A case-hardening process carried out around 500 to 550 C in ammonia gas or plasma, well below the steel's transformation temperature, so there is no quench and very little distortion. Gears can be finish-machined or ground before nitriding. The case is hard but shallow, typically a few tenths of a millimeter, so nitriding suits large thin gears and moderately loaded teeth, while the heaviest loads go to carburized gears.
Ring gear is too big and thin to carburize without potato-chipping it, so we're nitriding it after finish grind.
Also heard as
- gas nitriding
- plasma nitriding
- ion nitriding
Related terms
Carburizing
A heat treatment that diffuses carbon into the surface of low-carbon steel gears, then quenches for a hard case.
Case depth
How deep the hardened surface layer of a gear tooth goes, usually measured to a set hardness such as 50 HRC.
Induction hardening
Hardening gear teeth by heating them locally with an induction coil and quenching immediately.