Austempering

Austempering means: after hardening, you hold the steel in a hot bath at a constant temperature until a bainitic structure forms. This gives the material a good combination of strength and toughness without having to temper it afterwards. If you don't hit the temperature or holding time precisely, you won't get a uniform structure and the parts will be either too hard or too soft. So you have to control the bath temperature exactly and choose the time so that the transformation runs to completion.