一种退火态热作模具钢的超细晶化组织热处理工艺，属于热作模具钢热处理技术领域。热处理材料为退火态热作模具毛坯，在模具的心部、表面安装多个检测温度的热电偶；包括第一次高温均匀化、第一次空/水交替淬火、第一次高温回火、回火后二次高温淬火、去应力退火、模具调质处理等步骤。其有益效果是：完全利用热处理工艺调控，可同时细化液析碳化物、马氏体组织及奥氏体晶粒，在保持材料强度的同时提升冲击韧性。晶粒度可由6～7级提升至8～10级，横向冲击韧性可提升15％以上，室温塑性也得到提高。

The invention relates to a heat treatment process of ultra-fine crystalline structure of annealed hot work die steel, which belongs to the technical field of heat treatment of hot work die steel. The heat treatment material is the annealed hot working die blank, and a plurality of thermocouples are installed at the center and surface of the die to detect the temperature; It includes the first high temperature homogenization, the first air/water alternate quenching, the first high temperature tempering, the second high temperature quenching after tempering, stress relief annealing, mold quenching and tempering treatment and other steps. The beneficial effect is that the liquid carbide, martensite and austenite grain can be refined simultaneously by fully utilizing the heat treatment process control, and the impact toughness can be improved while maintaining the material strength. The grain size can be increased from 6 to 7 to 8 to 10, the transverse impact toughness can be increased by more than 15%, and the room temperature plasticity can also be improved.