Carbonitriding

Carbonitriding is a heat treatment process that introduces carbon and nitrogen into a solid ferrous alloy by holding above Ac1 in an atmosphere that contains suitable gases such as hydrocarbons, carbon monoxide and ammonia. The process involves high temperatures, typically around 850°C before the carbonitrided alloy is quench hardened in oil or gas solutions.

This technique is used to increase the surface hardness of a metal, making it more resistant to wear.