Effects of Heat Treatment Processes on the Microstructure and Properties of 20CrMo Alloy Steel

A correlation study and analysis were carried out on the microstructure, mechanical properties, and hardness of 20CrMo alloy steel with different secondary quenching processes. The results indicate that, when subjected to secondary quenching in the temperature range of 775–850 ℃, as the quenching temperature increases, the tensile strength of 20CrMo increases while its ductility decreases. The increment in hardness is higher when quenched at 800–825 ℃ compared to other temperature ranges, primarily due to variations in the post-quenching phase structure and proportions. At a secondary quenching temperature of 775 ℃ and tempering at 150–200 ℃, the material exhibits a good balance between strength and ductility. It achieves a tensile strength of 1050 MPa and an elongation of over 15%, with a reduction in area exceeding 45%. Within the 150–200 ℃ low-temperature tempering temperature range, the influence of tempering temperature on the mechanical properties of 20CrMo alloy steel is limited.