Carbonitriding is one of the thermochemical processes. During this process the surface of workpieces is enriched with carbon and Nitrogen to improve the mechanical properties. Carbonitriding, similar to Carburizing, typically consists of three steps.

1.- In the first step workpieces are exposed to a carbon and nitrogen emitting environment. This increases the carbon and nitrogen percentage. The carbon/nitrogen profile and the penetration depth depend on the time at temperature, the amount of supplied carbon and nitrogen, the temperature and the kind of steel used.

2.- In the second phase, quenching (hardening) takes place. This can be performed directly from the carburizing temperature, or after an interstage cooling or new heating to a new material-specific curing temperature.

3.- The third step is tempering and mainly serves to diminish the highest stresses in the structure and to diminish the grinding crack sensitivity.