ALLOY STEELProperties and uses

What is alloy steel ?

Alloy steel is steel that is alloyed with a variety of elements in total amounts between 1.0% and 50% by weight to improve its mechanical properties.

The definition of alloy steel does not include those effects which are negative or cure of ills that the steel might possess were the alloying elements not added

The term alloy steel is the standard term referring to steels with the other alloying elements in addition to the carbon .

Common alloyants include Mn,Cr,Mo,V,Si and B. less common alloyants include Al, Co,Cu,Ti,W,Sn,Zn,Pb,Zr.

PROPERTIES

Alloy steel has some of its properties better than carbon steel. tensile STRENGTH Hardness Toughness Wear resistance Creep High temperature resistance To achieve some of these improved properties the metal may require heat treating

SIGNIFICANCE

Alloying elements are added to achieve certain properties in the material Added in lower percentages (less than 5%) to increase strength or hardenability Added in larger percentages (over 5%) to achieve special properties such as corrosion

resistance or extreme temperature stability. Mn,Si,Al are added during the steel making process to remove dissolved oxygen ,

sulphur,and phosphorus from the melt. Mn,Si,Ni and Cu are added to increase strength by forming solid solutions in ferrite.

USES

AREAS USESAutomotive Transmission Parts, Engine Components, Steering Components, High

Tensile Fasteners, Fuel Injection Pumps, Bearing Axles, Gears, Crankshaft, Transmission Chains, Springs, Combustion chamber, Axles, Wheel Hubs

Engineering  Cutting Tools, Structural Steel)Industry Mining Machinery, Energy exploration machinery, food-processing

units(non-corrosive environmentconstruction Reinforcing barsagriculture Tractor partsHome Utensils, decorative purposesrailways Wagon Axles, Crankshafts, Cushioning Device Components, Steel Liners,

Traction Gears

USES

They may find uses in • Aircraft industry • Chemical processing • Food processing • Household items • Dairy industry

ADVANTAGES AND DIADVANATGES

Advantages Disadvantages

• Greater hardenability.• Less distortion and cracking • Greater stress relief at given hardness• Less grain growth• Higher elastic ration and endurance

strength• Greater high temperature strength • Batter machinability at high hardness• Greater ductility at high strength.

• Cost • Special handling • Tendency toward austenite retention• Temper brittleness in certain grades.

PURPOSE OF ALLOYING

Strengthening of the ferrite. Improved corrosion resistance. Better hardenability Grain size control Greater strength Improved machine ability Improved high or low temperature stability Improved ductility Improved toughness Better wear resistance.