Tailoring microstructure, mechanical properties, and wear of LPBF-fabricated H13 tool steel through post-heat treatment

Laser Powder Bed Fusion (L-PBF) has emerged as a transformative additive manufacturing technique, offering the capability to fabricate complex geometries and customized components directly from digital models. Its application in producing H13 tool steel dies for hot work tooling presents a promising alternative to conventional manufacturing. This study investigates the influence of laser scanning speed (ranging from 150 to 600 mm/s) and subsequent multi-stage heat treatments including annealing, quenching, tempering, and double tempering on the microstructure and mechanical performance of L-PBF-processed H13 steel. The results indicate that increasing scan speed leads to higher martensite content but adversely affects tensile strength and hardness. In contrast, the annealing stage refined the microstructure, enhancing ductility and promoting phase homogenization. While quenching followed by tempering improved toughness and wear resistance, it was accompanied by a reduction in tensile strength. Notably, a 1200% increase in impact toughness was observed after tempering at the lowest scan speed, despite a slight decrease in wear resistance. The microstructural evolution, porosity levels, and phase transformations are comprehensively analyzed to explain the observed trends, guiding the optimization of L-PBF and heat treatment parameters for tooling applications.