Influence of heat treatment process on microstructure and properties of 23CrNi3Mo steel

In order to improve the quality of drill, different heat treatment processes of a 23CrNi3Mo drill steel were conducted, and the influence of heat treatment parameters on microstructure and mechanical properties of the 23CrNi3Mo drill steel was studied by means of SEM, TEM, tensile test and impact test using orthogonal experiments. The heat treatment process was optimized based on the investigation. The results show that the optimum heat treatment process is quenching at 920°C for 45 min in oil and tempering at 200°C for 120 min and then cooling in air for the 23CrNi3Mo drill steel. The carbide may have an adverse impact on impact toughness. In the process of heat treatment, the precipitation of carbide should be avoided. So the holding time of 45 min and longer for quenching is recommended with the tempering temperature at or lower than 200°C.