Hardenable Boron Steel

5/22/2018 Hardenable Boron Steel

1/8

Hardenable boron steelHardenable boron steel grades B 13S, B 24 and B 27 are intended to be hardened through heat treatment. The mechanical

properties of hardened boron steel make it extremely resistant to abrasive wear and particularly useful in high-strength

structural applications, extending the lifespan of structures and saving costs related to abrasion and the environment.

Delivered in hot-rolled condition as cut lengths and heavy plates. Prefabrication services available for boron steels are

shape cutting, bending, bevelling for welding.

Applications:

Linings and wear parts for machines and equipment

Edge plates

Blades and chains

Tools

Screw conveyors

Wear plates

Fan blades

The information on our web site is accurate to the best of our knowledge and understanding. Although every effort has been made to ensureaccuracy, the company cannot accept any responsibility for any direct or indirect damages resulting from possible errors or incorrect

application of the information of this publication. We reserve the right to make changes.

Copyright 2014 Rautaruukki Corporation. All rights reserved.

Document printed on 22.07.2014 www.ruukki.com


2/8

Dimensions

Product shapes

Cut lengths. Delivered in as-rolled condition or pickled condition. Additionally, coils and slit strips by separate agreement.

Heavy plates. Delivered in as-rolled condition or shop-primed condition.

Cut lengths with mill edges

Steel grade Thickness mm Width mm Length m

B 13S, B24, B27 2 .5 - 13 1000 - 1860 2 - 12

Maximum width of each steel grade depends on the thickness.

Heavy plates

Steel grade Thickness mm Width mm Length m

B 13S 5 - 14 1901 - 3300 2 - 15

B 24 8 - 60 1901 - 3300 2 - 15

B 27 6 - 80 1901 - 3300 2 - 15

Maximum and minimum width as well as maximum length of each steel grade depend on the plate thickness.

More detailed information on dimensions is provided in the Coil Products Production Programme and Plate Products

Production Programme. Coil Products Production Programme Plate Products Production Programme

Tolerances

Dimensional and shape tolerances:

Cut lengths: EN 10051

Heavy plates: EN 10029, Class A

Surface quality

Plate products: EN 10163-2 Class A3. Repair welding is not used in the manufacture of boron steels.

Cut lengths are delivered in as-rolled condition or pickled and oiled condition.

Plates are delivered in as-rolled or shop-primed condition.

Properties

The numbers 13, 24 and 27 in the designation refer to the average carbon contents in one hundredth of a per cent in

these grades. Excellent heat treatment properties make boron steel an environmentally friendly structural material for a

number of applications.

Materials testing

The mechanical properties of boron steels are not tested.

Hardenable boron steel

2


3/8

Typical mechanical properties

Steel grade Yield strengthReHMPa

Tensile strengthRmMPa

ElongationA5%

Hardness HBW

B 13S approx. 450 approx. 570 25 approx. 160

B 24 approx. 400 approx. 600 25 approx. 160

B 27 approx. 420 approx. 620 22 approx. 170

Chemical composition and microstructure

The typical microstructure in the hot-rolled condition is ferritic-perlitic. Boron (on average 0.002%) and carbon are the alloy

materials mainly contributing to the good hardenability and heat treatment properties of boron steels.

Typical chemical composition. Content % (cast analysis)

Steel grade C Si Mn Cr Mo B

B 13S 1) 0.13 0.25 0.80 0.9 0.25 0.002

B 24 0.24 0.25 1.20 0.3 0.002

B 27 0.27 0.25 1.20 0.3 0.002

Aluminium (Al) and/or titanium (Ti) are used as micro alloying elements for the binding of nitrogen (N).1) For cut length C = 0.14 Si = 0.20 Mn = 1.10 Cr = 0.8 and B = 0.002.

