Austempering
Heat treatment process for steels involving austenitizing followed by isothermal quenching in a salt bath to produce a bainitic microstructure with high toughness.
Austempering means, in essence: you heat the part to austenitizing temperature and then place it in a salt bath that is tempered to the bainite stage. It stays there until the structure is completely transformed. The bath must be clean and dry, otherwise it will not cool evenly. The result is a tough, strong bainitic structure that is significantly less sensitive to cracking than martensitic structure. If you miss the temperature in the bath or pull it out too early, you get mixed structures – the part becomes brittle or soft, depending on where you miss. After transformation, you can continue processing the part normally; grinding or straightening is no problem. Just make sure you don't shorten the holding time in the bath, otherwise the transformation is not complete.