Selective laser melting of Inconel 718: Effect of thermal treatment on mechanical properties

The work presents a comparative study on the hardness and compressive strength of selective laser melted Inconel 718 samples in both as-prepared and heat-treated conditions. Three different heat treatment procedures were carried out i.e., aging, homogenization, and standard heat treatment. Results indicate that the maximum micro-hardness (549 HV0.2) was observed for the sample in the as-prepared condition, and it decreases subsequently after heat treatment (irrespective of the heat treatment conditions). On the other hand, the compressive strength of the sample after standard heat treatment shows the maximum strength as compared to its other counterparts. The contradiction between the hardness and compressive properties may be explained due to the presence of precipitated in the nanoscale, which may not be picked up during the hardness testing, but have its influence during bulk deformation. Moreover, the XRD analysis shows only the peaks of the fcc phase corresponding to the Ni3(AlTi) phase – γ – phase in the as-prepared condition.