On the link between as-built surface quality and fatigue behavior of additively manufactured Inconel 718

Inconel 718 is widely used in challenging structural applications because of its excellent high temperature mechanical properties. Selective Laser Melting (SLM) of Inconel 718 powder is increasingly used to fabricate customized parts for jet engines. The surface quality of SLM parts is influenced by powder characteristics, process parameters and the layer-wise fabrication. The as-built fatigue behavior is negatively affected by the inferior surface quality of SLM parts compared to machined version. Here the fatigue behavior of SLM Inconel 718 is investigated using specimens fabricated with two different SLM systems and different directions of applied stress with respect to build direction. Fatigue test results are interpreted in the light of metallographic and fractographic investigations.