety of methods and processes. The method chosen

depends on a number of factors:

a. Size and configuration of the part.

b. End use of the hardfaced part.

c. Depth of overlay required.

d. Quality or smoothness of the overlay.

e. Properties of the deposited overlay.

f. Composition of the base metal.

g. Available forms of the filler metal.

h. Availability of the equipment necessary.

i. Operator skill.

8.3.1 Oxyacetylene Surfacing - The oxyacetylene process, an early method of apply-

ing surfacing alloys, is still in use today. The equipment is low in cost and consists of a

torch, hoses, oxygen cylinder, acetylene cylinder, and two pressure regulators. Unlike

oxyacetylene welding, a thin surface layer of the part in the immediate area being

hardfaced, is brought to melting temperature. The hardfacing alloy is simultaneously

melted into the molten area where it flows and spreads, and is fused to the surface in a thin

smooth layer, with little dilution from the base metal. This method is commonly referred to

as “sweating”.

8.3.1.1 The oxyacetylene process lends itself to servicing small parts, and fills grooves

and recesses well. Other advantages are low dilution and low temperature gradients which

minimize stresses and subsequent cracking. The operator requires much skill, and the

deposition rate is very low. The process does not lend itself to automation, although some

automatic set-ups have been developed.

8.3.2 Shielded Metal Arc Surfacing - SMAW, as described in Lesson II, is a versatile

method of depositing hardfacing materials. The electrode has a flux coating to assure weld

cleanliness. The equipment is the same as for SMAW and consists of a power source,


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LESSON VIII

weld cables, and an electrode holder. Surfacing may be performed in all positions and

although the deposition rate is low, this process is especially useful where many short

welds are to be made. This method is used extensively for field repair and rebuilding of

equipment. The arc power may be either direct or alternating current. Dilution level is

higher than in the oxyacetylene method, but can be kept to a minimum by using the proper

welding current, using a weaving bead instead of a stringer bead and keeping the electrode

in the puddle rather than on the base metal.

8.3.3 Gas Tungsten Arc Surfacing - This process utilizes the same equipment and

procedures as GTAW as discussed in Lesson II. Deposition rate is low, but deposits are of

high quality as long as efforts are made to keep dilution to a minimum. Normal dilution is

somewhat greater than in oxyacetylene surfacing. Although argon, helium or mixtures of

these gases may be used, dilution is the lowest when using pure argon. Gas Tungsten Arc

Surfacing is used for many of the same type of applications as the oxyacetylene process.

These are usually small wear surfaces which require a smooth high quality deposit.

8.3.4 Flux Cored Arc Surfacing - Two types of continuous tubular electrodes are

available for hardsurfacing; self-shielded and those which require a gas shield.

8.3.4.1 The self shielded type are by far the more popular, and in the hardfacing field,

are known as “open arc wires”, indicating that they do not require externally applied granu-

lar flux or shielding gas. Deposits are comparable to those made with coated electrodes,

but there is no stub loss. Since no shielding gas or flux handling equipment are necessary

and the deposition rate is high, it is the most economical process for depositing hardfacing

materials. Portability of the equipment allows this process to be used for hardfacing heavy

equipment in the field, as well as in the shop. Dilution is higher than that of coated elec-

trodes, but lower than that of submerged arc welding.

8.3.4.2 The gas shielded cored wires are used to a lesser extent. The shielding gases

are used to reduce oxidation and minimize alloy loss. The use of CO2 as a shielding gashas a tendency to increase penetration and thereby, increase dilution. Shielding gas and

gas handling equipment also add to the deposition cost.

8.3.5 Submerged Arc Surfacing - Submerged arc welding utilizes both solid and

tubular wires, and a granular flux. It lends itself to automatic operation and is used for

production surfacing of large numbers of parts in shops. The deposition rate and travel

speeds are high, and the penetration is deep. Weld beads are smooth and of good quality.

Heat input is high and for this reason, this process is not recommended for use on austen-

itic manganese steels. The deep penetration causes the highest dilution (up to 50%) of all


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LESSON VIII

of the processes, which makes it necessary to deposit three or more layers to attain the full

properties of the surfacing material.

8.3.6 Gas Metal Arc Surfacing - Gas metal arc surfacing is not widely used for

hardfacing since most of the iron based alloys can be deposited more economically by

other methods. It is used somewhat for out-of-position surfacing where the low penetration

of the short circuiting transfer mode produces low dilution. It is also used for depositing

non-ferrous alloys, such as aluminum-bronze, which cannot be applied by other methods.

8.4 SURFACING WITH POWDERS

The processes previously discussed utilized hardfacing alloys in the form of solid or tubular

rods and wires. Hardfacing alloys are also available in powdered form, and their method of

application is quite different from the standard welding methods. Hardsurfacing powders

are used for restoring worn surfaces and are widely used by original equipment manufac-

turers on new parts which require small hardened surfaces. The four major methods for

applying powder metal hardfacing alloys are: flame spray, manual torch, plasma spray, and

plasma arc welding.

8.4.1 Flame Spray Process - The flame spray process is accomplished with a special

gun-like apparatus which utilizes an oxyacetylene or oxyhydrogen flame. An air orifice

aspirates the powder into the flame and deposits it on the surface. As the molten particles

strike the surface, they flatten out and cool instantaneously. The bond is mechanical since

there is no fusion with the base metal. If desired, fusion can be accomplished in a subse-

quent fusing operation with an oxyacetylene burner.

8.4.1.1 The process is very effective for shafts or small cylindrical parts which are rotated

on a lathe while being surfaced. The surface must be cleaned and grit-blasted before

applying the powder for a good initial bond. Deposition thickness can range from 1/32 to 3/

32 inches.

8.4.2 Manual Torch Process - The manual torch process utilizes a special oxyacety-

lene torch which has a small hopper from which the surfacing powder is aspirated into the

fuel gas stream. Application of the surfacing powder and fusion to the base metal take

place in one operation. Single pass deposit thickness can range from 0.030 to 0.050

inches.

8.4.3 Plasma Arc Spray and Plasma Arc Welding - These are two processes used

to deposit powdered metal surfacing alloys utilizing a plasma arc torch. The plasma arc


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LESSON VIII

torch has a non-consumable tungsten electrode, the end of which is behind a small con-

stricting orifice. The electrode is surrounded by an inert gas such as argon. When the arc

is established, either between the electrode and the constricting nozzle (non-transferred

arc) or between the electrode and the work (transferred arc), the gas becomes ionized in

the arc, forms a plasma, which is forced through the orifice by the plasma gas and im-

pinges on the work piece. In plasma arc spraying, the non-transferred arc torch is used

and the metal powder is introduced into the plasma gas. It is projected at high velocity

against the object being surfaced. Because the metal particles are fully molten and travel

at high velocity, the mechanical bond at the surface is very good and does not require

subsequent fusing in most cases.

8.4.3.1 In plasma arc welding, the transferred arc method is used, which is a higher

energy process. The base metal is actually melted, resulting in a fully fused surface. Both

plasma arc methods lend themselves to high production, automatic surfacing applications

requiring a thin overlay.

8.5 GENERAL RULES FOR HARDFACING

Some general rules and precautions which will help to assure sound hardfacing deposits

are listed below:

a. Base Metal Identification - The base metal must be properly identified so that

the proper buildup and/or hardfacing alloy can be selected. Also, base metal

type will help determine the proper preheat and interpass temperature. A magnet

will help to identify austenitic manganese steel since it is non-magnetic. The

magnet should be tried at several locations on the part because work hardened

areas will be slightly magnetic.

b. Base Metal Preparation - The base metal must be cleaned with a grinding

wheel and be free of rust, oil, grease, or other foreign matter. Cracks, tears, or

gouges must be repaired using the proper filler metal or buildup alloy.

c. Metal Removal - Rolled over and fatigued metal must removed. Work hardened

surfaces of austenitic manganese steel should be ground away before buildup or

surfacing.

d. Buildup - Buildup of badly worn parts to within approximately ¼” of their final

size with an appropriate buildup alloy prior to hardfacing is necessary.


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e. Preheat and Interpass Temperature - The importance of observing preheat and

interpass temperatures cannot be overstressed. Problems, such as spalling,

cracking, and distortion can be minimized by proper preheating, interpass tem-

perature, and slow or retarded cooling.

f. Dilution - Dilution of the hardfacing deposits is expected in all cases where the

hardfacing alloy is fused to the base metal and should be kept to a minimum.

Excessive dilution with the base metal will alter the hardness of the deposit and

in part, is a result of the heat input. Heat input is a function of the heat (amper-

age and voltage) and deposition rate (travel speed).

Note: As an example, a coated electrode, which operates at 225 amps and has a low deposition rate,may put more heat into the workpiece than an open arc continuous electrode, which operates at400 amps but has a deposition rate three times higher than the coated electrode. The electrodemanufacturer’s recommended welding current should be used.

Dilution will be greater in stringer beads (straight) than in a weaving bead. A weaving bead isrecommended wherever possible.

Electrical stickout (the amount of wire between the contact tip and the arc) must be kept relativelyconstant to control penetration in open arc welding. Long stickout decreases penetration andthereby, the amount of dilution. Short stickout can drastically increase penetration and dilution.

g. Hardfacing Thickness - Too much hardfacing can cause more problems than

too little. The hardfacing deposit should consist of no more than two layers and

the total thickness should not exceed ¼” in most cases.

8.6 ECONOMICS OF HARDFACING

Hardfacing filler metals are quite costly as noted earlier. The iron based alloys are the

lowest in cost with the cobalt based alloys being the highest.

8.6.0.1 Consider a steel mill application requiring hardfacing on the guide blocks which

will be subjected to abrasion and intermittent contact with hot billets at temperatures of

approximately 1800-2000°F. Logically, one might choose a cobalt base surfacing alloy,

which will withstand continuously applied higher temperatures than the iron base types for

this application. However, since the guide blocks are in contact with the billets intermit-

tently for short periods of time, the constant operating temperature is well below 800°F.

Iron base hardfacing alloys, which retain hardness at a constant 1000°F, are used in this

application quite successfully at a considerable savings over the cobalt base types.


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LESSON VIII

8.6.0.2 At today’s high labor and overhead rates, the process chosen to apply hardfacing

becomes of more importance. As an example, open arc cored electrodes can deposit

metal three to five times faster than manual electrodes and should be used wherever

possible. The deposition efficiency of the open arc cored electrodes range from 87-95%,

while the deposition efficiency of stick electrodes is only 55-70%, depending on stub loss.

If the cost of the coated hardfacing electrode is $1.00/lb., and the efficiency of that elec-

trode is 60%, the cost of the amount of electrode necessary to deposit 1 lb. of weld metal is

$1.00 ÷ .60 = $1.67. If the cost of an open arc electrode is $1.47/lb., and the deposition

efficiency is 92%, the cost of the amount of electrode necessary to deposit 1 lb. of weld

metal is $1.47 ÷ .92 = $1.60.

8.6.0.3 The “more expensive” open arc wire results in a savings of 7¢ for each pound of

deposited weld metal. When all other factors, such as labor and overhead costs, deposi-

tion rate, and operating factor, are also taken into consideration, savings as high as 60%

can be realized by using open arc continuous electrodes instead of coated electrodes.

8.7 ESAB HARDFACING ELECTRODES

ESAB hardfacing electrodes are all of the iron based alloy type, which is the most widely

used in the industry. They are available as Wear-Arc coated electrodes and as

Wear-O-Matic continuous open arc electrodes.

8.7.1 Wear-Arc Coated Electrodes - Wear-Arc electrodes have a lower hydrogen iron

powder coating. The majority of the materials which are hard surfaced are steels which are

hardened by the heat of welding, and are susceptible to under bead cracking due to hydro-

gen, as covered in Lesson IV. The use of low hydrogen electrodes minimizes this problem.

Proper preheating must still be maintained however; especially on massive parts or highly

restrained joints.

8.7.1.1 As with all low hydrogen types, Wear-Arc electrodes require that they be stored

in a dry rod oven at 225-300°F after the hermetically sealed can is opened.

8.7.1.2 Properly balanced amounts of iron powder are added to these electrodes which

allow higher currents to be used without increasing the penetration and dilution. The higher

welding current results in greater deposition rates. Wear-Arc electrodes allow welding in all

positions.

8.7.2 Wear-O-Matic Open Arc Wires - Wear-O-Matic continuous tubular electrodes

are internally stabilized, fluxed, and deoxidized. They require no shielding gas and repre-

sent the most economical means of reclaiming worn equipment and parts.


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8.7.3 Wear-O-Matic BR Wires - This is a gas shielded tubular, continuous electrode

designed for the repair and reclamation of railroad freight car bolster bowls. It requires a

98% argon, 2% oxygen shielding gas (the full description appears in section 8.9.2.3).

8.8 HARDFACING ALLOY SELECTION FACTORS

In order to select the proper Wear-Arc or Wear-O-Matic alloy, the controlling wear factors

must be determined. Hardness of an overlay deposit is frequently considered as the prime

objective in the selection of a hard surfacing alloy. This might be true if all wear problems

involved only straight abrasive wear. However, most wear conditions are complicated by

the addition of other wear factors which demand more than just hardness of a wear resis-

tant alloy deposit, and the role of alloy content and balance becomes a prime factor. The

importance of alloy content and balance to wear resistance is illustrated in the graphs that

follow. Figure 8 shows the hardness for each Wear-Arc and Wear-O-Matic alloy.

HARDNESS - ROCKWELL "C" SCALE

10 20 30 40 50 60 70 80 90

WEAR-ARC 3IP

WEAR-O-MATIC 3

WEAR-ARC NICKEL MANGANESE

WEAR-O-MATIC NICKEL MANGANESE

WEAR-ARC WH

WEAR-O-MATIC WH

WEAR-ARC 41P

WEAR-ARC 51P

WEAR-ARC 61P

WEAR-O-MATIC 6

WEAR-ARC 12IP

WEAR-O-MATIC 12

WEAR-O-MATIC SUPER WH

WEAR-ARC 40

WEAR-O-MATIC 40

WEAR-O-MATIC 15

WEAR-O-MATIC BR

WEAR-O-MATIC RAIL ARC

HARDNESS COMPARISON

FIGURE 8

AS WELDED

WORK HARDENED


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WEAR-ARC 3IP

WEAR-O-MATIC 3

WEAR-ARC NICKEL MANGANESE

WEAR-O-MATIC NICKEL MANGANESE

WEAR-ARC WH

WEAR-O-MATIC WH

WEAR-ARC 41P

WEAR-ARC 51P

WEAR-ARC 61P

WEAR-O-MATIC 6

WEAR-ARC 12IP

WEAR-O-MATIC 12


WEAR-ARC 40

WEAR-O-MATIC 40

WEAR-O-MATIC 15

RELATIVE RESISTANCE TO IMPACT AND COMPRESSION

FIGURE 9

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8.8.1 Hardness - While constant hardness for various hard surfacing alloys is main-

tained, the particular hardness of any one alloy is a property resulting from the amount of

alloying elements, including carbon, used to create the carbide formations necessary to

attain a desired amount of wear resistance. Succeeding graphs illustrate the importance of

alloy content in relation to hardness in the selection of overlay alloys for resistance to wear

caused by abrasion, impact, compression, and heat.

8.8.1.1 Figure 9 illustrates the relative resistance to impact and compressive force for

each alloy. Note that Wear-O-Matic 15, the hardest of the alloys in Figure 8, shows the

least impact resistance. This is due to the high ratio of carbides to matrix of this alloy which

provide little resistance to shock. Therefore, it is concluded that hardness alone is not a

reliable deciding factor in the choice of hard surfacing alloys.

8.8.1.2 Impact and compression are usually accompanied by other wear factors. In

continuing this comparison of relative wear resistance of the various alloys to different wear

factor combinations, the charts show only those alloys which are practical from an eco-

nomic and application standpoint for the combination of wear factors involved.


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8.8.2 Abrasion & Impact - When abrasion is combined with heavy impact, the alloy

best suited to render the ultimate in wear resistance must have the proper balance of

carbide forming elements in relation to matrix. The alloys shown in Figure 10 have this

structure and are the most suitable buildup and hard surfacing alloys for varying degrees of

impact and abrasion.

8.8.2.1 Although Wear-O-Matic Super WH, Wear-Arc 12 IP, and Wear-O-Matic 12 show

equal resistance to abrasion and impact in Figure 10, Wear-O-Matic Super WH would be

the better choice if more severe impacts are expected. Wear-Arc 12 IP electrodes or

Wear-O-Matic 12 wires for semi-automatic open arc deposition should be used as a wear

resistant overlay in the majority of cases where heavy impact and severe abrasion are in

combination. Wear-Arc 12 IP and Wear-O-Matic 12 provide an abrasion resistant chro-

mium carbide structure, in balance with a highly impact resistant matrix structure, providing

maximum wear resistance throughout the deposited overlay.

8.8.2.2 Wear-Arc WH and Wear-O-Matic WH semi-automatic open arc wire are work

hardening buildup alloys. Their high alloy nickel-chromium-manganese deposit is austen-

itic in structure and can be applied to carbon and austenitic manganese steel in any thick-

ness. Deposits, when subjected to impact, work harden on the skin surface to 48 Rockwell

C and provide wear resistance throughout the buildup deposit equal to that of Wear-Arc 12

and Wear-O-Matic 12.

WEAR-ARC 3IPWEAR-O-MATIC 3

WEAR-ARC NICKEL MANGANESEWEAR-O-MATIC NICKEL MANGANESE

WEAR-ARC WHWEAR-O-MATIC WH




WEAR-ARC 40WEAR-O-MATIC 40

RELATIVE RESISTANCE TO ABRASION AND MEDIUM TO HEAVY IMPACT

FIGURE 10

Buildup Carbon Steel

Best for Overall Buildup - All Conditions

Buildup Manganese Steel Only

Wear-Arc 6IP Best for Out-of-position

Work Hardening Alloy - Severe Impact, Moderate Abrasion

Best for Overall Service - Heavy Impacts and Severe Abrasion

Best for Medium Impact - Extreme Abrasion


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8.8.2.3 Overlaying a buildup deposit of WH alloy with the #12 alloy protects the WH

deposit until it has work hardened.

