The quenching and tempering of metal parts with oil, the oil quenching and tempering, is assigned to the thermal heat treatment processes. It is a combined process of heating to the so-called austenitizing temperature with subsequent quenching in special hardening oil and reheating, the tempering.
1. austenitisation: Here the normally ferritic – pearlitic structure is transformed into the austenitic structure.
2. quenching: The material falls into an oil bath and cools rapidly, forming a martensitic structure. That is very hard and brittle.
3. tempering: The necessary toughness is achieved by reheating.