Alloying Elements And Their Properties

Effect of alloying element on steel image

Specific alloy elements and quantities determine the type of steel alloy and their particular properties.

The main effects of some of the most common elements are:

ALUMINUM
Used in small amounts; it acts as a deoxidizer for molten steel.
Produces a fine Grain Steel (by limiting the growth of austenite grains).
Promotes nitriding.
BORON
Increases the hardenability.
CHROMIUM
Increase hardness.
Improves wear, abrasion, corrosion resistance.
COBALT
Increase tempering resistance at high temperatures.
Cobalt is often used in high-speed steels.
COPPER
A significant increase in corrosion resistance.
Improve formability & machinability.
Counteracts brittleness due to sulphur.
LEAD
Lead is not combined with steel; it is in the form of tiny inclusion.
Significantly improve machinability.
MANGANESE
The primary element in all commercial steels. It acts as a deoxidizer and also neutralizes the harmful effects of sulphur.
Improve hardenability, strength at high temperature.
Increase carbon penetration during carburization.
Reduce weldability and ductility.
MOLYBDENUM
Increases the toughness and strength at high temperatures.
Protection from corrosion caused by chloride and sulphur.
Used in HSS cutting tool, high-pressure cylinders, turbine rotor.
NICKEL
Promote an austenitic microstructure.
When used in conjunction with chromium, it increases the hardness and toughness.
Resistance to corrosion and oxidization.
NITROGEN
Add in some steel to promote the formation of austenite.
Improves yield strength.
PHOSPHORUS
At higher rates, phosphorus reduces ductility, thereby increasing the tendency of the steel to crack when working in the cold.
Improves machinability in free-cutting steels.
Used in spring steels.
SILICON
Promotes a ferritic microstructure.
Larger grain sizes
Leading to greater magnetic permeability.
Improves strength, elasticity.
Increase hardenability.
It is used as a deoxidizer.
SULPHUR
Usually an impurity and maintained at a low level. However, sometimes intentionally added in large amounts (from 0.06 to 0.30%) to increase the machinability of alloy steels.
TITANIUM
It is used to inhibit grain growth.
High temperature strength.
Increase resistance to oxidization.
TUNGSTEN
Increase pitting corrosion resistance.
To improve heat resistance.
It is used in alloy tool steels.
VANADIUM
Helps in the formation of fine grain size.
It increases strength and also the fatigue strength.
Increases tempering resistance.

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