Abstract: Deep cryogenic treatment process parameters of 18Cr2Ni2MoNbA carburized steel were selected and optimized by using orthogonal test. The effect of cryogenic time, low temperature tempering temperature and low temperature tempering time on the wear resistance of the steel was studied, and the wear scar morphology, microstructure, retained austenite and microhardness were analyzed. The results show that when cryogenic treated at -196 ℃ after carburizing and quenching, the influence of cryogenic parameters on the wear amount of the 18Cr2Ni2MoNbA steel is in the following order of significance as cryogenic time, low temperature tempering time and low temperature tempering temperature. The cryogenic treatment can effectively increase the wear resistance of the steel, and the wear amount of the steel under the cryogenic parameters as cryogenic time of 1 h, low temperature tempering temperature of 120 ℃ and low temperature tempering time of 2 h is the smallest, which is reduced by 46.67% compared with the steel without cryogenic treatment, and the wear mechanism changes to abrasive wear and oxidation wear. The carbides in the carburized layer precipitate along the grain boundaries after cryogenic treatment, while small particles of carbides are diffused on the matrix. The cryogenic treatment can reduce the retained austenite content of the steel and increase the martensite content, which increase the microhardness of the surface carburized layer, and improve the wear resistance of the 18Cr2Ni2MoNbA steel.

Key words: 18Cr2Ni2MoNbA steel, cryogenic treatment, orthogonal experiments, wear resistance