Alloying Elements of Steel | Alloying Elements Properties and Effects

Alloying Elements of Steel | Alloying Elements Properties and Effects

A steel composition is made up of different elements combined to form the final product. In metalwork, these elements are called alloying additions.

Each alloy addition element affects steel properties differently. Depending on the desired properties, the proportion of alloying additions is added.  

Alloying Elements of Steel

The following are alloying elements and properties.

  1. Carbon
  2. Silicon
  3. Manganese
  4. Phosphorus
  5. Sulfur 
  6. Chromium 
  7. Molybdenum
  8. Nickel 
  9. Copper
  10. Boron
  11. Nitrogen
  12. Tungsten
  13. Cobalt.


Carbon is the most important element for strength and hardness. As the level of carbon is increased, the tensile strength and hardness also increase.

Carbon is a cheap way of increasing strength, and it is essential for the formation of microstructures.


Phosphorus is usually classed as an impurity as it significantly reduces the toughness and ductility of steel, but it can be used as a solid solution strengthener.


Sulfur is usually classed as an impurity as it reduces the steel’s ductility, toughness, and weldability. Sulfur conforms with iron to produce a low melting point impurity called iron sulfide.

This can collect along grain boundaries and caused the steel to break up during hot working. This is called hot shortness. Sulfur is sometimes added to steal to aid machineability.


 Manganese has a significant effect on hardenability and can be found in most commercial steels. Manganese constrains thin the steel through solid solution strengthening. It also combines with sulfur to prevent hot shortness.


Chromium increases the hardenability of steel. It conjoined together with the carbon to form very stable carbides, which is excellent for wear and abrasion resistance. It is used in high levels of stainless steel for corrosion resistance.

It does this by creating a protective oxide film on the surface of the stainless steel.


Molybdenum also increases the hardenability of steels. When combined with chromium and Nickel, it has a strong multiplicity of effects on hardenability. It is both in alloy and stainless steel.


As with chromium and molybdenum, Nickel increases steel’s hardenability and can increase steel’s toughness, particularly at low temperatures.

Again, it is present in large amounts in stainless steel.


Silicon is mainly used to remove oxygen from steel in a process called deoxidation. The removal of oxygen in steel is important as oxygen conform voids in steel, know as blowholes and porosity oxygen, can also be combined with other elements to form brittle particles known as oxides.

Silicon could be used to increase the fluidity when casting steels.


Aluminum is primarily used to deoxidize the steel. It can combine with nitrogen to form nitrites, which can restrict grain growth.


  Also called Colombian in small amounts, it can increase yield strength, tensile strength, and toughness.


Vanadium is used to increase the hardened ability and toughness of steel through its ability to restrict grain growth.


Boron can significantly increase the hardenability of steals on, can enhance the effect of other alloying elements.


Nitrogen is often added in combination with other elements to form nitrites. These nitrites increase the hardness and tensile strength, but at the expense of toughness and ductility.

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