Alloy Steels

An Alloy Steel is a steel with properties due to elements other than carbon like nickel, copper, chromium, and/or aluminum. These additional elements are used to influence the metal's strength, ductility, corrosion resistance, and machinability.

Primary Alloying Element Limits

The content of alloying elements exceeds one or more of the limits:

Manganese > 1.65%
Silicon > 0.60%
Copper > 0.60%

Secondary Alloying Elements

In addition a definite range or a minimum quantity of the following may be required:

Aluminum
Boron
Chromium
Cobalt
Columbium
Molybdenum
Nickel
Titanium
Tungsten
Vanadium
Zirconium

Element	Type	Typical Range (%)	Primary Effect
Manganese	Primary	> 1.65	Increases strength and hardness
Silicon	Primary	> 0.60	Increases strength and elasticity
Copper	Primary	> 0.60	Improves corrosion resistance
Nickel	Secondary	0.5 - 5.0	Increases toughness and ductility
Chromium	Secondary	0.5 - 2.0	Improves hardness and corrosion resistance
Molybdenum	Secondary	0.2 - 1.0	Increases strength at high temperatures
Aluminum	Secondary	0.5 - 1.0	Improves case hardening
Vanadium	Secondary	0.1 - 0.3	Increases strength and wear resistance
Tungsten	Secondary	1.0 - 2.0	Increases hardness and heat resistance
Titanium	Secondary	0.1 - 0.5	Improves strength and creep resistance
Cobalt	Secondary	1.0 - 5.0	Increases high-temperature strength
Boron	Secondary	0.001 - 0.003	Increases hardenability
Columbium	Secondary	0.1 - 1.0	Improves strength and corrosion resistance
Zirconium	Secondary	0.05 - 0.3	Improves strength and fatigue resistance

Element

Type

Typical Range (%)

Primary Effect

Manganese

Primary

> 1.65

Increases strength and hardness

Silicon

Primary

> 0.60

Increases strength and elasticity

Copper

Primary

> 0.60

Improves corrosion resistance

Nickel

Secondary

0.5 - 5.0

Increases toughness and ductility

Chromium

Secondary

0.5 - 2.0

Improves hardness and corrosion resistance

Molybdenum

Secondary

0.2 - 1.0

Increases strength at high temperatures

Aluminum

Secondary

0.5 - 1.0

Improves case hardening

Vanadium

Secondary

0.1 - 0.3

Increases strength and wear resistance

Tungsten

Secondary

1.0 - 2.0

Increases hardness and heat resistance

Titanium

Secondary

0.1 - 0.5

Improves strength and creep resistance

Cobalt

Secondary

1.0 - 5.0

Increases high-temperature strength

Boron

Secondary

0.001 - 0.003

Increases hardenability

Columbium

Secondary

0.1 - 1.0

Improves strength and corrosion resistance

Zirconium

Secondary

0.05 - 0.3

Improves strength and fatigue resistance