Cryogenic treatment process for reducing content of retained austenite in steel and iron material

The invention belongs to the technical field of material treatment processes, and particularly relates to a subzero treatment process for reducing the content of retained austenite of a steel material. The method comprises the following steps: providing a quenched steel and iron material; cooling the quenched steel and iron material to-170 DEG C to-196 DEG C, and carrying out heat preservation for the first time; heating the steel and iron material subjected to the first heat preservation to-70 to-90 DEG C, and carrying out second heat preservation; and heating the steel and iron material subjected to secondary heat preservation to room temperature. According to the subzero treatment process, the transformation characteristics of the continuous transformation stage and the isothermal transformation stage are considered, the treatment time and the treatment cost can be reduced, meanwhile, the content of retained austenite of the quenched steel and iron material is effectively reduced, and the effects of improv