Effect of deep cryogenic treatment on the properties of AISI M2 steel

Deep cryogenic treatment is a special kind of bulk hardening heat treatment performed on a big variety of tool and carburized steels, to improve mechanical properties and wear resistance. The mai reason for this is the complete transformation from austenite into martensite plus the formation of submicrometric carbides dispersed in the tempered martensitic structure. The greatest improvement in properties is obtained by carrying out the deep cryogenic treatment between quenching and tempering. However, a significant improvement can be obtained even by treating the tools at the end of the usual heat treatment cycle, i.e. the finished tools. This last solution is more flexible than the other one and can extend the use of the treatment to many practical applications. In order to check the potential of deep cryogenic treatment on the performance of the finished products, an investigation was carried out on the AISI M2 high speed steel quenched, tempered and deep cryogenically treated. The findings shows that the cryogenic treatment promotes the precipitation of submicrometric carbides, that increment wear resistance and nano-hardness and decrease residual stresses.