Case Hardening Process: Cyaniding

Cyaniding is a case hardening process used to increase the surface hardness of low carbon steel. In this process, the steel is heated in the presence of a cyanide salt, which diffuses carbon and nitrogen into the surface of the steel. This creates a hard, wear-resistant outer layer while maintaining a tough and ductile core.

Steps Involved:

1. Preparing the Steel: The low carbon steel is cleaned and degreased to remove any surface contaminants.

2. Heating the Steel: The steel is heated in a furnace to a temperature between 760°C and 870°C.

3. Introducing the Cyanide Salt: The cyanide salt is added to the furnace, and the steel is held at the desired temperature for a specific period. The cyanide salt decomposes, releasing carbon and nitrogen, which diffuse into the surface of the steel.

4. Quenching: The steel is removed from the furnace and immediately quenched in a bath of oil, water, or brine. This rapidly cools the steel, creating a hard outer layer.

Advantages of Cyaniding:

1. Cyaniding produces a hard, wear-resistant surface while maintaining a tough and ductile core.

2. It can be used on low carbon steels, which are typically more affordable than high carbon steels.

3. The process is relatively fast and cost-effective.

4. Cyaniding can be used to produce a range of surface hardness levels, depending on the specific needs of the application.

Conclusion:

Cyaniding is a case hardening process that can be used to increase the surface hardness of low carbon steel. It involves heating the steel in the presence of a cyanide salt, which diffuses carbon and nitrogen into the surface of the steel. This creates a hard, wear-resistant outer layer while maintaining a tough and ductile core. Cyaniding is a fast and cost-effective process that can be used to produce a range of surface hardness levels.