Carbon equivalent (CEV), typical values for each thickness range and product form

CEV = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15

Steel grade Thickness mm CEV Product

B 13S 2.5 - 13 0.51 Cut length

B 24 2.5 - 13 0.51 Cut length

B 24 8 - 60 0.51 Plate

B 27 2.5 - 13 0.54 Cut length

B 27 6 - 80 0.54 Plate

In order to optimise the welding procedure, the cast-specific carbon equivalent values are indicated in the inspection document.

Prefabrication services

Wide flats from plate and strip

Wide flats from plate and strip are dimensionally accurate and ready for assembly. Wide flats speed up the manufacture of

steel structures and avoid wasting of material.

Flat cut shapes

Flat cut shapes will decrease the throughput time of installation. The customer will receive the components ready for

installation. So, unnecessary material and storing costs can be avoided. If ordered, the products are delivered as shop-

primed, bevelled and bent.


3


4/8

Bevelling

Precision cut lengths and precision cut plates with a bevelled edge are components that can be delivered directly to the

installation site, which saves time and reduces transport and storage costs. The dimensionally accurate groove ensures

uninterrupted automated welding and fitting.

Bent plate products

Bent plate products are components that are ready to be delivered to the installation site, which is beneficial in terms of

schedule as well as transport and storing costs. If needed, the products can be ordered as shop-primed, furnished with

welding bevels, and cut to shape. Premarked matchmarks facilitate installation.

Processing instructions

Welding

Boron steels can be welded in the hot-rolled or hardened condition. When choosing the welding consumables, the most

important factor is whether the steel is to be welded before or after hardening. In all cases, the use of low hydrogen, basic

filler materials is recommended, in order to ensure that the level of detrimental hydrogen remains low. The surfaces of the

weld groove must be dry and clean. In addition, the recommendations of the manufacturer must be adhered to regarding

the storage, use and possible re-drying of the consumables.

Welding before hardening

The normal instructions for the welding of high-strength steels also apply in the welding of boron steels in the hot-rolled

condition. The best result is obtained using low-hydrogen welding consumables and methods. The best result is obtained

when the weld metal hydrogen content HD is a maximum of 5 ml/100g (EN ISO 3690).

Carbon equivalent (CEV), typical values for each thickness range and product form

CEV = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15

Steel grade Thickness mm CEV Product

B 13S 2.5 - 13 0.51 Cut length

B 24 2.5 - 13 0.51 Cut length

B 24 8 - 60 0.51 Plate

B 27 2.5 - 13 0.54 Cut length

B 27 6 - 80 0.54 Plate


4


5/8

Recommended working temperatures for welding of hot-rolled boron steels C (EN1011-2)

The advantages of common low-alloy welding consumables compared to the high-alloyed and high-strength welding

consumables are their lower hardenability, reduced need for preheating and lower price. When hardened, the weld metal

produced using normal filler materials is almost as hard as if using high-strength filler materials, but the depth of the

hardening smaller. High- alloyed consumables must be used when a deep hardenable weld metal is required, or when wear

resistance is required from the filler material in the welded condition. The use of high-alloyed consumables can usually be

limited to the surface layers. The wear of soft filler materials may be reduced by the location of the weld.

Welding after hardening

The welding instructions given for Raex abrasion resistant steels in the Raex datasheet can be used in the welding of

hardened boron steels. Raex 400 can be used for hardened B 13S and hardened B 24 and Raex 500 for hardened B 27.

When welding boron steels in the hardened condition, a narrow band of material softer than the base material is created in

the heat affected zone. The width and hardness of this band depends on the welding energy and the thickness of the plate.

The softer band in welds made using medium energy levels does not usually affect the durability of the weld. Low-hydrogen,

basic consumables must be used in order to ensure that the level of detrimental hydrogen remains low. Structures welded

after hardening are not usually subjected to further heat treatment as this may weaken the abrasion resistance of hardened

steel components.

Download information about welding hot-rolled steels

Heat treatment, hardening and tempering

Thanks to their specific alloying, boron steels have a variety of metallurgical properties that can be utilised in hardening.

