The treatment under 0oC it is imposed to the pieces in which the residual austenite is not wished by the negative effect on the physico – mechanical properties and on the dimensional stability. The classic treatment can not assure the rotation precision on the bear steels, giving a quantity of 10 – 18 % residual austenite. In this paper the influence of cryogenic quenching temperature on the kinetics of austenite – martensite transformation.
