Carbonitriding

Steel parts are heated to transformation temperature in a carbon and nitrogen-rich atmosphere to form a hard surface of iron carbides and iron nitrides (after quenching) for resisting sliding wear. Carbonitriding is a surface case hardening process that produces a thin, high hardness case and is a modified form of gas carburizing. This modification consists of introducing ammonia into the carburizing atmosphere to allow for nitrogen from the ammonia to be added to the carburized case as it forms. This thermochemical treatment diffuses both carbon and nitrogen into the surface of the component simultaneously.