Hardening is a heat treatment process that consists of heating, holding and rapid cooling. The steel is heated in order to

change the ferritic-perlitic microstructure to fully austenitic. Holding time should be appropriate for steel thickness to obtain

homogenous temperature. Austenitization temperature for these steels is close to 910 - 930C. Rapid cooling from

austenitization temperature into room temperature is called quenching. The purpose of quenching is to obtain a martensitic

microstructure. Hardened boron steel is a hard, strong and wear-resistant structural material.

In certain applications, hardened steel as such is only an intermediate product. The manufacture of such applications

includes further tempering. Hardening and tempering can also be jointly called quenching+tempering. The purpose of

tempering is to turn the martensitic microstructure into tempered martensite with good toughness properties. Tempering


5


6/8

results in slightly lowered strength and hardness values. The degree of softening depends on the tempering temperature,

which is the most important parameter affecting the mechanical properties of hardened boron steel. The quenched and

tempered boron steel has a favourable combination of strength, hardness and toughness. The hardness-tempering curve is

an essential tool in the metallurgical utilisation of boron steels. A further advantage of tempering results in releasing heat

and structural stresses that appeared during quenching.

As indicated in the figure below, tempering at a temperature of 480 600C clearly improves impact strength and

elongation, whereas tensile strength, yield strength and hardness are lower than those of only quenched boron steel.

Typical hardness-tempering curves for the hardened boron steel B 13S, B 24 and B 27 grades (austenitizationtemperature 920C)

Typical mechanical properties of boron steels when quenched in oil or water

Steelgrade

Heat treatmentcondition

YieldstrengthReN/mm

2

TensilestrengthRmN/mm

2

ElongationA%

HardnessHBW

Impact strengthKVt C KVJ

B 13S Hardened, Oil 750 950 14 300

no tempering Water 900 1200 10 370 -40 50

B 24 Hardened, Oil 850 1250 10 340


B 27 Hardened, Oil 1000 1250 8 380


The values given in the table are averages at room temperature. Austenization temperature used 920 C.

Note: Hardening results presented in the table above and on this web page only give general instructions for the hardening

and other heat treatment of boron steels. Those using hardening and heat treating Ruukki boron steels are specialists in

their own respective fields. Customers can obtain the desired microstructure and mechanical properties for their hardened

steel products by means of product-specific selection of tempering parameters. Expertise in ones own heat treatment

process creates a strong basis for the competitiveness of our customers products.

Forming

The boron steel B 13S and B 24 grades in hot-rolled and hardened condition can be cold formed at room temperature

(+20C) under normal engineering shop conditions up to the thickness of 20 mm. The B 27 grade can be formed in the as-

rolled condition. Boron steel in the hot-rolled condition is more formable than hardened boron steel, because it requires less

bending force. The minimum bending radii for boron steels and recommendations for hot-rolled and hardened steels have

been listed in the table.


6


7/8

Cold formability in the as-rolled condition and as hardened

Thickness (mm)

2.5 -

5

(5) -

6

(6) -

7

(7) -

8

(8) -

10

(10) -

12

(12) -

14

(14) -

16

(16) -

18

(18)

-20

Heat treatment

condition

The smallest allowable inside bending radius (mm)

B

13S

Hot-rolled 10 18 21 24 30 48 - - - -

Oil-hardened 15 18 21 24 30 48 - - - -

Water-hardened 20 24 28 32 40 60 - - - -

B 24 Hot-rolled 15 24 28 32 40 60 70 80 90 100

Oil-hardened 20 30 35 40 50 72 84 96 108 120

Water-hardened 25 36 42 48 60 96 112 128 144 160

B 27 Hot-rolled 20 30 35 40 50 72 84 96 108 120

Oil-hardened - - - - - - - - - -

Water-hardened - - - - - - - - - -

Flanging irrespective of rolling direction. It is recommended to contact Ruukki's Technical Customer Service prior to cold-forming of over 20 mm thick platesand hardened steel grade B 27.

