Quenching and Tempering of Steel

a heat treatment that consists in hardening and subsequent high-temperture tempering at 550°–650°C.

The quenching and tempering process results in the formation of the homogeneous and disperse sorbite structure, which affords a good combination of strength, ductility, impact strength, and critical temperature for the transition from the ductile state to the brittle state. The most pronounced effect is observed when ferrite and bainite, the nonmartensitic products of austenitic transformations, do not form during hardening. To prevent the development of temper brittleness, cooling in oil or water is necessary in many cases after high-temperature tempering. The use of a specific refining cycle is dictated by the properties and composition of the steel desired.

The quenching and tempering process is sometimes used as an intermediate treatment to create a homogeneous initial structure before hardening.