Machining and heat treatment as post-processing strategies for Ni-superalloys structures fabricated using direct energy deposition

The aim of this study is to determine the most suitable post-processing routines to enhance the surface integrity of components produced with Inconel 718 superalloy by additive manufacturing. The components were fabricated by Direct Energy Deposition (DED) followed by two typical post-processing methods: machining and heat treatment. The effect of the post-processing sequence (machining + heat treatment or heat treatment + machining) and the corresponding effects on the surface integrity of these components were investigated in terms of surface finishing, microstructure, micro-hardness and residual stresses. Finally, suitable solutions in terms of additive manufacturing - post-process operations have been reported.