Enhancing Mechanical Properties of Additively Manufactured H13: A Two-Step Approach Integrating Processing Parameters Optimization and a Tailored Heat Treatment

Abstract

Rapid solidification during Additive Manufacturing (AM) of H13 steel leads to mesoscopic segregation of alloying elements, which are prone to oxidation during post-AM heat treatment. The presence of oxide particles significantly reduces the tensile strength of powder bed fusion-ed (PBF-ed) H13 steel. The size and distribution of the oxides depend on the selection of both PBF and heat treatment parameters. The purpose of this paper is to maximize the tensile strength of PBF-ed H13, making it comparable to conventional forged and heat treated H13.The research was conducted in two steps. First, PBF processing parameters of laser power, laser speed, hatching space, printing strategy, and preheating temperature were optimized to minimize manufacturing defects and maximize mechanical strength. In the second step, tailored heat treatments were investigated, including annealing at 500 °C for 2 h, quenching at 1020 °C for 1 h, and double tempering at 550 °C for 2 h. Experimental results show that annealing at 500 °C effectively reduces residual stress but does not achieve sufficient elongation. The combination of quenching and tempering significantly enhances elongation to 15% while maintaining a tensile strength of approximately 1517 MPa. This optimized heat treatment strategy also minimized the size and distribution of oxide particles, keeping them under 6 μm in diameter, thereby reducing their detrimental impact on mechanical properties.

Graphical Abstract