Plates thicker than 20 mm must be preheated the recommended forming temperature is 150200C. Preheating improves

the deformation properties of the plate and guarantees successful bending. Special care must always be taken when

forming thick or hardened plates.

High-quality technology should be used for forming, as wear of tools, insufficient lubrication, surface defects on plates and

burrs in cut edges will impair forming quality. A basic requirement for successful flanging and bending is that, prior to

commencing work, a plate that has been stored in a cold atmosphere is allowed to warm up thoroughly to room temperature

(+20C).

Flame cutting

Special care must be taken in the flame cutting of boron steels particularly so when cutting hardened and/or thick plates.

Prior to commencing work, a plate that has been stored in a cold atmosphere is allowed to warm up thoroughly to room

temperature (+20C). Excessive hardening can be prevented by means of preheating to raise the working temperature. It is

recommended to raise the working temperature when the plate thickness is over 10 mm or when cutting steel grades B 24

or B 27. The table gives the working temperatures recommended for hardened boron steels and boron steels in the hot-

rolled condition. Steel grade B 13S does not require preheating even in the hardened condition, thanks to its low carbonequivalent values and small plate thicknesses.

Recommended working temperatures Boron steels in hot rolled condition or hardened boron steels

Steel grade Thickness mm Working temperature C

B 24 10 30 50 75

B 24 (30) 60 75 125

B 27 10 80 125 175

B 13S does not, even in the hardened condition, require preheating under normal conditions.

When flame cutting hardened boron steels, the hardness of the plates decreases in areas where the temperature exceeds

+200C. Softening is highlighted in the flame cutting of small components. In order to prevent excessive hardening, the

cooling of the cut area must not be accelerated externally on the contrary, the process should be slowed down, if

necessary, by covering the plate with, for example, mineral wool.


7


8/8

Mechanical cutting

In the hot-rolled condition boron steels can be mechanically cut in the same way as structural steels of the same strength

grade, although the wear on cutting blades may be slightly greater. The mechanical cutting of hardened boron steels is

challenging, as the hardness of the steel approaches that of the cutting blades. B 13S and B 24 can be cut using heavy,

robust machines. The mechanical cutting of B 27 is recommended only with reservation, and then only for plates whose

thickness is less than 10 mm. The hardness of the cutting blades must be greater than 53 HRC. Mechanical cutting of small

components must be avoided.

Machining

Boron steels in the hot-rolled condition can be machined in the same way as structural steels of the corresponding strength

grade. Robust machinery and hard metal bits are recommended for the machining of hardened boron steels. Boron steel

plates can be drilled with high-speed steel bits if the bit geometry and cutting fluid are correctly chosen.

Further information on processing in thermal cutting and flame straightening datasheet and in mechanical cutting datasheet.

Occupational safety

Special care must be taken in all stages of handling and workshop processing of boron steels. Safe working methods are

particularly important in bending, flanging and cutting. The handling instructions of the steel supplier and safety instructions

of the workshop must be adhered to in detail. New employees must receive appropriate training before they are allowed to

process boron steels.

Order & delivery

Delivery condition

The delivery condition for hardenable boron steel is hot-rolled.

Inspection document

The inspection document states the chemical composition in compliance with EN 10204.

Ruukki provides boron steel deliveries with the so-called Analysis certificate.

Alternatively, on the customers request, we either provide the Test report 2.2 or the Inspection certificate 3.1., in

accordance with EN 10204.

General delivery information for hot-rolled steels

General delivery information can be found from documents Markings and packing, Ultra-sonic testingand General terms of

sale.

The content of this document has been created from web page last updated 25 Apr 2014

Our sales and technical support are happy to give you more information. Visit www.ruukki.com/contact-us.


8

Hardenable Boron Steel

Documents

Transcript of Hardenable Boron Steel