8.8.2.4 Wear-Arc 6 IP and Wear-O-Matic 6 are illustrated as having good abrasion

resistance under heavy impact loading. Wear-Arc 6 IP electrodes are designed especially

to be used for all-position applications.

8.8.2.5 Figure 11 illustrates the relative wear resistant values of the alloys with the best

abrasion resistance. Wear-O-Matic 15 provides the best resistance to straight abrasion;

however, its impact resistance is low as can be seen in Figure 8. For this reason, Wear-Arc

40 or Wear-O-Matic 40 would be a better choice if medium impacts are involved. Both take

on a high polish and have a low coefficient of friction.

8.8.2.6 Figure 12 illustrates the ability of Wear-Arc 40 and Wear-O-Matic 40 hardfacing

alloys to retain their abrasion resistant properties at constant temperatures up to 1000°F.

Intermittently, temperatures up to 1800°F may be tolerated.

WEAR-ARC 40WEAR-O-MATIC 40

WEAR-O-MATIC 15

RELATIVE RESISTANCE TO STRAIGHT ABRASION

FIGURE 11

DEGREES FARENHEIT

HARDNESS IN RELATION TO TEMPERATURE RISE

FIGURE 12

60Rc

50Rc

40Rc

30Rc

20Rc200 300 400 500 600 700 800 900 1000 1100


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8.8.2.7 Figure 12 also shows that the Wear-Arc WH and Wear-O-Matic WH buildup

alloys will retain their hardness at elevated temperatures. The high chromium and nickel

combination of this alloy imparts excellent high temperature properties and produces an

austenitic work hardening structure.

8.9 WEAR-ARC COVERED ELECTRODES ANDWEAR-O-MATIC WIRES FOR HARDFACING

The following pages contain complete information on each of the individual buildup and

hardfacing alloys supplied by ESAB as they appear in the hardfacing catalog. Each of

them should be studied since several of the test questions will be based on the information

contained on these pages.


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LESSON VIII

8.9.1 Wear-Arc Covered Electrodes

IntroductionSurfacing is the application of wear-resistant alloys to metal parts subject to destructive wear caused by abrasion,impact, compression, heat, or corrosion. The Wear-Arc electrodes are designed for manual arc welding for surfacingparts. Two types of overlay alloys are recommended to correct destructive wear patterns:

Buildup AlloysBecause hardsurfacing alloys are limited by maximum thickness of deposit, badly worn parts must be built up prior todepositing the wear-resistant material. Wear-Arc 3 IP, Nickel Manganese, and WH are designed for buildup applica-tions.These alloys possess good deformation resistance and provide a strong bond with the base metal. This helps toprevent roll-over or spalling and provides a sound base for hardsurfacing.

Hardsurfacing AlloysHardsurfacing alloys are designed to provide maximum resistance to specific wear factors or combination of wearfactors. The performance of these alloys is in direct relation to the amount of carbide forming elements present incombination with carbon. The carbon reacts with the carbide forming elements—chromium, tungsten, molybdenum,etc.—creating hard carbides from which the overlay material derives its wear resistance. These carbides are evenlydistributed in a matrix and as the ratio of carbides to matrix increases, abrasion resistance increases and toughness orductility decreases. The chart below shows the relative impact resistance or “ductility” and the abrasion or wearresistance of the Wear-Arc line.

Relative Resistance to Impact and AbrasionBuildup Alloys Hardsurfacing Alloys

Wear-Arc 3IP Wear-Arc 4 IP

Wear-Arc Nickel Manganese Wear-Arc 5 IP

Wear-Arc WH Wear-Arc 6 IP

Wear-Arc 12 IP

Wear-Arc 40

Impact ResistanceAbrasion Resistance

Welding Currents for Wear-Arc Electrodes

Electrode 3 IP - 4 IP - 5 IP - 6 IP NickelDiameter Flat Vertical Overhead 12 IP Manganese WH 40

1/8" (3.2 mm) 120-160 100-130 120-160 120-160 110-150 130-190 110-1505/32" (4.0 mm) 150-200 120-150 140-190 150-200 140-190 170-250 140-1903/16" (4.8 mm) 200-260 170-200 190-250 200-260 180-240 230-350 190-2501/4" (6.4 mm) 260-320 260-320 230-310 250-310


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8.9.1.1 Wear-Arc 3 IP

No AWS ClassificationAC/DCEP (Electrode Positive)Electrode Imprint Marking: 3 IPBuildup AlloyCarbon SteelsLow Alloy SteelsAbrasion-Resistant SteelsDescription:Wear-Arc 3 IP weld metal provides excellent resistanceto wear caused by heavy impact and compressive loads,and is most suitable as a base alloy for hardsurfacingoverlays.Wear-Arc 3 IP should be used where maximum machin-ability of a surface deposit is desired and as the finaloverlay. The ductility and compressive strength of Wear-Arc 3 IP weld metal is adequate for the wear problem ofmany applications. Typical applications are: steel millwobblers and coupling boxes, bearing journals, steelmill roll necks and ends, forging hammer dies, and allcarbon steel parts requiring buildup prior tohardsurfacing.Procedure:Wear-Arc 3 IP electrodes have superior welding charac-teristics in all positions. Because of the iron powder inthe coating, higher current settings may be used thanwith conventional electrodes.Area Covered per Pound, 1/8" (3.2 mm) Depth—24-25 in.2 (155-161 cm2)Typical Mechanical Properties

As Welded

Yield Strength, psi (MPa) 91,500 (631)Tensile Strength, psi (MPa) 101,750 (702)% Elongation in 2" (51 mm) 24% Reduction in Area 64Hardness 29 Rc**Two Layers weaving on 1020 SteelWeld deposits can be cut with oxy-acetylene torch or by aircarbon-arc cutting.

Typical Undiluted Weld Metal Analysis (%)C Mn Si Cr Mo

0.20 Max. 0.09 0.70 2.30 1.10

Properties of Deposited Weld Metal:The chromium and molybdenum alloy balance impartsimpact and compression resistance, as well as consider-able wear resistance to the weld metal in all thicknessesof buildup. Deposits are machinable, forgeable, andrespond to heat treatment.Standard Diameters and Packages1/8" (3.2 mm) x 10# (4.5 kg) HSC5/32" (4.0 mm) x 10# (4.5 kg) HSC3/16" (4.8 mm) x 10# (4.5 kg) HSC1/4" (6.4 mm) x 10# (4.5 kg) HSC

8.9.1.2 Wear-Arc Nickel Manganese

AWS Class EFeMn-AAC/DCEP (Electrode Positive)Electrode Imprint Marking: Ni MnBuildup AlloyAttachment WeldingManganese SteelSevere ImpactCode and Specification Data:AWS A5.13Description:Wear-Arc Nickel Manganese weld deposit is crackresistant and forms a ductile, high-strength fusion bondon manganese steel. The austenitic structure of the weldprovides excellent resistance to wear caused by heavyimpact and compressive loads. Under conditions ofcontinuous impact, the deposit surface work hardensto a BHN of 510.Wear-Arc Nickel Manganese is best suited for applica-tions where severe impact and compressive forces areencountered continuously. Because of the sound, high-strength welds from this electrode, it should also beused for the attachment welding of wear plates, teeth,rounds, and shapes of manganese steel.Procedure:Wear-Arc Nickel Manganese electrodes require nospecial technique of application. When welding manga-nese steel, these general recommendations should befollowed:1. Weld only on sound, clean, unhardened base metal.2. The use of preheat on manganese steel is not

recommended. Avoid overheating the base metal byusing the lowest current which produces good metaltransfer and arc characteristics. Keep austeniticmanganese steel below 600°F (316°C), interpasstemperature.

Typical Mechanical PropertiesAs Welded

Yield Strength, psi (MPa) 62,000 (427)Tensile Strength, psi (MPa) 116,000 (800)% Elongation in 2" (51 mm) 45Hardness 90 Rb*Work-Hardened Hardness 48 Rc**Two Layers on Manganese SteelWeld deposits can be cut with oxy-acetylene torch or by aircarbon-arc cutting.

Typical Undiluted Weld Metal Analysis (%)C Mn Si Ni

0.60 14.00 0.55 4.00

Standard Diameters and Packages5/32" (4.0 mm) x 10# (4.5 kg) HSC3/16" (4.8 mm) x 10# (4.5 kg) HSC1/4" (6.4 mm) x 10# (4.5 kg) HSC


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LESSON VIII

Typical Mechanical PropertiesWear-Arc 14%

WH ManganeseWeld Metal Steel PlateAs Welded Heat Treated

Yield Strength, psi (MPa) 77,000 (551) 50,000 (345)Tensile Strength, psi (MPa) 97,500 (672) 86,000 (593)

120,000 (827)% Elongation in 2" (51 mm) 36 35/45Hardness 23 Rc* 16 RcWork-Hardened Hardness 48.5 Rc* 48 Rc*Two Layers on 1020 SteelWeld deposits cannot be cut with oxy-acetylene torch or by aircarbon-arc cutting.

Typical Undiluted Weld Metal Analysis (%)C Mn Si Cr Ni

0.45 4.25 0.80 19.75 10.00

8.9.1.3 Wear-Arc WHNo AWS ClassificationAC/DCEP (Electrode Positive)Electrode Imprint Marking: WHBuildup AlloyHigh StrengthManganese & Carbon SteelsAttachment WeldingSevere ImpactDescription:The weld deposit of Wear-Arc WH is high in alloycontent, extremely deformation resistant, and has 2-4times greater wear resistance than work-hardenedaustenitic manganese steel. WH contains approximately34% alloy, properly balanced to perform the dualpurpose of a work-hardening, wear-resistant buildupalloy, and also a high strength welding alloy. The alloy isaustenitic and produces tough, crack-resistant welds.Wear-Arc WH produces a dependable bond to manga-nese steel. Users of type 308, 309, 310, or 312 stainlesssteel electrodes for rebuilding and repair of equipmentconstructed of manganese steel find Wear-Arc WH to bea superior electrode for the job.Deposits of Wear-Arc WH, when subjected to highimpact and compressive loads, develop a surfacehardness of 48-50 Rockwell C and still retain a tough,resilient, deformation-resistant mass under the work-hardened surface.Procedure:Wear-Arc WH electrodes are designed for welding withAC/DCEP (Electrode Positive) in all positions. Whenwelding high-carbon steel, preheat to 300-400°F (149-204°C). Do not preheat manganese steel.Hold the electrode at an angle of 15° in the direction oftravel with as short an arc as possible without allowingthe coating to touch the weld pool. Stringer beads arepreferable. Weaving should be limited to 2-1/2 times theelectrode diameter. Slag should be checked thoroughlybetween passes.For vertical welding, the electrode should be heldperpendicular to the plate using a very slight oscillationfrom side to side on the root bead. When welding in theoverhead position, hold a short arc with no oscillationof the electrode.Area Covered per Pound, 1/8" (3.2 mm)Depth—20-22 in.2 (129-142 cm2)

This chart illustrates a hardness probe of depositedWear-Arc WH weld metal after work-hardening bypeening. Notice that although the outer skin of thedeposit shows a hardness of 48 Rc, the metalunderneath retains the ductility necessary to resistimpact or compressive loads. This toughnessprevents spalling and overroll and provides anexcellent base for harsurfacing overlays.


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8.9.1.5 Wear-Arc 5 IPNo AWS ClassificationAC/DCEP (Electrode Positive)Coded Electrode Marking: 5 IPHardsurfacing AlloyHigh impact and moderate abrasionCarbon steels and low alloy steelsDescription:Wear-Arc 5 IP is an all-position, low hydrogenhardsurfacing composite electrode providing soundoverlays on carbon and low alloy steels, as well asmany abrasion-resistant steels.Wear-Arc 5 IP is recommended for the reclamation ofparts subject to wear caused by moderate to high impactand moderate abrasion. Typical applications are:Dipper ShovelsDipper LipsBulldozer TrunnionsDrag Line Bucket LipsClassifier ScreensBucket PinsMud PumpsBuckets and ImpellersProcedure:Wear-Arc 5 IP electrodes are designed for welding withAC or DCEP. When welding out of position, DCEP ispreferred. A slight weaving technique may be used.Typical Mechanical Properties:Deposits are non-machinable, but may be forged at redtemperatures. The deposit is heat treatable and mag-netic. Weld deposits can be cut with oxy-acetylene torchor by air carbon-arc cutting.Hardness of Deposited Metal:One layer on 1020 mild steel—50-55 Rockwell CTwo layers on 1020 mild steel—58-60 Rockwell CTypical Chemical Analysis of Weld Deposit(%)

C Mn Si Cr Mo

0.65 1.00 0.80 5.75 0.65

8.9.1.4 Wear-Arc 4 IPNo AWS ClassificationAC/DCElectrode Imprint Marking: 4 IPHardsurfacing AlloyMetal-to-Metal WearImpact & AbrasionCarbon Steels & Low Alloy SteelsDescription:Wear-Arc 4 IP is an all position, iron powder, lowhydrogen hardsurfacing electrode providing soundoverlays on carbon and low alloy steels, as well as manyabrasion-resistant steels. The low hydrogen coating ofthis electrode promotes excellent fusion with the abovesteels and on buildup alloys without underbead crack-ing.Wear-Arc 4 IP electrodes are designed to provide hard,deformation-resistant, crack-free weld metal for resis-tance to metal-to-metal wear involving impact,compression, and abrasion. Typical applications are:Dragline bucket pins & links Shovel rollersDredge bucket lips Shovel latch pinsDredge driving tumblers and keepersDredge spud points Tractor idlersCan brake drums Tractor rollersMill brake drums Wheels (Mine car,Shovel idlers skip car, etc.)Cable sheaves Ditcher drive segmentsCable sheave shafts Ditcher rollersElevator bucket lips Shovel boom heelsProcedure:The iron powder, low hydrogen coating of Wear-Arc 4 IPelectrodes provides excellent arc characteristics andhigh deposition rates. A slight weaving technique maybe used. Deposit thickness should be limited to 3/8"(9.5 mm) maximum.Area Covered per Pound, 1/8" (3.2 mm) Depth—24-25 in.2 (155-161 cm.2)

Typical Mechanical Properties:Wear-Arc 4 IP weld metal is characterized by its smoothappearance, high hardness, and high compressivestrength. The deposit is not machinable but may beforged or heat treated. Weld deposits can be cut withoxy-acetylene torch or by air carbon-arc cutting.Hardness of Deposited Metal:Two layers, weave bead on 1020 steel—54-56 Rockwell C.Typical Undiluted Weld Metal Analysis (%)

C Mn Si Cr Mo

0.45 0.90 1.30 2.20 1.00


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8.9.1.7 Wear-Arc 12 IPNo AWS ClassificationAC/DCElectrode Imprint Marking: 12 IPHardsurfacing AlloyHigh Impact & Good Abrasion ResistanceCarbon Steels and Manganese SteelsDescription:In addition to heavy impact and good abrasion resis-tance, the high alloy content of Wear-Arc 12 IP alsoprovides good resistance to erosion and corrosion.Wear-Arc 12 IP is recommended to prolong the servicelife of new and worn parts subject to wear caused byabrasion and impact. Typical applications are:Dipper teeth and lipsDragline bucket lipsConveyor bucket lipsRoll crushersGyratory crusher partsMuller tiresImpactorsHammer mill partsProcedure:The iron powder, low hydrogen coating of Wear-Arc 12IP electrodes provides excellent arc characteristics andhigh deposition rates in all positions using AC or DC,either polarity. Weaving technique or stringer beads maybe used. Deposit thickness should be limited to twopasses or 1/4" (6.4 mm).

Area Covered per Pound, 1/8" (3.2 mm) Depth—22-24 in.2 (142-155 cm.2)Typical Mechanical Properties:Check cracks may appear as the deposit stress relievesitself. These cracks do not impair the wear resistance ofthe deposit, but do prevent warpage or distortion of thebase metal. Deposits are non-machinable and do notrespond to heat treatment. Weld deposits cannot be cutwith oxy-acetylene torch or by air carbon-arc cutting.Hardness of Deposited Metal:Two layers, weave bead on 1020 mild steel—54-56 Rockwell CTypical Undiluted Weld Metal Analysis (%)

C Mn Si Cr Mo

3.50 2.70 1.80 13.00 1.10

8.9.1.6 Wear-Arc 6 IPNo AWS ClassificationAC/DCElectrode Imprint Marking: 6 IPHardsurfacing AlloyHigh Abrasion & Light ImpactCarbon Steels and Manganese SteelsDescription:The iron powder low hydrogen coating of Wear-Arc 6 IPelectrodes promotes good bonds with manganese andcarbon steels.Wear-Arc 6 IP is recommended for the reclamation ofparts subject to wear caused by abrasion and lightimpact. This electrode is ideal for field work where partscannot be positioned for downhand welding. Typicalapplications are:Shovel buckets and teethDragline buckets and teethPug mill paddlesTamping toolsScreensAsphalt mixer paddlesCrushing equipmentGranulatorsTrunnionsTruck bodiesProcedure:The iron powder, low hydrogen coating of Wear-Arc 6 IPelectrodes provides excellent arc characteristics andhigh deposition rates in all positions using AC or DC,either polarity. A weaving technique is recommended.Deposit thickness should be limited to two passes or 1/4" (6.4 mm) maximum.

