Optimization of vacuum isothermal quenching process and microstructure analysis of die steel Cr12MoV

Abstract This study first employed a vacuum isothermal gas quenching process to heat‐treat Cr12MoV in an attempt to achieve a mixed structure of martensite and lower bainite. Based on an analysis of the impact of different isothermal gas quenching process parameters on the properties and microstructure of Cr12MoV steel, with a focus on material impact toughness and Rockwell hardness, the particle swarm optimization method was used to optimize the vacuum gas quenching process parameters for Cr12MoV steel. Using the optimized process parameters, Cr12MoV steel was subjected to vacuum isothermal gas quenching treatment. Microstructure observations and phase analysis revealed that the post‐quenching structure consisted of an excellent combination of martensite and lower bainite dual‐phase structures, with reduced carbide content and even distribution. After two tempering processes, it was observed that the residual austenite content significantly decreased. The vacuum isothermal gas quenching‐tempering process effectively reduced material anisotropy and tool deformation.