The Microstructure and Tensile Properties of Selective Laser Melted Dievar Hot Work Tool Steel

Selective laser melting (SLM) is the dominant additive manufacturing (AM) process of metallic materials to date. The objective of this study was to investigate the effects of heat treatment on the microstructure and tensile properties of SLM Dievar Cr-Mo-V alloyed hot work tool steel. The three-stage heat treatment used in this study was austenitization followed by two tempering processes. The microstructure was analyzed by scanning electron microscopy, X-ray diffractometry, electron backscatter diffraction, and energy dispersive spectrometry. The results showed that the hardness, yield strength (YS), ultimate tensile strength (UTS), and tensile elongation of the as-built steel were 505 HV, 1123 MPa, 1748 MPa, and 11.7 %, respectively. The hardness, YS, UTS, and tensile elongation of the heat-treated steel were respectively 471 HV, 1517 MPa, 1598 MPa, and 13.0 %. The heat treatment obviously increased the YS but decreased the hardness and UTS. The correlations among the heat treatment, microstructure, and tensile properties are discussed in this study.