Area Covered per Pound, 1/8" (3.2 mm) Depth—22-24 in.2 (142-155 cm.2)Typical Mechanical Properties:Deposits are not machinable and are smooth, requiringa minimum amount of grinding to bring them to shape.Deposits are not affected by heat treatment and can beforged at red heat. Weld deposits cannot be cut withoxy-acetylene torch or by air carbon-arc cutting.Hardness of Deposited Metal:Two layers, weave bead on 1020 mild steel—56-59 Rockwell CTypical Undiluted Weld Metal Analysis (%)

C Mn Si Cr

3.00 0.80 1.80 6.50


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Procedure:Wear-Arc 40 electrodes have good welding characteris-tics in flat and vertical-up positions. These electrodesoperate on either AC or DCEP (Electrode Positive)welding current. Weaving technique or stringer beadsmay be used. Limit deposit thickness to two passes.Area Covered per Pound, 1/8" (3.2 mm) Depth—20-24 in.2 (129-155 cm.2)Typical Mechanical Properties:The weld metal deposit of Wear-Arc 40 cannot be forgedat any temperature and does not respond to heattreatment. Weld deposits cannot be cut with oxy-acetylene torch or by air carbon-arc cutting.Hardness of Deposited Metal:Two layers on mild steel—57 Rockwell CTypical Undiluted Weld Metal Analysis (%)

C Mn Si Cr

4.50 0.30 1.80 30.00

8.9.1.8 Wear-Arc 40No AWS ClassificationAC/DCEP (Electrode Positive)Electrode Imprint Marking: 40Hardsurfacing AlloyExtreme Abrasion & Medium ImpactDescription:Wear-Arc 40 is a coated electrode with a special corewire and the proper amount of alloys in the coating toproduce a deposit of highly abrasive resistant chromecarbides in a matrix of iron and chromium. The use of aspecial core wire gives much better arc action and alsoallows the electrode to operate at higher currentsettings. Deposits resist galling and seizing, and take ahigh polish when subject to sliding abrasive action. Thehardness and wear-resistant properties of this alloy areretained at temperatures up to 1000°F (538°C) whichmakes it suitable for many applications where intermit-tent high temperature service is involved.Wear-Arc 40 is designed for use on steel mill twistguides, steel mill entry guides, wire guides, conveyorchain, and agricultural tools. This electrode also givesexcellent service on certain crushing and quarryingequipment where high abrasive wear is the primarywear factor.On many applications where heat and abrasion are theprime wear factors, Wear-Arc 40 alloy may be the mosteconomical alloy. As illustrated in the temperaturehardness chart, this alloy has excellent hardness atconstant temperatures up to about 1000°F (538°C). Inconsidering this alloy for a heat and abrasion applica-tion, a constant operating temperature must beestimated. For example, a steel mill guide block surfacewith Wear-Arc 40 withstands exposure to intermittentcontact with hot billets of bars at temperatures of 1800-2000°F (982-1093°C). This is possible becausesufficient time elapses between contacts to prevent ahigh temperature build-up.In this example, the constant operating temperature isonly about 500°F (260°C).

204 316 427 538 699 760 871

400 600 800 1000 1200 1400 1600Temperature (°C)

Temperature (°F)

Temperature —Hardness

60 Rb100 Rb30 Rc40 Rc50 Rc58 Rc


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LESSON VIII

8.9.2 Wear-O-Matic® Semiautomatic Cored WiresIntroductionThe Wear-O-Matic cored wires for welding, buildup, and hardsurfacing are designed to provide maximum versatility,economy, and welder efficiency in their use. These 7/64" (2.8 mm) diameter wires may be used with either a constantcurrent power source and voltage sensing variable speed wire drive or a constant potential power source and aconstant speed wire feeder. These wires combine the skill of the welder and the speed of automatically fed,continuous wire welding.The variety of electrodes available plus the speed, efficiency, and economy of the Wear-O-Matic process make it themost economical means of reclaiming worn equipment parts.When hard-surfacing with stick electrodes, a minimum of two inches (50 mm) of every 14-inch (350 mm) electrode arethrown away as a stub end. This is a loss of nearly 15% of the total weight of the electrodes purchased by the user.This waste is a major contributing factor toward the low deposition efficiency (55 to 70%) normally obtained with stickelectrodes. The deposition efficiency of the open arc process is usually 87 to 95%.No flux dams are required. Expensive, time consuming flux handling is eliminated, as well as the cost of thesubmerged arc flux.There are no shielding gases that have to be purchased, except for the Wear-O-Matic BR wires. Wires are internallystabilized, fluxed, and deoxidized.High current density and fast travel speed result in low heat input to the work, concentrated in a small area, when usedwith the 7/64" (2.8 mm) alloy wires. There is little slag and no flux blanket to hold heat in the weld area and causeoverheating of the base metal. The total result is low penetration and less dilution of the weld metal. The higher alloydeposits provide increased wear resistance, often superior to deposits of manual electrodes of similar analysis.Most semiautomatic processes (submerged arc, inert gas) have limited use. The simplicity of open arc wire feedequipment makes it extremely portable for field or shop use. All of the visibility and advantages of manual metal arcwelding are preserved. The operator can visually control the deposited metal and irregular contours can be followedeasily.Wear-O-Matic 7/64" (2.8 mm) cored wires for semiautomatic application are fabricated tubular electrodes, internallystabilized for good arc characteristics without the use of shielding gas or submerged arc granular flux. Each of thegrades available has a carefully balanced alloy content to produce specific properties in the deposited weld metal,providing the required wear resistance intended for each grade.

Relative Resistance to Impact and AbrasionBuildup Alloys Hardsurfacing Alloys

Wear-O-Matic 3 Wear-O-Matic 6

Wear-O-Matic Wear-O-Matic 12 Nickel Manganese

Wear-O-Matic WH Wear-O-Matic Super WH

Wear-O-Matic BolsterRepair Wear-O-Matic 40

Wear-O-Matic 15

Impact ResistanceAbrasion Resistance


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LESSON VIII

8.9.2.2 Wear-O-Matic NickelManganeseNo AWS ClassificationDCEP (Electrode Positive)Open Arc—Buildup AlloyAttachment WeldingManganese SteelDescription:Wear-O-Matic Nickel Manganese—7/64" (2.8 mm)diameter alloy wire for open arc, semiautomatic applica-tion provides the necessary high tensile and yieldstrength to permit this alloy to be used for both attach-ment welding and buildup applications on austeniticmanganese steel. The weld metal has excellent ductilityand provides an ideal base for subsequenthardsurfacing overlays.Wear-O-Matic Nickel Manganese open arc wires arerecommended for the rebuilding and high strengthwelding of austenitic manganese steel parts and equipment.

Procedure:Wear-O-Matic Nickel Manganese—7/64" (2.8 mm)diameter wire should be deposited with the open arconly, using DCEP (Electrode Positive). The recom-mended amperage range is 175-275 amperes at 30-35arc volts.Austenitic manganese steel should not be overheatedbecause loss of ductility may result. Use a skip-weldingtechnique to keep the manganese base metal below600°F (300°C).Typical Mechanical Properties:Wear-O-Matic Nickel Manganese wire deposits highstrength, ductile weld metal having excellent resistanceto impact with moderate abrasion resistance. The welddeposit improves with work-hardening, and is notmachinable. It can be cut with an oxy-acetylene flameand by air carbon-arc cutting.Hardness of Deposited Metal:Two layer deposit on austenitic manganese steel:As Welded—90 Rockwell CWork-Hardened—48 Rockwell CAbrasion Resistance: Moderate—improves with coldworkingImpact Resistance: ExcellentMachinability: Non-machinable. Finish by grinding.Relief Checking: NoneDeposit Thickness: Multiple layers may be applied.

Typical Undiluted Weld Metal Analysis (%)C Mn Si Ni

0.60 13.50 0.60 3.90

8.9.2.1 Wear-O-Matic 3No AWS ClassificationDCEP or DCEN (Electrode Positive or Negative)Open Arc—Buildup AlloyHigh Impact ResistanceCarbon Steels; Low Alloy SteelsDescription:Wear-O-Matic 3, a 7/64" (2.8 mm) diameter open-arcwire, is a buildup alloy for multiple layer application onall weldable carbon and low alloy steels. The welddeposit is sound and machinable.Wear-O-Matic 3 is recommended for the rebuilding ofcarbon and low alloy steel parts prior to hardsurfacing orfor use where a machinable resurfacing alloy is re-quired.Procedure:The Wear-O-Matic 3 wire should be deposited with theopen arc only, using direct current, straight or reversepolarity. The recommended amperage range is 225-350amperes at 30-40 arc volts. A weaving technique isrecommended when a machinable deposit or multiplelayer buildup is desired. Stringer beads may be used;however, this produces a harder deposit and should belimited to three passes.Preheat is not required for weld metal. A 200°F (98°C)preheat is recommended to prevent excessive deposithardness when a small deposit is to be applied to aheavy section and the deposit is to be machined. Therequirement for preheat usually depends on the proper-ties of the base metal. The higher alloy steels generallyrequire some preheat.Typical Mechanical Properties:The tough deposits of Wear-O-Matic 3, through theaddition of manganese and molybdenum in balance withother alloying elements, produce a buildup structure forcarbon and low-alloy steels which is highly resistant todeformation and impact. Although this alloy has highcompressive strength and excellent ductility, Wear-O-Matic 3 is not appropriate for use as a high strengthjoining alloy.Hardness of Deposited Metal:Two layer deposit on 1045 steel—weaving technique—30 Rockwell CStringer bead—36 Rockwell CAbrasion Resistance: ModerateImpact Resistance: HighCompressive Strength: HighMachinability: ExcellentRelief Checking: NoneTypical Undiluted Weld Metal Analysis (%)

C Mn Si Cr Mo

0.07 2.00 2.00 0.50 0.50


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LESSON VIII

8.9.2.3 Wear-O-Matic BRNo AWS ClassificationComposite Metal Cored WireDCEP (Electrode Positive)Gas Shielded-Buildup AlloyBolster RepairDescription:The bolster wire is a gas shielded fabricated wiredesigned for the repair and reclamation of railroadfreight car bolster bowls. This wire was designed to beused with the Gas Metal Arc Welding process with a98% argon/2% oxygen shielding gas mixture. With themetal cored process and the argon/oxygen shielding, a98% deposition efficiency is possible. In addition, thewire deposits a spatter-free, slag-free weld having a 35-40 Rockwell C undiluted weld hardness. It offersexcellent abrasion resistance, but does not undulyimpair machinability.Wear-O-Matic BR is recommended for the 40 through100 ton bolsters of either grade “B” or “C” type castings.Another application is the rebuilding of railroad couplers.The excellent combination between hardness andductility provides use where an unlimited layer buildupwire is needed. Depending on the carbon content andmaterial thickness, preheat may be necessary to preventcracking.Procedure:Wear-O-Matic BR is recommended to be used either inthe semiautomatic or full automatic welding mode usinga variable speed weld fixture to rotate the bolster. Whenwelding in the automatic mode, there are only twoadjustments the operator must be concerned with; theyare electrode “stick-out” and the horizontal adjustmentfor overlapping of each weld.The first step in bolster repair is to chamfer the wornarea of the female lip by air carbon-arc cutting, prefer-ably with a 5/8" x 3/16" x 12" (15.9 mm x 4.8 mm x 12.7mm) flat electrode. The female lip of the center of thebolster should be beveled approximately 1/8" (3.2 mm)from the O.D. of the top of the raised area of the female,to approximately a 45° bevel to the bottom seat of thecenter female section of the bolster. This will serve toopen up this area into a 45° square butt to the widestpoint of wear across the top of the raised casting. Thelarge amount of wear resistant weld metal from the topof the buildup joint down to the root will serve to givemuch longer life to this very important part of the totalbolster. It will especially counteract the upsetting or flowof metal common to the impacting of any force to anedge of this kind.

1. Chamfer the total circumference of the femaleflange at a 45° angle-1/8" (3.2 mm) from the O.D. of thefemale flange to the bottom seat of the flange.

2. Clean all excess or loose slag residue left from thecarbon-arc or flame cutting operation. If bolster ismachined as above, cleaning is unnecessary.

3. Place proper size bolster ring of either the 14" x 1-1/8" (356 mm x 28.6 mm) or 14" x 1-3/8" (356 mm x 34.9mm) size, using centering device from 2" (50.8 mm)holding pin hole of the bolster; tack weld ring in placeusing a 3 IP or E7018 electrode to the female bottom ofthe bolster casting.


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LESSON VIII

1. The use of a fabricated wire permits precise controlof the weld metal composition.

2. The use of the inert shielding gas permits a spray-type transfer having minimum penetration andspatter. In addition, slag removal is completelyeliminated.

3. Costs of reclamation are reduced 60% overShielded Metal Arc Welding and covered wiresthrough labor saved with the metal cored process.

4. A bolster bowl repaired with the Wear-O-Matic BRwire has 300-400% more longevity than the originalcasting.

5. The wire produces a weld that is more resistant tometal roll-overs and metal upset caused by severeimpacting at the high speed the railroad industryoperates today.

6. The same wire can be used for building up pads onbolster castings, along with a variety of other wearresistant applications in railroad maintenanceshops.

7. Weld deposits can be cut with oxy-acetylene torchor by air carbon-arc cutting.

Hardness TypicalRange, Hardness

Deposit Condition (Undiluted) Rc(1) Rc

3 layers on C1020, as welded 35 to 40 373 layers on C1020, stress relieved (2) 25 to 30 27Undiluted, as welded 35 to 40 38Undiluted, stress relieved (2) 28 to 30 28

(1) Welded using 98% Argon/2% Oxygen Shielding Gas

(2) Stress relieved for one (1) hour at 1150°F ± 25°F

(621°C ± 14°C)


0.12 1.60 0.37 2.50 0.55

Wear-O-Matic BR (cont’d. from previous page)

4. Use approximately six (6) tack welds equallyspaced. Remove centering device used. The bolster ringnow serves as the inner wall or square portion of thegroove to be built up with the wear material.

5. Preheat casting in the heavy center portion of thebolster to be built up to 150°F (66°C) if a Grade “B”,250° (121°C) if Grade “C”. This will minimize thepossibility of cracking.

6. It is necessary to use only water-cooled equipment,guns, water-circulating equipment, etc. Put in the firstpass at the root of the square butt joint using either the1/16" (1.6 mm) or 5/64" (2.0 mm) Wear-O-Matic BRelectrode with a lagging gun angle to assure proper gas

oxygen gas mix is recommended for use with thiselectrode. Be sure to put in a shallow first pass ifnecessary with the same size wire.

7. All consecutive buildup passes necessary shouldbe made using the 3/32" (2.4 mm) Wear-O-Matic BRelectrode with a lagging gun angle. This will speedcompletion of building up this section of the bolster. Thelast pass can be made to the inside edge of the bolsterring to the outside edge of the female lip of the casting,making a finish pass over this entire surface.

8. A single 3/16" (4.8 mm) fillet weld should be madearound the I.D. of the tack welded preplaced bolsterring, using the 3IP or the Wear-O-Matic BR alloy. Thiswill tend to give added wear in this area.

We recommend 25 to 40 cubic feet of gas per hour anda water-cooled torch. The following amperes and voltsfor the three (3) size wires can be used as a guide:

3/32" (2.4 mm) Wear-O-Matic BR 325/375 AmpereDCEP 29/31 Volts



Typical Properties and Features:


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coverage. A 98% argon/2% oxygen, or 95% argon/5%


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LESSON VIII

8.9.2.4 Wear-O-Matic WHNo AWS ClassificationDCEP (Electrode Positive)Open Arc—Buildup AlloyWear Resistant—Attachment WeldingManganese and Low Alloy SteelsDescription:Wear-O-Matic WH alloy is a dual purpose wire for use ofthe economic, semiautomatic open arc process whenwelding manganese to carbon steel and for buildupapplications involving severe impact or compressiveloads. The high alloy content of this fabricated wire isbalanced to perform a dual function, retaining the highstrength properties of a good attachment weldingmaterial while also serving as an excellent work-hardening, wear-resistant buildup material. The weldmetal is austenitic at room temperature.Procedure:Wear-O-Matic WH is manufactured in 7/64" (2.8 mm)diameter, designed for semiautomatic, open arcapplication.Operation: Open Arc only—DCEP (Electrode Positive)Amperage: 225 to 300 amps, at 30-35 volts

Attachment Welding:Wear-O-Matic WH is suitable for production fabricationof manganese steel and alloy steel parts which formerlyrequired the use of a wire such as 308 stainless. Wear-O-Matic WH gives the user the added advantage ofsemiautomatic welding. The outstanding physicalproperties of Wear-O-Matic WH weld metal are valuablein the field maintenance attachment welding of dipperteeth, tractor grousers, blade replacements, rounds andflats used as wear plates.

Typical Mechanical Properties:Wear-O-Matc WH weld metal is tough and resilient, andprovides strong, crack-resistant welds. The surface ofthe deposit is work-hardenable, especially by impact.However, the mass of material under this work-hardenedsurface remains strong and tough, resisting upset,overroll, and spalling. For this reason, Wear-O-MaticWH is an excellent underlay for hardsurfacing alloys onparts subject to heavy impact and compressive loads.

