Effects of Common Alloying Elements in Steel

By definition, steel is a combination of iron and carbon. Steel is alloyed with various elements to improve physical properties and to produce special properties such as resistance to corrosion or heat. Specific effects of the addition of such elements are outlined below:

Phosphorus – increases strength and hardness and decreases ductility and notch impact toughness of steel.

Manganese – strength and hardness; decreases ductility and weldability; effects hardenability of steel.

Sulfur decreases ductility and notch impact toughness Weldability decreases. Found in the form of sulfide inclusions.

Silicon – one of the principal deoxidizers used in steel making. In low-carbon steels, silicon is generally detrimental to surface quality.

Copper – detrimental to hot-working steels; beneficial to corrosion resistance (Cu>0.20%)

Nickel – ferrite strengthener; increases the hardenability and impact strength of steels.

Molybdenum increases the hardenability; enhances the creep resistance of low-alloy steels

Carbon (C)– The most important constituent of steel. It raises tensile strength, hardness, and resistance to wear and abrasion. It lowers ductility, toughness and machinability.

Tantalum (TA)– Used as stabilizing elements in stainless steels. Each has a high affinity for carbon and forms carbides, which are uniformly dispersed throughout the steel. Thus, localized precipitation of carbides at grain boundaries is prevented.

Titanium (TI)- Used as stabilizing elements in stainless steels. Each has a high affinity for carbon and forms carbides, which are uniformly dispersed throughout the steel. Thus, localized precipitation of carbides at grain boundaries is prevented.

Tungsten (W)- Increases strength, wear resistance, hardness and toughness. Tungsten steels have superior hot-working and greater cutting efficiency at elevated temperatures.

Vanadium (V)- Increases strength, hardness, wear resistance and resistance to shock impact. It retards grain growth, permitting higher quenching temperatures. It also enhances the red-hardness properties of high-speed metal cutting tools.