Effects of Two Tempering Treatments at Different Temperatures on Microstructure and Room/High-Temperature Wear Resistance of H13 Steel

As a typical Cr-Mo-V series hot work die steel, H13 steel is widely used in hot extrusion dies under harsh service conditions. Tempering is a vital post-quenching process for regulating microstructural evolution and comprehensive mechanical properties. Since relevant systematic comparative studies remain insufficient, industrial-grade H13 steel was adopted in this work. Specimens were quenched at 1000 °C, followed by single tempering at 520 °C and double tempering at 580 °C. Their microstructure, microhardness, and wear resistance at 25 °C and 580 °C were characterized, and the underlying mechanisms were analyzed. The results show that single tempering at 520 °C produces tempered martensite and finely dispersed carbides with secondary hardening behavior. Its microhardness reaches 590.83 HV, resulting in the best wear resistance at both room and high temperatures. Double tempering at 580 °C causes carbide coarsening, and the microhardness slightly declines to 580.60 HV. Although toughness is enhanced and residual stress is fully released, wear resistance deteriorates. This study optimizes the tempering parameters for H13 steel, provides technical support for die production, and offers theoretical guidance for the technical upgrading of the hot work die steel industry.