As Welded

Yield Strength, psi (MPa) 70,100 (483)Tensile Strength, psi (MPa) 102,900 (709)% Elongation in 2" (51 mm) 36Fracture Test SoundFissures None

8.9.2.5 Wear-O-Matic Super WH

No AWS ClassificationDCEP (Electrode Positive)Open Arc-Hardsurfacing AlloySevere Impact Resistance with some AbrasionDescription:Wear-O-Matic Super WH deposits a tough, work-hardenable alloy weld metal.Wear-O-Matc Super WH is intended for the buildup oroverlay of objects subjected to severe impact or impactwith some abrasion. It may be used for multiple layersurfacing without cracking or spalling.Procedure:Wear-O-Matic Super WH - 7/64" (2.8 mm) size shouldbe welded by the open arc process only, using directcurrent, reverse polarity. An electrode extension “stick-out” of about two inches from the contact tip to the workshould be used with 300-450 amperes. Either weavingor stringer bead technique may be used satisfactorily.Typical Mechanical Properties:The tough alloy combination of the weld metal depositedby Wear-O-Matic Super WH gives it outstandingresistance to impact in service. The impacted surface ofthe weld metal work-hardens to the extent that it resistswear from combined impact and abrasive service.Hardness of Deposited Metal:Two layer deposit on 1045 steel:As Welded—30 Rockwell CWork-Hardened—46 Rockwell CSix layer deposit on 1045 steel:As Welded—30 Rockwell CWork-Hardened—47-49 Rockwell C

Typical Undiluted Weld Metal Analysis (%)C Mn Si Cr Ni

1.10 15.00 0.65 17.00 1.40

Hardness of Deposited Metal:Two layer deposit on 1045 steel:As Welded—18 Rockwell CWork-Hardened—41 Rockwell CTypical Undiluted Weld Metal Analysis (%)

C Mn Si Cr Ni

0.38 4.23 0.47 20.20 9.65


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LESSON VIII

8.9.2.6 Wear-O-Matic 6No AWS ClassificationDCEP or DCEN (Electrode Positive or Negative)Open Arc-Hardsurfacing AlloySevere Impact with AbrasionCarbon Steel, Low Alloy Steel, Manganese SteelDescription:Wear-O-Matic 6, a 7/64" (2.8 mm) diameter open-arcwire, is a hardsurfacing alloy wire designed to provideimpact and abrasion resistance. It may be applied tocarbon, low alloy and manganese steel parts.Wear-O-Matic 6 is recommended for applicationsinvolving impact and abrasion on such parts as con-veyor buckets, dragline and power shovel bucket lipsand sides, scraper blades, and dredge bucket parts.Procedure:Wear-O-Matic 6 - 7/64" (2.8 mm) diameter wire shouldbe deposited with the open arc only, using direct current,straight or reverse polarity. The recommended amper-age range is 250-400 amperes at 30-40 arc volts.Weaving beads are recommended to develop maximumwear resistance in this alloy.Preheat is not required for sound weld metal on two-layer deposits. Where deposits over 1/4" (6.4 mm) inthickness are desired, a preheat and interpass tempera-ture of at least 400°F (204°C) is recommended in orderto achieve maximum impact and compressive wearresistance.Typical Mechanical Properties:Wear-O-Matic 6 open-arc wire is a chromium molybde-num alloy combining exceptionally good compressivestrength with high hardness. Deposits may be heattreated and are forgeable. Weld deposits can be cut withoxy-acetylene torch or by air carbon-arc cutting.Hardness of Deposited Metal:Two layer deposit on 1045 steel—weaving technique—48 Rockwell CAbrasion Resistance: ModerateImpact Resistance: Very HighCompressive Strength: HighMachinability: Machinable with carbide toolsRelief Checking: NoneTypical Undiluted Weld Metal Analysis (%)

C Mn Si Cr Mo

0.65 2.60 0.20 3.00 0.50

8.9.2.7 Wear-O-Matic 12No AWS ClassificationDCEP (Electrode Positive)Open Arc-Hardsurfacing AlloyHeavy Impact and Severe Abrasion

Description:Wear-O-Matic 12 - 7/64" (2.8 mm) diameter wire is a hardsurfacing alloy combining good compressivestrength and hardness to provide excellent resistance towear caused by heavy impact and abrasion.Wear-O-Matic 12 is also recommended for power shoveland dragline bucket parts, dredge buckets, andhammermill parts.Procedure:Wear-O-Matic 12 - 7/64" (2.8 mm) diameter wire shouldbe deposited with the open arc only, using direct current,reverse polarity. The recommended amperage range is175-300 amperes at 30-35 arc volts. A weaving tech-nique is recommended to develop maximum abrasionand impact resistance. Application thickness should belimited to two passes or 1/4" (6.4 mm).Typical Mechanical Properties:The deposit of Wear-O-Matic 12 open-arc wire has goodcompressive strength. It is not machinable and cannotbe forged. Relief checks may occur with this alloy but donot impair its performance. Weld deposits cannot be cutwith oxy-acetylene torch or by air carbon-arc cutting.Hardness of Deposited Metal:Two layer deposit on 1045 steel—weaving technique—50 Rockwell CAbrasion Resistance: HighImpact Resistance: ExcellentCompressive Strength: Excellent


2.30 0.30 1.00 17.00 0.80


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LESSON VIII

8.9.2.9 Wear-O-Matic 40No AWS ClassificationDCEP (Electrode Positive)Open Arc-Hardsurfacing AlloySevere Abrasion and CompressionDescription:Wear-O-Matic 40 - 7/64" (2.8 mm) diameter wireis a hardsurfacing alloy with high chromium and carboncontent. It is designed to provide outstanding resistanceto wear caused by abrasion in combination with com-pression. These wear-resistant properties are retainedat temperatures up to 1000°F (538°C). Deposits take ahigh polish and do not gall or seize when subjected tometal-to-metal wear.The unique wear-resistant properties of Wear-O-Matic40 allow a wide variety of applications:Crusher partsHammermill partsSteel mill partsMill guidesProcedure:Wear-O-Matic 40 - 7/64" (2.8 mm) diameter wire shouldbe deposited with the open arc only, using direct current,reverse polarity. The recommended amperage range is175-300 amperes at 30-35 arc volts. A weaving beadof 1-1/2" (38 mm) in width is recommended. Depositthickness should be limited to two passes or 1/4" (6.4 mm).Typical Mechanical Properties:Wear-O-Matic 40 open-arc wire is a high alloy materialcombining chromium and carbon with other alloyingelements to provide extremely high abrasion resistanceand good compressive strength. The deposit is not heattreatable and cannot be forged. Weld deposits cannotbe cut with oxy-acetylene torch or by air carbon-arccutting.Hardness of Deposited Metal:Two layer deposit on 1045 steel—weaving technique—58 Rockwell CAbrasion Resistance: ExcellentHeat Resistance: Excellent up to 1000°F (538°C)Impact Resistance: LightCompressive Strength: GoodMachinability: Non-machinable. Finish by grinding.Relief Checking: A uniform pattern of check cracksappears in the deposit as it cools, indicating the excel-lent stress-relief characteristics of this alloy. This checkcrack pattern is necessary to prevent distortion in largeparts when an alloy of this hardness and alloy content isapplied.


4.00 1.50 1.50 27.00 1.00

8.9.2.8 Wear-O-Matic 15No AWS ClassificationDCEP or DCEN (Electrode Positive or Negative)Open Arc-Hardsurfacing AlloySevere Abrasion ResistanceDescription:Wear-O-Matic 15 - 7/64" (2.8 mm) diameter open arcwire is a hardsurfacing alloy with outstanding resistanceto wear caused by severe abrasion.Wear-O-Matic 15 produces extremely high abrasion-resistant qualities that make it an outstanding surfacematerial for pug mill knives and augers, dry cementpump screws, conveyor screws, and asphalt mixerpaddles and shanks.Procedure:Wear-O-Matic 15 - 7/64" (2.8 mm) diameter wire shouldbe deposited with the open arc only, using direct current,straight or reverse polarity. Recommended amperagerange, 175-300 amperes at 30-35 arc volts. Weavingbead of 1-1/2" (38 mm) in width is recommended inorder to develop maximum abrasion-resistant qualitiesin the deposit. Deposit thickness should be limited totwo passes or 1/4" (6.4 mm).Typical Mechanical Properties:The deposit of Wear-O-Matic 15 open-arc wire attainsmaximum hardness as deposited and is unaffected byheat treatment. In most cases, stress relief check cracksappear in the deposit but do not impair the abrasionresistance or the ability of the deposit to take a highpolish. Weld deposits cannot be cut with oxy-acetylenetorch or by air carbon-arc cutting.Hardness of Deposited Metal:Two layer deposit on 1045 steel—weaving technique—60 Rockwell CAbrasion Resistance: OutstandingImpact Resistance: LightCompressive Strength: HighMachinability: Non-machinable. Finish by grinding.


4.00 0.30 0.60 5.50 5.00


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LESSON VIII

APPENDIX ALESSON VIII - GLOSSARY OF TERMS

Spalling - The loss of particles or pieces from a surface due to cracking.

Galling - The condition between rubbing surfaces where high spots or protrusions

on a surface become friction welded to the mating surface, resulting in

spalling and further deterioration.

Matrix - A crystalline phase of an alloy in which other phases are imbedded.

Shear - A force which causes deformation or fracture of a member by sliding one

section against another in a plane or planes which are substantially

parallel to the direction of the force.

HadfieldSteel

- The name sometimes used for austenitic manganese steel derived from

its inventor.

Coefficientof Friction

- A value used in engineering calculations which is an indicator of the

ability of one material to slide on another. A low coefficient of friction

indicates a low rate of wear between sliding surfaces.

StringerBead

- A straight weld bead opposed to a weaving bead. In surfacing, the

weaving bead produces less dilution because the weld puddle is always

in contact with the part of the bead produced on the previous oscillation

rather than the base metal.


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TECHNOLOGY


LESSON IX

ESTIMATINGAND COMPARING

WELD METAL COSTS




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TABLE OF CONTENTSLESSON IX

ESTIMATING AND COMPARING WELDMETAL COSTS


9.1 Introduction .................................................................................................. 1

9.2 Factors For Cost Formulas ...................................................................... 2

9.2.1 Labor & Overhead ......................................................................................... 2

9.2.2 Deposition Rate ............................................................................................. 2

9.2.3 Operating Factor ............................................................................................ 3

9.2.4 Deposition Efficiency .................................................................................... 4

9.2.5 Deposition Efficiency of Coated Electrodes .............................................. 4

9.2.6 Efficiency of Flux Cored Wires ..................................................................... 6

9.2.7 Efficiency of Solid Wires for GMAW ............................................................ 6

9.2.8 Efficiency of Solid Wires for SAW ............................................................... 7

9.2.9 Cost of Electrodes, Wires, Gases and Flux ................................................ 7

9.2.10 Cost of Power ................................................................................................ 7

9.3 Deposition Data Tables ............................................................................. 8

9.4 Cost Calculations ....................................................................................... 12

9.4.1 Calculating the Cost Per Pound of Deposited Weld Metal ....................... 12

9.4.2 Calculating the Cost Per Foot Of Deposited Weld Metal ......................... 14

9.5 Cost Calculations - Example 2 ................................................................ 15

9.6 Comparing Weld Metal Costs .................................................................. 17

9.6.1 Example 3 ....................................................................................................... 19

9.7 Other Useful Formulas .............................................................................. 20

9.8 Amortization of Equipment Costs .......................................................... 21

Appendix A Lesson IX Test Questions ......................................................................... 22

Appendix B Problem 1 Worksheet ................................................................................ 26

Appendix C Problem 2 Worksheet ................................................................................ 27


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LESSON IX

ESTIMATING AND COMPARING WELD METAL COSTS

9.1 INTRODUCTION

Estimating the costs of depositing weld metal can be a difficult task because of the many

variables involved. Design engineers must specify the type and size of weld joint to withstand

the loads that the weldment must bear. The welding engineer must select the welding process,

and type of filler metal that will provide the required welds at the least possible cost. With

wages and the cost of operations rising, selection of the process that deposits weld metal

most expediently must be carefully considered. Labor and overhead account for approxi-

mately 85% of the total welding cost.

9.1.0.1 Welding costs may be divided into two categories; the “fixed” costs involved regard-

less of the filler metal or welding process selected, and those related to a specific welding

process. Fixed costs entail material handling, joint preparation, fixturing, tacking, preheating,

weld clean-up and inspection. Although some of these items will be affected by the process

and filler metal chosen, they are a necessary part of practically all welding operations. Calcu-

lating these costs is best left to the manufacturer since they will depend upon his capabilities

and equipment. The cost of actually depositing the weld metal however, will vary considerably

with the filler metal and welding process selected. This cost element is influenced by the

user’s labor and overhead rates, deposition rate and efficiency of the filler metal, operating

factor, and cost of materials and power.

9.1.0.2 This lesson will cover cost estimating for steel weldments produced by the four most

common arc welding processes in use today: shielded metal-arc welding, gas metal-arc

welding, flux cored arc welding and submerged arc welding. Gas tungsten arc welding will not

be considered here because the variables, such as deposition rate and efficiency, are depen-

dent on operator technique, stub use, etc. The GTAW process is a relatively costly method of

depositing weld metal, and is usually chosen for weld quality or material thickness and compo-

sition limitations, rather than economy.

9.1.0.3 Large firms will frequently conduct their own deposition tests and time studies to

determine welding costs, but many smaller shops do not know the actual cost of depositing

weld metal.

9.1.0.4 In estimating welding costs, all attempts should be made to work with accurate data,

which in some cases is difficult to secure. For this reason, this lesson contains charts, graphs


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LESSON IX

and tables that provide average values that you may use. Electrode manufacturers will usually

supply the deposition data you need through their Technical Services Department, if it is not

already published in their literature.

9.2 FACTORS FOR COST FORMULAS

9.2.1 Labor and Overhead - Labor and overhead may be considered jointly in your

calculations. Labor is the welder’s hourly rate of pay including wages and benefits. Overhead

includes allocated portions of plant operating and maintenance costs. Weld shops in manu-

facturing plants normally have established labor and overhead rates for each department.

Labor and overhead rates can vary greatly from plant to plant, and also with location. Figure 1

shows how labor and overhead may vary and suggests an average value to use in your calcu-

lations when the actual value is unknown.

9.2.2 Deposition Rate - The deposition rate is the rate that weld metal can be deposited

by a given electrode or welding wire, expressed in pounds per hour. It is based on continuous

operation, not allowing time for stops and starts caused by inserting a new electrode, cleaning

slag, termination of the weld or other reasons. The deposition rate will increase as the welding

current is increased.

9.2.2.1 When using solid or flux cored wires, deposition rate will increase as the electrical

stick-out is increased, and the same amperage is maintained. True deposition rates for each

welding filler metal, whether it is a coated electrode or a solid or flux cored wire, can only be

established by an actual test in which the weldment is weighed before welding and then again

after welding, at the end of a measured period of time. The tables in Figures 8-11 contain

average values for the deposition rate of various types of welding filler metals. These are

based on welding laboratory tests and published data.

FIGURE 1

HOURLY WELDING LABOR & OVERHEAD RATES

Small Shops $10.00 to $25.00/hr.Large Shops $25.00 to $50.00/hr

Average $30.00/hr.

APPROXIMATE LABOR AND OVERHEAD RATES


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LESSON IX

9.2.3 Operating Factor - Operating factor is the percentage of a welder’s working day

that is actually spent welding. It is the arc time in hours divided by the total hours worked. A

45% (.45) operating factor means that only 45% of the welder’s day is actually spent welding.

The balance of time is spent installing a new electrode or wire, cleaning slag, positioning the

weldment, cleaning spatter from the welding gun, etc.

9.2.3.1 When using coated electrodes, (SMAW) the operating factor can range from

15%-40% depending upon material handling, fixturing and operator dexterity. If the actual

operating factor is not known, an average of 30% may be used for cost estimates when weld-

ing with the shielded metal arc welding process.

9.2.3.2 When welding with solid wires (GMAW) or metal cored welding (MCAW) using the

semi-automatic method, operating factors ranging from 45%-55% are easily attainable. Use

50% for cost estimating purposes.

9.2.3.3 For welds produced by flux cored arc welding (FCAW) semi-automatically, the

operating factor usually lies between 40%-50%. For cost estimating purposes, use a 45%

operating factor. The estimated operating factor for FCAW is about 5% lower than that of

GMAW to allow for slag removal time.

9.2.3.4 In semi-automatic submerged arc welding, slag removal and loose flux handling

must be considered. A 40% operating factor is typical for this process.

9.2.3.5 Automatic welding using the GMAW, FCAW, and SAW processes, requires that

each application be studied individually. Operating factors ranging from 50% to values ap-

proaching 100% may be obtained depending on the degree of automation.

9.2.3.6 The chart in Figure 2 shows average operating factor values for the various welding

processes that may be used for cost estimating when the actual operating factor is not known.

FIGURE 2

WELDING PROCESS

SMAW * GMAW *FCAW *SAW

30% 50% 45% 40%

*Semi-Automatic Only+ Metal Cored Wires are Included

APPROXIMATE OPERATING FACTOR

+


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-4-© COPYRIGHT 2000 THE ESAB GROUP, INC.

LESSON IX

9.2.4 Deposition Efficiency - Deposition efficiency is the relationship of the weight of

the weld metal deposited to the weight of the electrode (or wire) consumed in making a weld.

It can be accurately determined only by making a timed test weld, and carefully weighing the

weldment and the electrode or wire, before and after welding. The efficiency can then be

calculated by the formula:

Deposition efficiency = Weight of Weld Metal ÷ Weight of Electrode Used(or)

Deposition Rate (lbs/hr) ÷ Burn-off Rate (lbs/hr)

9.2.4.1 The deposition efficiency tells us how many pounds of weld metal can be expected

from a given weight of the electrode or welding wire purchased. As an example, 100 pounds

of a flux cored electrode with an efficiency of 85%, will produce approximately 85 pounds of

weld metal, while 100 pounds of coated electrode with an efficiency of 65%, will produce

approximately 65 pounds of weld metal, less the weight of the stubs discarded, as described

below.

9.2.5 Coated Electrodes - The deposition efficiency of coated electrodes by AWS

definition, and in published data, does not consider the loss of the unused electrode stub that

is discarded. This is understandable since the stub length can vary with the operator and the

application. Long continuous welds are usually conducive to short stubs while on short inter-

mittent welds, stub length tends to be longer. Figure 3 illustrates how the stub loss influences

the electrode efficiency when using coated electrodes.

9.2.5.1 In Figure 3, a 14” long by 5/32” diameter E7018 electrode at 140 amperes is con-

sidered. It is 75% efficient, and a two inch stub loss is assumed. The 75% efficiency applies

FIGURE 3

DEPOSITION EFFICIENCY = 75%actual efficiency, including stub loss = 9 ÷ 14 = 64.3%

12" LENGTH OF ELECTRODE CONSUMED

AMOUNT THAT BECOMES WELD METAL(LENGTH CONSUMED X EFFICIENCY)

14"

LOST TOSLAG,SPATTER

& FUMES

2"STUB

LENGTH

9"


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LESSON IX

only to the 12” of the electrode consumed in making the weld, and not to the two inch stub.

