Assessment of microstructural evolution and fatigue behavior in cold-rolled and DMLS Inconel 718 samples

This study offers a comparative assessment of Direct Metal Laser Sintered (DMLS) Inconel 718 post-processed by cold rolling and heat treatment and shows that post-processing tends to have the most significant effect on mechanical properties. These combined results indicate that thermal conditioning results in a more stable microstructure characterized by strengthening precipitates and thereby increased resistance to cyclic loading. Rich ductility-based features in cold-rolled specimens change to a mixed mode of fracture in heat-treated samples, depending on the relative synergism of microstructural refinement and the mechanisms of deformation as illustrated by fractographic observations. The differences in surface characteristics between the two processing paths, these can be overshadowed by heat treatment-induced microstructural hardening. Here, the outcomes presented a significant step in studying the influence of thermal post-processing on the fatigue life of additively manufactured structural alloys with a focus on Inconel 718 for high-temperature and high-stress engineering applications in a cost-effective manner.