Influence of Post Deposition Heat Treatments on Tensile Strain Rate Effects for Selective Laser Melting (SLM) Inconel 718

In this study, the influence of post-deposition heat treatments on the morphology and dynamic tensile performance of a Selective Laser Melting (SLM) Inconel 718 (IN718) was investigated for the first time. Examinations of the microstructural evolution revealed an orientation-dependent columnar melt-pool-dominated morphology with powder-induced voids in the as-built state. SLM IN718 samples subjected to a complete standardized thermal post-deposition heat treatment method, including stress relief, hot isostatic pressing, and solution treatment and aging, resulted in a decrease in porosity and a more equiaxed grain shape. Quasi-static and high-rate tensile experiments were used to examine the strain rate dependence on tensile behavior along the build direction in the SLM deposited material. Similar to wrought polycrystalline metallic material, the SLM IN718 tensile strength increased at the expense of ductility as porosity decreased and nucleated strengthening precipitates.