When the two inch stub loss and the 25% that is lost to slag, spatter and fumes are consid-

ered, the efficiency minus stub loss is lowered to 64.3%. This means that for each 100 pounds

of electrodes purchased, you can expect an actual deposit of approximately 64.3 pounds of

weld metal if all electrodes are used to a two inch stub length.

9.2.5.2 The formula for the efficiency including stub loss is important, and must always be

used when estimating the cost of depositing weld metal by the SMAW method. Figure 4

shows the formula used to establish the efficiency of coated electrodes including stub loss. It

is based on the electrode length, and is slightly inaccurate, i.e. it does not take into consider-

ation that the electrode weight is not evenly distributed, due to the flux being removed from the

electrode holder end. (Indicated by the dotted lines in Figure 3.) Use of the formula will result

in a 1.5-2.3% error that will vary with electrode size, coating thickness and stub length. The

formula however, is acceptable for estimating purposes.

9.2.5.3 For the values given in Figure 3 the formula is:

Efficiency - Stub Loss = (14-2) x .75

14

= 12 x .75

14

= 9

14

= .6429 or 64.3%

In the above example, the electrode length is known, the stub loss must be estimated, and the

efficiency taken from the tables in Figures 8 and 9. Use an average stub loss of three inches

for coated electrodes if the actual shop practices concerning stub loss are not known.

9.2.5.4 The following stub loss correction table will assist in your determination of coated

electrode efficiencies. Figure 5 lists various efficiencies at a given stub loss.

EFFICIENCY (ELECTRODE LENGTH — STUB LENGTH) X DEPOSITION EFFICIENCYELECTRODE LENGTH

=

EFFICIENCY MINUS STUB LOSS

FIGURE 4

MINUS STUB LOSS


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LESSON IX

9.2.6 Efficiency of Flux Cored Wires - Flux cored wires have a lower flux-to-metal ratio

than coated electrodes, and thereby, a higher deposition efficiency. Stub loss need not be

considered since the wire is continuous. The gas shielded wires of the E70T-1 and E70T-2

types have efficiencies of 83%-88%. The gas shielded basic slag type (E70T-5) is 85%-90%

efficient with CO2 as the shielding gas, and the efficiency can reach 92% when a 75% argon,

25% CO2 gas mixture is used. Use the efficiency figures in Figure 9 for your calculations if the

actual values are not known.

9.2.6.1 The efficiency of the self-shielded types of flux cored wires has more variation

because of the large variety of available types that have been designed for specific applica-

tions. The high deposition general purpose type, such as E70T-4, is 81%-86%, depending on

wire size and electrical stick-out. The chart in Figure 9 shows the optimum conditions for each

wire size and may be used in your calculations.

9.2.7 Efficiency of Solid Wires for GMAW - The efficiency of solid wires in GMAW is

very high and will vary with the shielding gas or gas mixture used. Using CO2 will produce the

most spatter and the average efficiency will be about 93%. Using a 75% argon-25% CO2 gas

mixture will result in somewhat less spatter, and an efficiency of approximately 96% can be

expected. A 98% argon-2% oxygen mixture will produce even less spatter, and the average

efficiency will be about 98%. Stub loss need not be considered since the wire is continuous.

Figure 6 shows the average efficiencies you may use in your calculations if the actual effi-

ciency is not known.

FIGURE 5

ELEC. DEPOSITION 2" 3" 4" 5"LENGTH EFFICIENCY STUB STUB STUB STUB

60% 50.0% 45.0% 40.0% 35.0%

65% 54.2% 48.7% 43.3% 37.9%

12" 70% 58.3% 52.5% 46.6% 40.8%

75% 62.5% 56.2% 50.0% 43.7%

80% 66.6% 60.0% 53.3% 46.6%

60% 51.4% 47.1% 42.8% 38.5%

65% 55.7% 51.1% 46.4% 41.8%

14" 70% 60.0% 55.0% 50.0% 45.0%

75% 64.3% 58.9% 53.6% 48.2%

80% 68.5% 62.8% 57.1% 51.4%

60% 53.3% 50.0% 46.6% 43.3%

65% 57.7% 54.2% 50.5% 46.9%

18" 70% 62.2% 58.3% 54.4% 50.5%

75% 66.6% 62.5% 58.3% 54.2%

80% 71.1% 66.6% 62.2% 57.7%

STUB LOSS CORRECTION

TABLE FOR COATED

ELECTRODES

EFFICIENCY INCLUDING

STUB LOSS


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.045" - 1/16"

GMAW


LESSON IX

9.2.8 Efficiency of Solid Wires for SAW - In submerged arc welding there is no spatter

loss and an efficiency of 99% may be assumed. The only loss during welding is the short

piece the operator must clip off the end of the wire to remove the fused flux that forms at the

termination of each weld. This is done to assure a good start on the succeeding weld.

9.2.9 Cost of Electrodes, Wires, Gases and Flux - You must secure the current cost

per pound of the electrode or welding wire, plus the cost of the shielding gas or flux if appli-

cable, from the supplier. The shielding gas flow rate varies slightly with the type of gas used.

The flow rates in Figure 7 are average values whether the shielding gas is an argon mixture or

pure CO2. Use these in your calculations if the actual flow rate is not available.

In the submerged arc process (SAW) the ratio of flux to wire consumed in the weld is approxi-

mately 1 to 1 by weight. When the losses due to flux handling and flux recovery systems are

considered, the average ratio of flux to wire is approximately 1.4 pounds of flux for each pound

of wire consumed. If the actual flux-to-wire ratio is unknown, use the 1.4 for cost estimating.

9.2.10 Cost of Power - Cost of electrical power is a very small part of the cost of deposit-

ing weld metal and in most cases is less than 1% of the total. It will be necessary for you to

know the power cost expressed in dollars per kilowatt- hour ($/kWh) if required for a total cost

estimate.

FIGURE 6

ShieldingGas

EfficiencyRange

AverageEfficiency

Pure CO2 88 - 95% 93%

94 - 98% 96%

98% Ar - 2% O2 97 - 98.5% 98%

DEPOSITION EFFICIENCIES - GAS METAL ARC WELDINGCARBON AND LOW ALLOY STEELS

Wire Diameter .035" .045" 1/16" 5/64" - 1/8"

CFH 30 35 35 40 45

FCAW/MCAW

APPROXIMATE SHIELDING GAS FLOW RATE - CUBIC FEET PER HOUR

FIGURE 7


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LESSON IX

9.3 DEPOSITION DATA CHARTS

9.3.1 SHIELDED METAL ARC WELDING - Coated Electrodes.

DEPOSITION DATA - SMAW - COATED ELECTRODES

FIGURE 8

NOTE: EFFICIENCY RATES DO NOT INCLUDE STUB LOSS

E6011ELECTRODE DEPOSITION EFFICIENCY

DIAMETER AMPS RATE lbs/hr %

3/32 75 1.3 61.0%1/8 120 2.3 70.7%5/32 150 3.7 77.0%3/16 180 4.1 73.4%7/32 210 5 74.2%1/4 250 5.6 71.9%



1/8 130 2.9 81.8%5/32 165 3.2 78.8%

200 3.4 69.0%3/16 220 4 77.0%

250 4.2 74.5%7/32 320 5.6 69.8%

6013ELECTRODE DEPOSITION EFFICIENCY


3/32 85 1.6 73.0%1/8 125 2.1 73.0%5/32 140 2.6 75.6%

160 3 74.1%180 3.5 71.2%

3/16 180 3.2 73.9%200 3.8 71.1%220 4.1 72.9%

7/32 250 5.3 71.3%270 5.7 73.0%290 6.1 72.7%



1/8 120 2.4 63.9%150 3.1 61.1%

5/32 160 3 71.9%200 3.7 67.0%

3/16 230 4.5 70.9%270 5.5 73.2%

7/32 290 5.8 67.2%330 7.1 70.3%

1/4 350 7.1 68.7%400 8.7 69.9%

E6010ELECTRODE DEPOSITION EFFICIENCYDIAMETER AMPS RATE lbs/hr %

3/32 75 1.5 72.0%1/8 100 2.1 76.3%

130 2.3 68.8%5/32 140 2.8 73.6%

170 2.9 64.1%3/16 160 3.3 74.9%

190 3.5 69.7%7/32 190 4.5 76.9%

230 5.1 73.1%


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LESSON IX

DEPOSITION DATA - SMAW - COATED ELECTRODES (Con't.)

FIGURE 9

NOTE: EFFICIENCY RATES DO NOT INCLUDE STUB LOSS



1/8 100 1.7 63.9%130 2.3 65.8%

5/32 140 3.0 70.5%160 3.2 69.1%190 3.6 66.0%

3/16 175 3.8 71.0%200 4.2 71.0%225 4.4 70.0%250 4.8 65.8%

1/4 250 5.9 74.5%275 6.4 74.1%300 6.8 73.2%350 7.6 71.5%



1/8 140 4.2 71.8%180 5.1 70.7%

5/32 180 5.3 71.3%210 6.3 72.5%240 7.2 69.4%

3/16 245 7.5 69.2%270 8.3 70.5%290 9.1 68.0%

7/32 320 9.4 72.4%360 11.6 69.1%

1/4 400 12.6 71.7%

LOW ALLOY, IRON POWDER ELECTRODESTYPES E7018, E8018, E9018, E10018, E11018,

AND E12018ELECTRODE DEPOSITION EFFICIENCY


3/32 70 1.37 70.5%90 1.65 66.3%110 1.73 64.4%

1/8 120 2.58 71.6%140 2.74 70.9%160 2.99 68.1%

5/32 140 3.11 75.0%170 3.78 73.5%200 4.31 73.0%

3/16 200 4.85 76.4%250 5.36 74.6%300 5.61 70.3%

7/32 250 6.50 75.0%300 7.20 74.0%350 7.40 73.0%

1/4 300 7.72 78.0%350 8.67 77.0%400 9.04 74.0%


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0.045


LESSON IX

FLUX CORED ARC WELDING (FCAW)GAS SHIELDED TYPES E70T-1, E71T-1, E70T-2,

E70T-5, & ALL LOW ALLOY TYPESELECTRODE DEPOSITION EFFICIENCYDIAMETER AMPS RATE lbs/hr %

.035 130 3.2 82%140 3.6 82%160 4.2 83%180 5.6 83%200 6.5 84%220 7.5 85%

.045 160 4.0 83%180 4.9 87%200 6.5 90%220 6.8 84%240 7.3 84%280 10.5 89%

.052 170 3.9 84%190 5.3 87%210 5.5 86%240 6.7 85%270 8.1 85%300 10.3 87%

1/16 180 4.2 87%200 4.7 85%220 5.6 87%250 7.7 86%275 8.5 86%300 9.3 86%350 11.7 86%

5/64 250 6.4 85%350 10.5 85%450 14.8 85%

3/32 400 12.7 85%450 15.0 86%500 18.5 86%

DEPOSITION DATA - FCAW/MCAW

FIGURE 10

METAL CORED ARC WELDING (MCAW)

E70T-1, E71T-1, AND ALL ALLOY TYPESELECTRODE DEPOSITION EFFICIENCY


0.035 150 4.4 93%200 6.5 92%250 9.4 92%250 8 91%275 11.4 93%300 11.6 95%

0.052 275 8 90%300 9.6 93%325 10.1 93%

1/16 300 8.6 89%350 11.9 94%400 14.6 93%450 16.2 96%

5/64 350 11.6 94%400 13.2 95%450 15.8 97%500 20.4 97%

3/32 400 11.5 95%450 14.5 97%500 16.5 97%550 21 98%

NOTE: DATA REFLECTS USE OF 75% ARGON25% CO2 GAS SHIELDING. DEPOSITION RATESAND EFFICIENCIES WILL INCREASE WITH THE USEOF HIGHER ARGON MIXTURES.

9.3.2 FLUX CORED ARC WELDING/METAL CORED ARC WELDING - Deposition

data for gas shielded FCAW on all low alloy wire types and MCAW on all alloy types.


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LESSON IX

SUBMERGED ARC WIRES

(1" STICKOUT)

ELECTRODE MELT-OFF EFFICIENCY


5/64 300 7.0400 10.2500 15.0

3/32 400 9.4500 13.0600 17.2

1/8 400 8.5500 11.5600 15.0700 19.0

5/32 500 11.3600 14.6700 18.4800 22.0900 26.1

3/16 600 13.9700 17.5800 21.0900 25.0

1000 29.21100 34.0

NOTE: Values for 1" Stickout

DEPOSITION DATA

FIGURE 11

FLUX CORED ARC WELDING (FCAW)SELF-SHIELDED

ELECTRODE DEPOSITION EFFICIENCYDIAMETER AMPS RATE lbs/hr %

E70T-3 3/32 450 14 88%E70T-4 3/32 400 15 85%

0.12 450 20 81%E70T-6 5/64 350 11.9 86%

3/32 480 14.7 81%E70T-6 3/32 325 11.4 80%

7/64 450 18 86%E71T-7 .068 200 4.2 76%

5/64 300 8 84%E71T-8 5/64 220 4.4 77%

3/32 300 6.7 77%E61T8-K6 5/64 235 4.3 76%E70T-10 .045 150 2.6 88%

1/16 220 3.3 78%5/64 250 4 94%

E71T-11 .045 150 2.4 82%1/16 200 3.6 83%5/64 240 4.5 87%3/32 250 5 91%

E70T4-K2 3/32 300 14 83%E71T-GS .030 100 1.6 75%

.035 120 2.1 84%

.045 150 2.4 82%1/16 200 3.6 83%5/64 250 3.9 81%

GAS METAL ARC WELDINGSOLID WIRES

DEPOSITION RATE lbs/hrELECTRODE 98%A/2%O275%A/25%CO2Straight CO2DIAMETER AMPS *98% *96% *93%

.030 75 2.0 1.9 1.8100 2.6 2.6 2.5150 4.1 4.0 3.9200 6.8 6.7 6.5

.035 80 2.2 2.1 2.0100 2.7 2.7 2.6150 4.2 4.1 4.0200 6.2 6.0 5.9250 9.0 8.8 8.6

.045 100 2.1 2.0 1.9125 2.8 2.8 2.7150 3.6 3.5 3.4200 5.6 5.5 5.3250 7.8 7.6 7.4300 10.2 10.0 9.7350 13.2 12.9 12.5

1/16 250 6.5 6.4 6.2275 7.7 7.6 7.3300 9.0 8.8 8.5350 11.3 11.0 10.7400 14.0 13.7 13.3450 17.4 17.1 16.5

* USE THIS FIGURE AS THE DEPOSITION EFFICIENCY IN THE COST CALCULATIONS ON SHEET ONE.

9.3.3 FLUX CORED ARC WELDING,

GAS METAL ARC WELDING, AND SUB-

for self-shielded FCAW, and solid wires using

GMAW and SubArc.


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MERGED ARC WELDING - Deposition data

Assume 99% Efficiency


LESSON IX

9.4 COST CALCULATIONS - EXAMPLE 1

9.4.1 Calculating the Cost Per Pound of Deposited Weld Metal

9.4.1.1 Example 1 - Calculate the cost of welding 1,280 ft. of a single bevel butt joint as

shown in Figure 14 using the following data.

a. Electrode - 3/16” diameter, 14” long, E7018, operated at 25 volts, 250 amps.

b. Stub Loss - 2 inches

c. Labor and Overhead - $30.00/hr

d. Electrode Cost - $.57/lb

e. Power Cost - $.045/kWh

9.4.1.2 The formulas for the calculations are shown on the Weld Metal Cost Worksheet in

Figure 12. The following explains each step in the calculations.

Line 1- Labor and Overhead - $30.00/hr (given)

Deposition Rate - From shielded metal arc welding deposition data chart in

Figure 9 = 5.36 lbs/hr.

Operating Factor - Since it is not stated above, use an average value of 30% (.30)

shown in Figure 2.

The cost of labor and overhead per pound of deposited weld metal can now be

calculated as $18.66/lb.

Line 2 - Electrode Cost Per Pound - $.57 (given)

Deposition Efficiency - From the shielded metal arc welding deposition table in

Figure 9 = 74.6%. Since this is a coated electrode, the efficiency must be adjusted

for stub loss by the formula following Figure 3. We know that the electrode length is

14" and the stub loss is 2" (given). The formula becomes:

Efficiency - Stub Loss = (14-2) x .746 ÷ 14 = .639 or 63.9%63.9% is the adjusted efficiency to be used in Line 2.

The cost of the electrode per pound of deposited weld metal can now be calculated

as $.89/lb.

Line 3 - Not applicable for coated electrodes.

Line 4 - Not applicable for coated electrodes.


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LESSON IX

FIGURE 12

EXAMPLE 1WELD METAL COST WORKSHEET

COST PER POUND OF DEPOSITED WELD METAL

LABOR &OVERHEAD

LABOR & OVERHEAD COST/HRDEPOSITION OPERATINGRATE (LBS/HR) x FACTOR

=

ELECTRODE

GAS

FLUX

POWER

ELECTRODE COST/LB

GAS FLOW RATE(CU FT/HR) x GAS COST/CU FT

DEPOSITION RATE (LBS/HR)

FLUX COST/LB x 1.4DEPOSITION EFFICIENCY

COST/kWh x VOLTS x AMPS1000 x DEPOSITION RATE

TOTAL COST PER LB. OFDEPOSITED WELD METAL SUM OF 1 THROUGH 5 ABOVE

DEPOSITION EFFICIENCY=

=

=

=

1.

2.

3.

4.

5.

6.

7.

8.

30.005.36 x .30

30.00

1.60818.66= =

.57

.639= .89

= = N A

X 1.4 = = N A

= =.045 x 25 x 250

1000 x 5.36281.255,360

.052

COST PER FOOT OF DEPOSITED WELD METAL

COST PER POUNDOF DEPOSITEDWELD METAL

XPOUNDS PER

FOOT OFWELD JOINT

$ 19.60

= 19.60x .814 = $15.95

TOTAL FEETOF WELD

=COST PERFOOTX

1,280x 15.95 = $20,422

COST OF WELD METAL - TOTAL JOB


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LESSON IX

Line 5 - Cost of Power - $ .045/kWh (given).

