Abstract: | The heat treatment under 0?C (273 K) is a continuation of the quenching at negative temperatures, especially at those inferior to that of the Ms point. The aim of this treatment is the complete transformation of residual austenite in martensite. It is applied to steels with carbon content greater than 0,6%C, at which the Ms point is situated between -3?C (200K) and -93?C (180K) and to alloy steels, at which the Ms point is situated between -100?C (173K) and -140?C (133K). In the paper is described an installation for realizing the cryogenic treatments, which use an frigorific agent prepared outside-liquid nitrogen. |
