Numerical simulation of microstructure and hardness distributions during dual-medium quenching of high-temperature carburized 18Cr2Ni4WA steel

This study focuses on the cylindrical samples of 18Cr2Ni4W alloy steel, employing finite element analysis to investigate the evolution of microstructure and properties under different quenching media. It is indicated that the simulation results are in good agreement with experimental data. After carburizing and quenching, the final microstructure consists of martensite, retained austenite, and carbides, with hardness decreasing gradually from the surface to the core. Compared to single-medium quenching, dual-medium quenching increases the bainite content in the core from 20.5% to 45.7% and decreases the martensite content in the core from 79.4% to 54.3% through adjustment of cooling rates. The increase of bainite content and the reduction of martensite content effectively increase the toughness of the transition layer and core regions. This study not only elucidates the influence of quenching conditions on the carbon concentration, microstructure, and hardness of 18Cr2Ni4W alloy steel, but also provides scientific guidance for the control of microstructure and properties during carburizing heat treatment.