Volts & Amperes - 25V and 250A (given).

Constant - The 1,000 already entered, is a constant necessary to convert to

watt-hours.

Deposition Rate - 5.36 lbs/hr as used in Line 1.

The cost of electrical power to deposit one pound of weld metal can now be

calculated as $.052.

Line 6 - Total Lines 1, 2, and 5 to find the total cost of depositing one pound weld

metal. The total of $19.60.

9.4.2 Calculating The Cost Per Foot of Deposited Weld Metal

Calculating the weight of weld metal requires that we consider the following items.

a. Area of the cross-section of the weld.

b. Length of the weld.

c. Volume of the weld in cubic inches.

d. Weight of the weld metal per cubic inch.

9.4.2.1 In the fillet weld show in Figure 13, we know that the area of the cross-section (the

triangle) is equal to one-half the base times the height, the volume of the weld is equal to the

area times the length, and the weight of the weld then, is the volume times the weight of the

material (steel) per cubic inch.

9.4.2.2 We can then write the formula:

Weight of Weld Metal = ½ x Base x Height x Length x Weight of Material

Substituting the values from Figure 13, we have:

Wt/Ft = .5 x .5 x .5 x 12 x .283 = .4245 lbs

9.4.2.3 Weights may vary depending on the density of the particular material you are at-

tempting to calculate. The chart in Figure 14 will eliminate the need for these calculations for

steel fillet and butt joints, since it lists the weight per foot directly.

9.4.2.4 Estimating the weight per foot of a weld using the chart, requires that you make a

drawing of the weld joint to exact scale, and dimension the leg lengths, root gap, thickness,

angles and other pertinent measurements as shown in Figure 15. Divide the cross-section of

the weld into right triangles and rectangles as shown. Sketch in the reinforcement, i.e., the


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LESSON IX

domed portion above or below the surface of the plate, where required. The reinforcement

should extend slightly beyond the edges of the joint. Measure the length and height of the

reinforcement and note them on your drawing. The reinforcement is only an approximation

because the contour cannot be exactly controlled in welding. Refer to the weight tables in

Figure 14 for the weights per foot of each of the component parts of the weld, as sketched.

The sum of the weights of all the components is the total weight of the weld, per foot as shown

in Figure 15A.

Line 7 - The total cost per pound as determined in Line 6 is entered, and multi-

plied by the weight per foot as determined in Figure 14.

9.4.3 Calculating the Cost of Weld Metal - Total Job

Line 8 - The cost of the weld for the total job is determined by multiplying the total

feet of weld (given) by the cost per foot as determined in Line 7.

9.5 COST CALCULATIONS - EXAMPLE 2

Calculate the total cost of depositing 1,280 ft of weld metal using the CO2 shielded, flux cored

welding process in the double V-groove joint shown in Figure 14 using the following data.

1. Electrode - 3/32”, E70T-1 @ 31 volts, 450 amps.

2. Labor and Overhead - $30.00/hr.

3. Deposition Rate - 15 lbs/hr. From Table in Figure 10.

4. Operating Factor - 45% (.45). Average from Figure 2.

1/2"

1/2"

(A)HEIGHT

(B) BASE

Weight of Steel = .283 lb per cu. in.Weight of Weld = 1/2 (1/2) x 1/2 x 12 x .283

= .424 lbs.

CALCULATING THE WEIGHT PER FOOT OF A FILLET WELD

FIGURE 13


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Volume of Weld = 1/2 B x A x 12


Filler Metals

V-GROOVE


LESSON IX

FIGURE 14

WEIGHT PER FOOT OF WELD METAL FOR FILLET WELDS ANDELEMENTS OF COMMON BUTT JOINTS (lbs/ft)

STEEL

B TT T T T

TT T

T TT

H

G GS SS

S SSSS

C C

C C

B B BAA

CB B

A

B BC

CB

A

B

C

C

B B

lbs./ft. of Rectangle A lbs./ft. of Triangle B lbs./ft. Reinforcement CT G S H

Inches 1/16" 1/8" 3/16" 1/4" 3/8" 1/2" 5° 10° 15° 22 1/2° 30° 45° 1/16" 1/8" 3/16" 1/4"

1/8 .027 .053 .080 .106 .159 .212 .002 .005 .007 .011 .015 .0273/16 .040 .080 .119 .159 .239 .318 .005 .011 .016 .025 .035 .060 .0271/4 .053 .106 .159 .212 .318 .425 .009 .019 .028 .044 .061 .106 .035

5/16 .066 .133 .199 .265 .390 .531 .015 .029 .044 .069 .096 .166 .044 .8843/8 .080 .159 .239 .318 .478 .637 .021 .042 .064 .099 .138 .239 .053 .1067/16 .091 .186 .279 .371 .557 .743 .028 .057 .087 .129 .188 .325 .062 .124

.106 .212 .318 .425 .637 .849 .037 .075 .114 .176 .245 .425 .071 .141 .2129/16 .119 .239 .358 .478 .716 .955 .047 .095 .144 .223 .311 .451 .080 .159 .2395/8 .133 .265 .398 .531 .796 1.061 .058 .117 .178 .275 .383 .664 .088 .177 .265 .35411/16 .146 .292 .438 .584 .876 1.167 .070 .142 .215 .332 .464 .804 .097 .195 .292 .3893/4 .159 .318 .478 .637 .995 1.274 .084 .169 .256 .396 .552 .956 .106 .212 .318 .424

13/16 .172 .345 .517 .690 1.035 1.380 .098 .198 .301 .464 .648 1.121 .115 .230 .345 .4607/8 .186 .371 .557 .743 1.114 1.486 .114 .230 .349 .538 .751 1.300 .124 .248 .371 .49515/16 .199 .398 .597 .796 1.194 1.592 .131 .263 .400 .618 .863 1.493 .133 .266 .398 .5301 .212 .425 .637 .849 1.274 1.698 .149 .300 .456 .703 .981 1.698 .141 .283 .424 .566

.239 .478 .716 .955 1.433 1.910 .188 .379 .577 .890 1.241 2.149 .159 .318 .477 .6371 1/4 .265 .531 .796 1.061 1.592 2.123 .232 .468 .712 1.099 1.532 2.653 .177 .354 .531 .7071 3/8 .292 .584 .876 1.167 1.751 2.335 .281 .567 .861 1.330 1.853 3.210 .195 .389 .584 .7771 1/2 .318 .637 .955 1.274 1.910 2.547 .334 .674 1.023 1.582 2.206 3.821 .212 .424 .637 .849

1 5/8 .345 .690 1.035 1.380 2.069 2.759 .393 .792 1.201 1.857 2.589 4.484 .230 .460 .690 .9201 3/4 .371 .743 1.114 1.486 2.229 2.972 .455 .918 1.393 2.154 3.002 5.200 .248 .495 .743 .990

.390 .796 1.194 1.592 2.388 3.184 .523 1.053 1.599 2.473 3.447 5.970 .266 .531 .796 1.0612 .425 .649 1.274 1.698 2.547 3.396 .594 1.197 1.820 2.813 3.921 6.792 .283 .566 .849 1.132

2 1/4 .478 .955 1.433 1.910 2.865 3.821 .752 1.516 2.303 3.561 4.963 8.596 .318 .637 .955 1.273.530 1.061 1.592 2.123 3.184 4.245 .928 1.871 2.844 4.396 6.127 10.613 .354 .707 1.061 1.415

2 3/4 .584 1.167 1.751 2.335 3.502 4.669 1.123 2.264 3.441 5.319 7.414 12.841 .389 .778 1.167 1.5563 .636 1.274 1.910 2.547 3.821 5.094 1.337 2.695 4.095 6.330 8.823 15.282 .424 .849 1.273 1.698

EQUAL LEGFILLETS

(USE 45°COLUMN)

SINGLEBEVEL

SINGLEV-GROOVE

DOUBLE DOUBLEBEVEL

SINGLE VNO GAP

REINFORCEMENT

GG


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LESSON IX

5. Electrode Cost - $.80/lb (from supplier).

6. Deposition Efficiency - 86% (.86) From Table in Figure 10.

7. Gas Flow Rate - 45 cubic feet per hour. From Figure 7.

8. Gas Cost - $.03/cubic foot (from supplier).

9. Cost of Power - $.045/kWh.

10. Wt/Ft of Weld - From Figure 15B = .846 lbs/ft.

These values are shown inserted into the formulas on the Weld Metal Cost Worksheet in

Figure 16.

9.6 COMPARING WELD METAL COSTS

It is interesting to note that the amount of weld metal deposited in Example 1 and Example 2 is

almost the same, while the total cost of depositing the weld metal is three times higher in

Example 1 as shown below. This is because the flux cored process has a higher deposition

rate, efficiency and operating factor and also allows a tighter joint due to the deep penetrating

characteristics of the process.

Example 1 - 1,280 ft x .814 lbs/ft = 1,041.9 lbs at $13,939

Example 2 - 1,280 ft x .846 lbs/ft = 1,082.9 lbs at $ 4,352

9.6.0.1 When comparing welding processes, all efforts should be made to assure that you

use the proper welding current for the electrode or wire in the position in which the weld must

be made. As an example, consider depositing a given size fillet weld in the vertical-up posi-

45°

22.5° 22.5°

1/16" 7/8"

5/8" 1/2"

1/8"

A B

C

B

B

C

C

1"

1/2"

1/2"

1/16"lbs./ft.

A = .265B = .425C = .124

TOTAL WEIGHT/FT. .814 lbs

lbs./ft.

B = .176 x 4 = .704C = .071 x 2 = .142

TOTAL WEIGHT/FT. .846 lbs

ESTIMATING WELD METAL WEIGHT

FIGURE 15

A B


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LESSON IX

FIGURE 16

EXAMPLE 2WELD METAL COST WORKSHEET

COST PER POUND OF DEPOSITED WELD METAL

LABOR &OVERHEAD

LABOR & OVERHEAD COST/HRDEPOSITION OPERATINGRATE (LBS/HR) x FACTOR

=

ELECTRODE

GAS

FLUX

POWER

ELECTRODE COST/LB

GAS FLOW RATE(CU FT/HR) x GAS COST/CU FT

DEPOSITION RATE (LBS/HR)

FLUX COST/LB x 1.4DEPOSITION EFFICIENCY

COST/kWh x VOLTS x AMPS1000 x DEPOSITION RATE

TOTAL COST PER LB. OFDEPOSITED WELD METAL

SUM OF 1 THROUGH 5 ABOVE

DEPOSITION EFFICIENCY=

=

=

=

1.

2.

3.

4.

5.

6.

7.

8.

30.00

15 x .4530.006.75

4.44= =

.80

.86= .93

= =

x 1.4 = =N A

= =.045 x 31 x 4501000 x 15

627.7515,000

.042

COST PER FOOT OF DEPOSITED WELD METAL

COST PER POUNDOF DEPOSITEDWELD METAL

XPOUNDS PER

FOOT OFWELD JOINT

$ 5.51

= 5.51 x .846 = $4.66

TOTAL FEETOF WELD

=COST PERFOOT

X 1,280x 4.66 = $5,965

COST OF WELD METAL - TOTAL JOB

45 x .031 5

1.351 5

.09


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LESSON IX

tion by the GMAW process and FCAW process semi-automatically. In both processes the

welding current and voltage must be lowered to weld out-of-position, and in GMAW, the short

circuiting arc transfer must be used. Example 3 compares the weld metal cost per pound

deposited by these processes, using the proper current and voltage for depositing a ¼” fillet

weld on ¼” plate, vertically up.

Note: The cost of electrical power is comparable in all processes and therefore, can be eliminated as a factor.

9.6.1 Example 3

FCAW GMAW

Electrode Type - .045” dia. E71T-1 .045” dia. ER70S-3

Labor & Overhead - $30.00/hr $30.00/hr

Welding Current - 180 amperes 125 amperes

Deposition Rate - 4.9 lbs/hr (Fig. 9) 2.8 lbs/hr (Fig. 10)

Operating Factor - 45% (Fig. 2) 50% (Fig. 2)

Electrode Cost - $1.44/lb $.66/lb

Deposition Efficiency - 85% (Fig. 9) 96% (Fig. 6)

Gas Flow Rate - 35 cfh (Fig. 7) 35 cfh (Fig. 7)

Gas Cost Per Cu. Ft. - $.03 CO2 $.11 75% Ar/25% CO2

This data is tabulated in the chart in Figure 17.

9.6.1.1 As you can see, the cost of depositing the weld metal is about 33% less using the

Flux Cored Arc Welding process. Since there is no slag to help hold the vertical weld puddle

in the GMAW process, the welding current with solid wire must be lowered considerably. This,

of course, lowers the deposition rate, and since labor and overhead is the largest factor in-

volved, it substantially raises deposition costs. In the flat or horizontal position, where the

welding current on the solid wire would be much higher, the cost difference would be consider-

ably less pronounced.


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LESSON IX

9.7 OTHER USEFUL FORMULAS

The information discussed below will assist you in making other useful calculations:

TOTAL POUNDS OF ELECTRODES REQUIRED (REF. EXAMPLE 1)

The following information/variables must be determined prior to completing calculations: (1) Proposed Method Cost Calculation (2) Present Method Cost Calculation

Flux Cored Arc Welding Gas Metal Arc WeldingE71T-1 .045 Dia. at 180 Amps (3)

ER70S-3 .045 Dia. at 125 Amps (4) Actual Labor & O/H Rate for your Customer30.00$ Actual Labor & O/H Rate for your Customer 30.00$ Deposition Rate in Pounds per Hour

4.9 Deposition Rate in Pounds per Hour 2.8Operating Factor45% Operating Factor 50%

Electrode Cost per Pound1.44$ Electrode Cost per Pound 0.66$ Deposition Efficiency85% Deposition Efficiency 96%Gas Type

CO2 Gas Type 75% Ar/25% CO2Gas Flow Rate

35 Gas Flow Rate 30Gas Cost per Cubic Foot0.03$ Gas Cost per Cubic Foot 0.11$ Equipment Cost-$

Prepared For: NAME INFO Customer Name: NAME INFO Date:(1) Proposed Method Cost Calculation (2) Present Method Cost Calculation

Result

Formulas for Calculating Flux Cored Arc Welding Gas Metal Arc Welding

(Cost Reduction )

Cost per Pound Deposited Weld Metal E71T-1 .045 Dia. at 180 Amps ER70S-3 .045 Dia. at 125 AmpsCost Increase

Labor& = Labor & Overhead Cost /Hr = $30.00 = $30.00 = $13.605 $30.00 = $30.00 = $21.429 ($7.823 )Overhead Deposition

Rate (lbs / hr) X

OperatingFactor

4.9 X 0.45 = 2.205 2.8 X 0.5 = 1.4

Electrode Electrode Cost/lb = 1.44 = 1.694 0.66 = 0.688 $1.007Deposition Efficiency 0.85 0.96

Gas Type = CO2 Gas Type = 75% Ar/25% CO2

Gas Gas Flow Rate (Cuft/hr)X Gas Cost/Cu ft. = 35 X 0.03 = 1.05 = 0.214 30 X 0.11 = 3.3 = 1.179 ($0.964 )

Deposition Rate (lbs&/hr) 4.9 2.8

Sum of the AboveTotal Variable Cost/lbDeposited Weld Metal = $15.514

Total Variable Cost/lbDeposited Weld Metal = $23.295 ( $7.781)

T otal

Total Pounds =Deposition Efficiency

Wt/Ft of Weld x No. of Ft of Weld

Substituting the values from Example 1:.814 x 1,280

.630= 1,631 lbs

WELDING TIME REQUIRED (REF. EXAMPLE 1)

Welding Time =Wt/Ft of Weld x Ft of Weld

Deposition Rate x Operating Factor

Substituting the values in Example 1: .814 x 1,2805.36 x .30

= 1,0421.608

= 648 Hrs.


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LESSON IX

9.7 OTHER USEFUL FORMULAS

The information discussed below will assist you in making other useful calculations:

TOTAL POUNDS OF ELECTRODES REQUIRED (REF. EXAMPLE 1)

The following information/variables must be determined prior to completing calculations: (1) Proposed Method Cost Calculation (2) Present Method Cost Calculation

Flux Cored Arc Welding Gas Metal Arc WeldingE71T-1 .045 Dia. at 180 Amps (3)

ER70S-3 .045 Dia. at 125 Amps (4) Actual Labor & O/H Rate for your Customer30.00$ Actual Labor & O/H Rate for your Customer 30.00$ Deposition Rate in Pounds per Hour

4.9 Deposition Rate in Pounds per Hour 2.8Operating Factor45% Operating Factor 50%

Electrode Cost per Pound1.44$ Electrode Cost per Pound 0.66$ Deposition Efficiency85% Deposition Efficiency 96%Gas Type

CO2 Gas Type 75% Ar/25% CO2Gas Flow Rate

35 Gas Flow Rate 30Gas Cost per Cubic Foot0.03$ Gas Cost per Cubic Foot 0.11$ Equipment Cost-$

Prepared For: NAME INFO Customer Name: NAME INFO Date:(1) Proposed Method Cost Calculation (2) Present Method Cost Calculation

Result

Formulas for Calculating Flux Cored Arc Welding Gas Metal Arc Welding

(Cost Reduction )

Cost per Pound Deposited Weld Metal E71T-1 .045 Dia. at 180 Amps ER70S-3 .045 Dia. at 125 AmpsCost Increase

Labor& = Labor & Overhead Cost /Hr = $30.00 = $30.00 = $13.605 $30.00 = $30.00 = $21.429 ($7.823 )Overhead Deposition

Rate (lbs / hr) X

OperatingFactor

4.9 X 0.45 = 2.205 2.8 X 0.5 = 1.4

Electrode Electrode Cost/lb = 1.44 = 1.694 0.66 = 0.688 $1.007Deposition Efficiency 0.85 0.96

Gas Type = CO2 Gas Type = 75% Ar/25% CO2

Gas Gas Flow Rate (Cuft/hr)X Gas Cost/Cu ft. = 35 X 0.03 = 1.05 = 0.214 30 X 0.11 = 3.3 = 1.179 ($0.964 )

Deposition Rate (lbs&/hr) 4.9 2.8

Sum of the AboveTotal Variable Cost/lbDeposited Weld Metal = $15.514

Total Variable Cost/lbDeposited Weld Metal = $23.295 ( $7.781)

T otal

Total Pounds =Deposition Efficiency

Wt/Ft of Weld x No. of Ft of Weld

Substituting the values from Example 1:.814 x 1,280

.630= 1,631 lbs

WELDING TIME REQUIRED (REF EXAMPLE 1)


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WELDING TIME REQUIRED (REF. EXAMPLE 1)

Welding Time =Wt/Ft of Weld x Ft of Weld

Deposition Rate x Operating Factor

Substituting the values in Example 1: .814 x 1,2805.36 x .30

= 1,0421.608

= 648 Hrs.

