Hardness of steel greatly improves with Cyaniding.

Cyaniding is a heat treatment process that involves the addition of carbon and nitrogen to the surface of steel. It is typically used to improve the surface hardness and wear resistance of steel components. During the cyaniding process, the steel is heated in a furnace at a temperature between 850°C and 950°C in the presence of a cyanide salt.

How Cyaniding improves the hardness of steel:

1. Introduction of Carbon and Nitrogen: Cyaniding introduces carbon and nitrogen into the surface layer of the steel. These elements form hard compounds such as iron carbides and iron nitrides, which significantly increase the hardness of the steel.

2. Case Hardening: Cyaniding is a type of case hardening process. Case hardening refers to the hardening of the outer layer (case) of the steel while maintaining a softer and more ductile core. This allows the steel to have a tough core with increased hardness on the surface, providing a combination of wear resistance and toughness.

3. Formation of Compound Layers: During cyaniding, the carbon and nitrogen atoms diffuse into the surface layer of the steel, forming compound layers. These compound layers are harder than the base steel and can significantly increase the surface hardness.

4. Increased Carbon Content: The addition of carbon during cyaniding increases the carbon content of the steel in the surface layer. This higher carbon content promotes the formation of hard carbides, which contribute to the improved hardness.

5. Quenching: After the cyaniding process, the steel is typically quenched in oil or water to rapidly cool it. This quenching step helps to transform the formed compounds into a hardened microstructure, further enhancing the hardness of the steel.

6. Surface Resistance: The increased hardness obtained through cyaniding improves the surface resistance of the steel, making it more resistant to wear, abrasion, and surface deformation.

Overall, cyaniding is an effective heat treatment process for improving the hardness of steel. It introduces carbon and nitrogen into the surface layer, forms hard compounds, and enhances the wear resistance and surface hardness of the steel.