Lesson 10

Reliability of Welding Filler Metals


LESSON IX

9.8 AMORTIZATION OF EQUIPMENT COSTS

Calculations show that you can save $7.00 per pound of deposited weld metal by switching

from E7018 electrodes and the SMAW process to an ER70S0-3 solid wire using the GMAW

process. However, the cost of the necessary equipment (power source, wire feeder and gun)

is $2,800. How long will it take to amortize or regain the cost of the equipment knowing that

the deposition rate of the ER70S-3 is 7.4 lbs/hr and the operating factor of the GMAW process

is 50%? The formula is:

Equipment Cost

$ Savings/Lb(Deposition Rate x Operating Factor) = Man Hrs÷

400 ÷ 3.7 = Man Hrs

Substituting the values in the formula: 2,8007.00 ÷ (7.4 x .50) = Man Hrs

If we divide 108 into eight hour days (108 ÷ 8 = 13.5) the deposited weld metal savings of one

man working an eight hour day for 13-1/2 days will pay for the cost of the equipment.


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TECHNOLOGY


LESSON XRELIABILITY OF

WELDING FILLER METALS




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TABLE OF CONTENTSLESSON X

RELIABILITY OF WELDING FILLER METALS


10.1 INTRODUCTION ...................................................................................... 1

10.2 CODES, SPECIFICATIONS, AND STANDARDS .............................. 1

10.3 THE AMERICAN WELDING SOCIETY ................................................ 2

10.3.1 AWS Filler Metal Specifications ............................................................... 2

10.3.2 AWS Structural Code - Steel .................................................................... 3

10.4 THE AMERICAN SOCIETY FOR TESTING AND MATERIALS ...... 4

10.5 AMERICAN SOCIETY OF MECHANICAL ENGINEERS .................. 4

10.6 SHIP CLASSIFICATION SOCIETIES ................................................... 5

10.6.1 The American Bureau of Shipping ........................................................... 5

10.6.2 Lloyd’s Register of Shipping ..................................................................... 7

10.6.3 Det Norske Veritas .................................................................................... 7

10.7 MILITARY SPECIFICATIONS ................................................................. 8

10.8 STATE HIGHWAY ELECTRODE CERTIFICATION ........................... 9

10.9 TESTING PROCEDURES ...................................................................... 9

10.9.1 Chemical Composition Analysis Test ...................................................... 10

10.9.2 Soundness Test, All-Weld-Metal Tension Test and Impact Test ............ 10

10.9.3 Coating Moisture Test ................................................................................ 13

10.9.4 Guided Bend Tests .................................................................................... 13

10.9.5 Ferrite Test .................................................................................................. 15

10.9.6 Fillet Weld Test ........................................................................................... 16

10.10 CERTIFICATION OF ELECTRODES ................................................... 17

10.10.1 Typical Properties Certification ................................................................ 17

10.10.2 Actual Certifications ................................................................................... 17

10.11 QUALITY ASSURANCE ......................................................................... 19

Appendix A - TEST QUESTIONS .................................................................................. 26


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LESSON X

RELIABILITY OF WELDING FILLER METALS

10.1 INTRODUCTION

Producing a weld by the arc welding process has often been compared to steelmaking on a

very small scale. The weld puddle is molten for a very short time and during that time, a

number of reactions must take place between the base plate, the filler metal, and the

electrode coating or shielding gas ingredients. These reactions must result in predictable

mechanical properties and chemical composition of the weld metal produced by each of

the great number of filler materials available. Reliable welding filler metals are the result of

the proper formulation, adherence to certain codes and specifications, and the result of a

good quality assurance program.

10.2 CODES, SPECIFICATIONS AND STANDARDS

The wide use of welding as a fabricating method requires that certain controls be exercised

to assure the safety and protection of persons and property exposed to structures and

equipment utilizing welded joints. As a result, various codes, specifications and standards

have been established by technical societies and professional organizations to assure safe,

sound welds. Among other things, these groups specify or recommend the base metal

requirements, joint design, filler metal, welding procedures, operator qualifications, required

weld tests, testing methods, and inspection of welds.

10.2.0.1 The professional technical societies or organizations have no way of enforcing

the codes, specifications or standards that they prepare. However, in many instances,

governing bodies of municipalities, counties, states or federal agencies may adopt all or

part of these documents as law. Private industry may require that work performed under

contract will conform to one or more of these codes or specifications, and therefore, they

become part of a legal document. Lastly, purchase orders issued for welding materials

may state that the terms are to meet a particular code or specification, and as such, these

purchase orders have legal implications.

10.2.0.2 The following is a description of the major societies and organizations whose

specifications and codes are widely used in the welding filler metals industry.


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LESSON X

10.3 THE AMERICAN WELDING SOCIETY (AWS)

The AWS publishes a number of specifications, standards and codes that have been

adopted by many governing bodies and industries. The AWS may be considered to be the

basic source of welding and welding engineering information in the USA. Many other

codes and specifications will include or refer to various AWS Filler Metal Specifications.

Electrode and welding filler metal manufacturers assign the appropriate AWS Classification

to their products wherever possible, as a means of standardization, according to the AWS

Filler Metal Specifications. The specifications prescribe the classification requirements

including such items such as chemical composition of the weld metal, radiographic (X-ray)

soundness tests, weld metal tension tests, impact tests, bend tests, and fillet weld tests

where applicable. The following is a complete list of the AWS Filler Metal Specifications for

ferrous and non-ferrous materials.

10.3.1 AWS Filler Metal Specifications

Specification No. Description

A5.1-91 Carbon Steel Covered Arc Welding Electrodes

A5.2-92 Iron & Steel Oxy Fuel Gas Welding Rods

A5.3-91 Aluminum & Aluminum Alloy Covered Electrodes

A5.4-92 Corrosion Resisting Chromium & Chromium-Nickel Steel

Covered Electrodes

A5.5-96 Low Alloy Steel Covered Arc Welding Electrodes

A5.6-84 Copper & Copper-Alloy Covered Electrodes

A5.7-84 Copper & Copper-Alloy Bare Welding Rods & Electrodes

A5.8-92 Brazing Filler Metals

A5.9-93 Corrosion-Resisting Chromium & Chromium-Nickel Steel

Bare & Composite Metal Cored &

Stranded Electrodes & Welding Rods

A5.10-92 Aluminum & Aluminum Alloy Bare Welding Rods & Electrodes

A5.11-90 Nickel & Nickel Alloy Covered Welding Electrodes

A5.12-92 Tungsten Arc Welding Electrodes

A5.13-80 Solid Surfacing Welding Rods & Electrodes

A5.14-89 Nickel & Nickel-Alloy Bare Welding Rods & Electrodes

A5.15-90 Welding Rods & Covered Electrodes for Welding Cast Iron

A5.16-90 Titanium & Titanium Bare Welding Rods & Electrodes


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LESSON X


A5.17-89 Carbon Steel Electrodes & Fluxes for Submerged ArcWelding

A5.18-93 Carbon Steel Filler Metals for Shielded Arc Welding

A5.19-93 Magnesium Alloy Welding Rods & Bare ElectrodesA5.20-95 Carbon Steel Electrodes for Flux Cored Arc Welding

A5.21-80 Composite Surfacing Welding Rods & Electrodes

A5.22-95 Flux Cored Corrosion Resistant Chromium &Chromium-Nickel Steel Electrodes

A5.23-90 Low Alloy Steel Electrodes & Fluxes for Submerged Arc

WeldingA5.24-90 Zirconium & Zirconium Alloy Bare Welding Rods &

Electrodes

A5.25-91 Consumables for Electroslag Welding of Carbon & HighStrength Low Alloy Steels

A5.26-91 Consumables for Electrogas Welding of Carbon & High

Strength Low Alloy SteelsA5.27-85 Copper and Copper Alloy Rods for Oxyfuel Gas Welding

A5.28-96 Low Alloy Steel Filler Metals for Gas Shielded Arc

WeldingA5.29-98 Low Alloy Steel Electrodes for Flux Cored Arc Welding

A5.30-79 Consumable Inserts

A5.31-92 Fluxes for Brazing and Braze Welding

10.3.1.1 These filler metal specifications also describe the classification requirements

concerning standardization such as electrode size and length, packaging, spooling, mark-

ing, labeling, and others.

10.3.2 AWS Structural Welding Code - Steel - The AWS Structural Welding Code -

Steel (AWS D1.1-96) covers the welding requirements applicable to welded steel structures

including buildings, bridges, and structures consisting of tubular shaped members. Factors

such as the design of welded connections, workmanship, welding procedure, welding

operator qualification, and inspection requirements are covered in this code. Previous to

the 1994 issue of this code, it also specified the tensile strength, yield strength, elongation,

and impact requirements for the low alloy flux cored electrodes, since no AWS Filler Metal

Specification existed for these electrodes. It is required that the user (contractor or fabrica-

tor) conduct tests to show that the low alloy weld metal would meet the mechanical proper-

ties mentioned above per the code.


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LESSON X

10.3.2.1 With the issuance of AWS A5.29-80, Specification for Low Alloy Steel Electrodes

for Flux Cored Arc Welding, the user now need only furnish the electrode manufacturer’s

certification that his product will meet the classification requirements of the latest edition of

AWS A5.29.

10.3.2.2 The AWS Structural Welding Code (AWS D1.1-96) does not prescribe such

design details as the location of parts or stress calculations to determine the size of

load-carrying members in a structure. These details will be covered in a general Building

Code that might state, “This structure is to conform to the American Institute of Steel

Construction (AISC) Specification for the Design, Fabrication and Erection of Structural

Steel For Buildings, and the AWS Structural Welding Code, AWS D1.1.” In this case, the

AWS Structural Welding Code becomes a part of a general building code that may be

adopted by a governing body.

10.3.2.3 The AWS publishes other specifications, standards and recommended practices

covering the welding of automotive parts, construction equipment, machinery, ships, and

water storage reservoirs. These, however, are less concerned with filler metal specification

and selection than they are with welding techniques, procedures, and operator qualifica-

tion.

10.4 AMERICAN SOCIETY FOR TESTING AND

MATERIALS (ASTM)

The main objectives of the American Society For Testing & Materials are (1) to further the

knowledge of many types of materials, and (2) establish standardized specifications of and

standardized test methods for these materials.

10.4.0.1 The chemical and mechanical tests that apply to welding filler metals, as de-

scribed by the AWS and other professional organizations, are often based on the ASTM

standard testing methods.

10.5 AMERICAN SOCIETY OF MECHANICAL

ENGINEERS (ASME)

The ASME is instrumental in establishing many codes and specifications. TheASME Boiler & Pressure Vessel Code is of primary importance for welding materials and

applications. This code is extensive, and is published in several different sections. Those

parts that refer to welding filler metals and welding requirements are:


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LESSON X

Section I. Power Boilers

Section II. Material Specifications

Section III. Nuclear Vessels

Section IV. Low Pressure Boilers

Section VIII. Unfired Pressure Boilers

10.5.0.1 Section II of the code, in which welding filler metals are specified, states that the

ASME has adopted the AWS Filler Metal Specifications verbatim (word for word). How-

ever, they do have their own specification designation. For example, AMSE SFA 5.5-96

Specification for Low Alloy Steel Covered Arc Welding Electrodes is the same as AWS

A5.5-96.

10.5.0.2 Under Section III of the code, the ASME issues a Quality System Certificate to

manufacturers of materials (including welding electrodes and wire) to be used under the

code. This certificate is issued only after an ASME plant audit and the manufacturer’s

entire quality assurance program is approved. Its issuance allows the manufacturer’s

products to be used in boiler and pressure vessel work, as well as on nuclear applications

as specified in the code. Details of the Quality System Certificate will be covered under the

Quality Assurance Section of this lesson.

10.6 SHIP CLASSIFICATION SOCIETIES

10.6.1 The American Bureau of Shipping (ABS) - The ABS is a non-profit, interna-

tional ship classification society. It certifies the structural integrity and mechanical fitness of

merchant ships, offshore drilling rigs, and other marine structures.

10.6.1.1 Annually, the Bureau publishes a listing entitled “Approved Welding Electrodes,

Wire-Flux and Wire-Gas Combinations.” The approvals of the filler metals are based upon

tests conducted to standards established by the Bureau or by other recognized agencies.

As requested by the manufacturer, filler metals may be approved to an AWS Filler Metal

Specification, and so listed, or approved to an ABS Grade as shown in Figure 1. In either

case, the approval testing must be made in the manufacturer’s facility in the presence of an

ABS representative. The extent of testing will vary, depending on the type of weld for which

the product is being qualified (fillet or butt), whether the filler material is being initially tested

as a new product, being tested annually, or whether the product is being upgraded at the

manufacturer’s request.

10.6.1.2 At the time of annual testing, the manufacturing facilities and quality control

procedures are subject to inspection also.


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68


LESSON X

10.6.1.3 Following are the various grade designations as assigned by the ABS.

MANUAL ELECTRODES FILLER METAL GRADES (SMAW)

Ordinary Strength 1 1Y

2 2Y

3 3Y

2H (Low Hydrogen)

3H (Low Hydrogen)

WIRE AND WIRE-GAS COMBINATION FILLER METAL GRADES (GMAW FCAW)

Ordinary Strength Higher Strength

1SA, 1A, 1T 1YSA, 1YA, 1YT



ABS FILLER METAL GRADING SYSTEM

FIGURE 1

TENSILESTRENGTH

YIELDSTRENGTH

ELONGATION 2"

ABSGRADE

1 2

IMPACT°F

68 32 14 -4 50 32 32 14 -4 14 -4 -22 -40

FT/LBS.MANUAL

SEMI-AUTO35 35 45 35 40 – 20 40 – 20 50 40 – 20

FT/LBS.AUTOMATIC 25 25 33 25 30 20 – 30 20 – 38 30 20 –

1,2,3 (see above) T Two pass automaticY Higher strength & impacts S Semi-automatic onlyH Low hydrogen electrode A Automatic onlyM Multi-pass automatic SA Semi-auto or automatic

20% MIN.

ORDINARY STRENGTHABS FILLER METAL

HIGHER-STRENGTH ABS FILLER METAL

58,300TO

95,100 psi

71,000 TO

95,000 psi

Note: Where more than one test temperature is indicated for a specific grade, satisfactory testing according to any indicated temperature isacceptable.

GRADE NOTATIONS

ABS FILLER METAL MECHANICAL PROPERTY REQUIREMENTS

3 1Y 2Y 3Y

44,100 psi MIN. 54,000 psi MIN.

22% MIN.


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LESSON X

WIRE-FLUX COMBINATION FILLER METAL GRADES (SAW)

Ordinary Strength Higher Strength

1TM, 1T, 1M 1YTM, 1YT, 1YM



10.6.1.4 By using the table and grade notations in Figure 1, you can see that the grade

ABS 2YSA signifies: (2Y) a tensile strength in the 71,000-95,000 psi range, a minimum

yield strength of 54,000 psi, and a minimum elongation of 20% in 2 inches, meets the

impact requirements of 20 ft.-lbs. at -4°F when welded semi-automatically, and 20 ft.-lbs. at

14°F when welded automatically: (SA) the wire-gas combination has been approved for

semi-automatic and automatic welding.

10.6.1.5 In the annual ABS Listing, the approved electrode or wire diameter, welding

position, shielding gas (if applicable) and type of welding current (AC or DC) are also listed.

Each electrode or filler metal must be re-approved annually.

10.6.2 Lloyd’s Register of Shipping (LRS) - Lloyd’s Register of Shipping is a British

ship classification society similar to the ABS. They also publish an annual approved filler

metal listing with test procedures very similar to the ABS.

10.6.3 Det Norske Veritas (DNV) - Det Norske Veritas is a Norwegian ship classifica-

tion society that operates very similarly to the American Bureau of Shipping and Lloyd’s

Register.

10.6.3.1 ESAB has a number of filler metals on the approved list of each of the three ship

classification societies. Since the listings change annually, they do not appear in this

instructional material. Information on the listings of any specific product may be secured by

contacting the Technical Services Department.


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LESSON X

10.7 MILITARY SPECIFICATIONS

Military specifications are issued by the Department of Defense and it is mandatory that all

work performed for that department be covered by the applicable military specification.

Military specifications are identified by a letter-number designation and the title. An ex-

ample is: MIL-E-22200/1E - Electrodes, Welding , Mineral Covered, Iron Powder, LowHydrogen, Medium and High Tensile Strength, As-Welded or Stress Relieved Applications.

10.7.0.1 In the example, MIL designates that it is a Military specification. The first letter E

stands for Electrode which is the significant word in the title. The number 22200/1 is the

serial number of the specification; the letter E at the end designates the revision letter and

will change as further revisions are made. The underlined portion is the title of the specifi-

cation.

10.7.0.2 A Military specification may cover only one or a number of electrodes or wires.

When the specification includes more than one item, a “type” designation is necessary. As

an example, an E8018-C3 low alloy electrode would be designated as MIL-E-22200/1E,

MIL 8018-C3.

10.7.0.3 The following is a partial list, along with a brief description, of the more common

military electrode specifications currently in use.


QQ-E-450a Covered Mild Steel Electrodes

MIL-E-13080 Covered Austenitic Steel Electrodes for Armor

Application

MIL-E-16053L Bare Aluminum Alloy Wires

MIL-E-16589 Covered Chrome-Molybdenum and Corrosion Resisting Steel

MIL-E-19933 Bare Chrome-Nickel Stainless Steel Wire

MIL-E-21562 Bare Nickel-Alloy Wires

MIL-E-22200/1F Covered, Iron Powder, Low Hydrogen, Medium and High

Tensile Steel Electrodes

MIL-E-22200/2C Covered Electrode, Austenitic Stainless Steel for

Corrosion and High Temperature Service

MIL-E-22200/3F Covered Electrode, Nickel-Base and Cobalt-Base Alloy

MIL-E-22200/4C Covered Electrode, Copper-Nickel Alloy

MIL-E-22200/5B Covered, Iron Powder, Low Hydrogen, Low Alloy Steel for

Hardening & Tempering

MIL-E-22200/6C Covered Electrode, Low Hydrogen, Medium and High Tensile

Steel


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LESSON X

MIL-E-22200/7B Covered Electrode, Molybdenum Alloy Electrodes

MIL-E-22200/8B Covered Electrode, Low Hydrogen, and Low Hydrogen Iron

Powder Alloy Steels and Corrosion Resisting Steels

MIL-E-22200/10B Covered, Iron Powder, Low Hydrogen, Medium and High

Tensile Steel Electrodes

MIL-E-23765/B (SH) Bare Solid Mild Steel Wires

MIL-E-24403/A (SH) Flux Cored Electrodes

MIL-E-19933E (SH) Bare Solid Chromium and Chromium-Nickel Steels

10.7.0.4 Some military specifications require varying degrees of testing by the manufac-

turer before a filler metal is submitted for use. These tests and testing procedures are

spelled out in the specification, and when successfully completed, the electrode or wire is

placed upon a Qualified Products List (QPL). Other specifications require the manufacturer

to submit an affidavit indicating the success of the testing of each specific shipment.

10.8 STATE HIGHWAY ELECTRODE CERTIFICATION

Electrodes and filler metals are approved for bridge and highway construction according to

the Federal Highway Administration Requirements. Electrodes are tested, and certification

is renewed annually to those states that maintain an approved list meeting Federal require-

ments. These listings vary annually, and the manufacturer should be consulted for verifica-

tion.

10.9 TESTING PROCEDURES

Test of welding filler metals per the specifications of the various societies, professional

organizations and governing bodies is time-consuming and expensive. However, accurate

testing is an important factor in producing quality welding filler metals. Test plates must be

welded according to the procedure stated in the specification, which in many instances

requires controlled preheat and interpass temperatures. The specimens must be carefully

machined from the proper portion of the test plate and held to very close dimensional

tolerances so that test results will be accurate. The test equipment must be kept in accu-

rate calibration.

10.9.0.1 The following are brief, partial descriptions of the more common types of tests

required by various specifications and codes. They are shown here to familiarize you with

the methods by which tests are conducted and are not to be construed as complete test

procedures.


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LESSON X

10.9.1 Chemical Composition Analysis Test - A weld pad for determining the chemi-

cal composition of a filler metal must be prepared as shown in Figure 2.

10.9.1.1 The base metal size and material is specified, and the weld metal is built up in

layers to the required height or number of passes to assure that the top surface has no

dilution with the base metal. The welds are deposited in the flat position. After welding, the

top surface is machined or ground smooth to remove all foreign matter. A sample is taken

from this surface for chemical analysis by a suitable method agreed upon between the

supplier and the purchaser.

10.9.2 Soundness (X-Ray) Test, All-Weld-Metal Tension Test and Impact Test - A

test plate is prepared according to the specification with a sufficient number of passes to fill

the groove, a sample of which is shown in Figure 3.

10.9.2.1 Some specifications require at least one stop and one start in the area of the

weld that is to be radiographed (X-rayed). The specification may also call for the test plate

to be preheated to a certain temperature before the first pass, and also specify an

interpass temperature. This means that the test plate must be allowed to cool to a certain

temperature range before the next pass is applied.

10.9.2.2 After the plate is completely welded, the test plate is prepared for radiographic

examination by machining off the backing strip from the root (bottom) of the weld, and also

TYPICAL WELDPAD FORCHEMICAL COMPOSITION ANALYSIS

Figure 2

CHEMICAL COMPOSITION SAMPLETAKEN FROM THIS SURFACE

SPECIFIED BY NUMBER OFLAYERS IN SOME SPECIFICATIONS


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LESSON X

the reinforcement or excess weld metal from the top (face) of the weld. The plate is then

radiographed to check for porosity or inclusions in the weld metal. The specification will

show several degrees and grades of acceptable porosity or inclusions.

10.9.2.3 Porosity and inclusion diagrams, as shown in Figure 4, are usually labeled as

fine, medium, assorted, and large. A representation of fine and large porosity is shown in

Figure 4. The allowable amount of porosity may vary for different filler metal specifications.

ALL WELD METAL TENSION SPECIMEN V-NOTCH IMPACT TEST SPECIMEN

DETAILS OF TEST ASSEMBLY FOR SOUNDNESS, TENSILE AND IMPACT TESTS

Figure 3


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LESSON X

10.9.2.4 After the test plate has been radiographed, the all-weld-metal tension specimen,

and the charpy V-notch impact specimen are machined from the center of the plate as

shown in Figure 3. Only the critical dimensions are shown in the sketches, and as you can

see, they must be held to rather close tolerances to obtain accurate test results.

10.9.2.5 The .500± .010" diameter of the tension specimen is all weld metal since it is

machined from the center of the weld. The area of the impact specimens in which the

notch is machined is all weld metal also.

10.9.2.6 The tensile specimen is placed in a tensile testing machine and pulled until it

fractures. (Refer to Lesson I, "Yield Strength".) The yield strength and ultimate tensilestrength are recorded on the tensile tester. After fracture, the two halves of the broken

specimen are fitted back together in a jig, and the distance between the two center punch

marks is accurately measured. If this distance is now 2.500", it tells us that the specimen

has stretched .500" or 25% of its original length before breaking. This figure is recorded as

the elongation in a 2" length of the weld metal specimen.

10.9.2.7 The five impact specimens are broken in a Charpy Impact Tester, as described in

Lesson I, "Charpy Impacts", and the energy absorbed in breaking each of them is re-

corded. In calculating the average impact value, the specimens with the highest and low-

est values are discarded. The average value of the three remaining specimens is recorded

as the impact value.

LARGE POROSITY OR INCLUSIONS3/64" to 1/16" DIAMETER OR LENGTH

MAXIMUM NUMBER IN ANY 6" OF WELD = 8

FINE POROSITY OR INCLUSIONS1/64" to 1/32" DIAMETER OR LENGTH

MAXIMUM NUMBER IN ANY 6" OF WELD = 30

SOUNDNESS TEST POROSITY AND INCLUSION STANDARDS

Figure 4


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LESSON X

10.9.3 Coating Moisture Test - The coating moisture test is conducted by removing a

small amount of the coating from the middle portions of three electrodes, all from the same

can or package. A small measured amount (4 grams) of this coating sample is tested in

sophisticated laboratory apparatus. The method of moisture testing satisfies AWS A5.5-96

and AWS D1.1 Specifications and is sensitive only to water. It is the most accurate and

reliable method of moisture determination currently in use.

10.9.4 Guided Bend Tests -

10.9.4.1 Transverse Face Bend, Root Bend and Side Bend Tests. The specifications for

some filler metals require that guided bend tests be made to evaluate the ductility and

soundness of a welded joint. The test plate is welded in the flat position and is made long

enough to produce the necessary number of specimens. See Figure 5.

10.9.4.1.1 The specimens are cut from the test plate, and the backing strip and weld

reinforcement machined flush with the face and root surfaces. If the test plate is greater

than 3/8" thick, it must be machined to 3/8" thickness, removing the metal from the root

surface for face bends, and from the face surface for root bends. In face bends, the face

of the weld is on the outside or convex surface of the specimen, and in root bends, the root

of the weld is on the outside or convex surface of the bend. The specimen is bent in a

guided bend test jig, the design of which is described in the specification, over a justified

radius (usually a 3/4" radius) through an angle of 180°. When removed from the jig, the

TRANSVERSE GUIDED BEND TESTSFIGURE 5

FACE OR ROOT BEND TEST SIDE BEND TEST PLATE

FACE BEND ROOT BEND SIDE BEND


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LESSON X

specimen will spring back to about the angle shown in Figure 5. In face and root bends,

defects in the surface of the weld are exposed as cracks, tears, or porosity.

10.9.4.1.2 Side bend tests are similar to face and root bend tests, except they are bent

so the side of the weld is on the outside or convex surface of the specimen. Side bends

expose defects in the interior and fusion zone of the weld.

10.9.4.2 Transverse Tension and Longitudinal Guided Bend Test. The transverse tension

test and longitudinal guided bend test may appear separately in some specifications; how-

ever, it is shown here (Figure 6) as they appear in AWS A5.20-95 (applicable only to the

single-pass electrodes of the E70T-2, E70T-3, E70T-10, and E70T-GS classifications.)

DETAILS OF TRANSVERSE TENSION AND GUIDED BEND TESTSFIGURE 6

10.9.4.2.1 An all-weld-metal tensile test, as shown in Figure 3, would not be meaningful

for single-pass electrodes because in single-pass welds, the weld metal is always substan-

tially diluted with the base metal. The bend test is prescribed for these electrodes because

they contain relatively high amounts of manganese and silicon that can reduce ductility

somewhat, and can cause cracking in the weld area when present in excessive amounts.


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LESSON X

10.9.4.2.2 The test plate must be a material having a minimum tensile strength equal to

that of the electrode being tested. The test plate is welded with one weld bead on each

side of the plate. This is considered a single-pass weld since each weld will be diluted with

the base material. The tensile specimen is cut from the plate, machined to the shape

shown in Figure 6, and pulled until fractured. A specimen that breaks in the base plate

shall be considered satisfactory.

10.9.4.2.3 The weld beads on the bend specimens are ground or machined smooth and

flush with the surface. The specimen is then uniformly bent over a 3/4" radius through an

angle of 180° in a suitable jig. The specimen, after bending, may show no crack exceeding

1/8" in length in any direction in the weld metal or the base metal.

10.9.5 Ferrite Test - In austenitic stainless steels, ferrite (as discussed in Lesson V) can

be beneficial in reducing cracking in some stainless steel weld metals, while in other envi-

ronments, it can reduce corrosion resistance. It can cause brittleness in high temperature

service, and can reduce toughness in cryogenic service. For these reasons, the amount of

ferrite in austenitic stainless steel weld metal must be established as accurately as pos-

sible. Ferrite content can be calculated by using the Schaeffler diagram or the WRC dia-

gram as shown in Lesson V, when the chemical analysis of the weld metal is known. It can

also be determined by the use of various magnetic sensing instruments.

10.9.5.1 To determine the ferrite level by instrument, a weld pad, as shown in Figure 7,

must be made.

10.9.5.2 The copper bars are used as a mold or form to build up the weld metal to the

proper height as shown. The welding procedure used in preparing test pad is carefully

spelled out in the specification as to welding direction, stops and starts, cleaning and

WELD PAD PREPARATION FOR FERRITE TEST

Figure 7

WELDDEPOSIT

1/2" TO 5/8"MINIMUMHEIGHT


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LESSON X

interpass temperature. The top surface of the completed pad is carefully filed by hand in

the direction of the weld. Six readings are taken along the top of the weld pad with a prop-

erly calibrated magnetic instrument. The six readings are averaged to a single value. This

average becomes the ferrite number.

10.9.6 Fillet Weld Test - Some specifications require the fillet weld test be prepared as

shown in Figure 8.

10.9.6.1 The weld specimen is made using the specified electrode size and plate thick-

ness. After welding, the plate is cut on the lines indicated, and one side of the 1" wide

section is polished and etched so that the weld bead is clearly visible. The largest possible

right triangle with equal leg lengths is carefully scribed within the fillet weld on this surface,

so that the fillet size, leg lengths, and convexity of the weld can be measured and com-

pared to the allowable deviations in the specification.

10.9.6.2 The welds in the two longer sections are broken by applying a force in the direc-

tion shown in the diagram. The broken surfaces are visually examined for evidence of

inclusions, gas pockets, or incomplete root fusion.

10.9.6.3 Fillet weld tests are especially required for all-position electrodes or wires, and

the specification will require that the test plates be welded in the vertical-up and overhead

positions.

FILLET WELD TEST SPECIMENFigure 8

LEG

CONVEXITY

LEG


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LESSON X

10.10 CERTIFICATION OF ELECTRODES

The certification of electrodes and welding wires has become more critical today, and the

number of test certifications requested has increased more than ten-fold in the last several

years. Conducting certification tests is a costly process, and all efforts must be made to

provide accurate information to the manufacturer, so that the end-user gets the material

tested to the necessary degree; no more, no less.

10.10.0.1 Welding filler metals may be certified by one of two methods: typical properties

certification or actual properties certification.

10.10.1 Typical Properties Certification - Certifications showing typical chemistry and

mechanical properties are provided with customer orders when so requested. These

typical properties are based on the results of many tests on similar materials and on a very

comprehensive, carefully controlled Quality Assurance System. An ESAB Typical Proper-

ties Certificate assures that the

products are tested in compliance

with AWS and ASME Filler Metal

Specifications. A copy of a Typical

Properties Certificate for Atom Arc

electrodes is shown in Figure 9.

Typical certifications are supplied by

the manufacturer, on a no-charge

basis, by request.

10.10.2 Actual Certifications -

Actual certification that each lot of a

particular product shipment will

meet a desired specification is

normally supplied by the manufac-

turer for a fee. In this case, pack-

ages of each lot number of the

product to be shipped will be

opened and tested according to the

customer’s request.

TYPICAL PROPERTIES CERTIFICATE

FIGURE 9


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LESSON X

10.10.2.1 In order to have the proper tests performed correctly and as inexpensively as

possible, the information that accompanies the order must contain all pertinent information

such as:

a. To what specification must the material conform and to what revision of that

specification?

b. Must all the tests as required by the specification be performed?

c. Are there any actual tests required in addition to those covered by the specifica-

tion?

d. Do special marking and packing requirements apply?

e. Is the material for a government contract?

f. Where is inspection to be performed and by whom?

g. What number of copies and distribution method is required for the certificates?

10.10.2.2 The American Welding Society publishes a document (AWS A5.01-93) entitled

“Filler Metal Procurement Guidelines”. This document (together with an AWS Filler Metal

Specification) is intended to assist the buyer in designating those testing requirements that

are applicable to his order. It consists of the following:

a. The AWS Filler Metal Classification.

b. Definition of lot classification (AWS A5.01-93 Section 2).

c. The intensity of testing schedule (i.e., number of tests to be conducted) (AWS

A5.01-93 Section 3).

10.10.2.3 A portion of Table 1, “Intensity of Testing” that applies to actual testing reads as

follows:

Intensity of Testing

Schedule

H Chemical analysis only for each lot shipped.

I Tests called for in Table 2 “Required Tests” for each lot shipped.

J All tests that the classification called for in the pertinent AWS filler metal

specifications for each lot shipped.

K All tests specified by the purchaser, for each lot shipped.


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LESSON X

10.10.2.4 Table 2, referred to in Schedule I above, lists the “Required Tests” necessary

for actual certification, and in all cases, does not include all tests included in the applicable

AWS Filler Metal Specification. When the intensity of testing is not specified on an order,

the product will be tested to ESAB standard testing intensity which equals or exceeds those

tests required under Schedule I above.

10.10.2.5 As an example, stainless steel covered electrodes will only be tested for (1)

chemical analysis and (2) calculated ferrite content as required by the AWS Filler Metal

Procurement Guidelines A5.01-93. Any additional testing must be specified.

10.11 QUALITY ASSURANCE

ESAB has based its Quality Assurance Program around NCA 3800 of the ASME Boiler and

Pressure Vessel Code, Section III. This means that the program assures accurate docu-

mentation, close control of the raw materials including the steel and flux ingredients,

in-process controls and checks, and complete traceability of each lot of product produced.

It also includes close control of the inspection and measuring equipment which assures

accurate testing and certification of test results.

10.11.0.1 Both the Hanover, Pennsylvania and Ashtabula, Ohio Quality System Programs

have been accepted by the ASME as material manufacturers. This means that customers

using our products for nuclear and other applications to ASME requirements need not audit

our Quality Program. Copies of the ASME Quality System Certificates for both plants are

shown in figures 10 and 11. These certificates are issued only after an in-plant audit by an

ASME representative, and are valid for a three year period.

10.11.0.2 In addition, facilities in Hanover, PA; Ashtabula, OH; Niagara Falls, NY; and

Monterrey, Mexico have been certified to ISO 9002. This quality standard was first estab-

lished in 1987 by the International Organization for Standardization in Geneva, Switzerland.

Certification to this standard covers all areas of product manufacturing, including general

management, production, research, purchasing, engineering, human resources, and quality

assurance. Receipt of this certificate eliminates the costly time consuming audits normally

required by our customers. Copies of these certificates are shown in figures 12 through 15.


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LESSON X

QUALITY SYSTEM CERTIFICATE, ESAB HANOVER

FIGURE 10


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QUALITY SYSTEM CERTIFICATE, ESAB ASHTABULA

FIGURE 11


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LESSON X

ISO 9000 CERTIFICATION - ESAB HANOVER

FIGURE 12


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LESSON X

ISO 9000 CERTIFICATION - ESAB ASHTABULA

FIGURE 13


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LESSON X

ISO 9000 CERTIFICATION - ESAB Niagara Falls

FIGURE 14


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LESSON X

ISO 9000 CERTIFICATION - ESAB MonterreyFIGURE 15


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