Enhancing Fatigue Strength of Selective Laser Melting‐Fabricated Inconel 718 by Tailoring Heat Treatment Route

Voids are always unavoidably introduced into metals fabricated by selective laser melting (SLM), and thus greatly degrade fatigue performance of metals. Such a fatal weakness strongly limits the application of SLM‐fabricated metals to load‐bearing structural components for the long‐term service. Here, the authors found that fatigue strength of SLM‐fabricated Inconel 718 is significantly improved after the proper heat treatment route not only due to the elimination of Laves phases and the precipitation of γ″/γ′ strengthening phases, but also the appearance of ultrafine‐scale acicular δ phases, which effectively suppressed the degraded effect of voids. The finding may provide a potential strategy to enhance fatigue strength of SLM‐fabricated materials by tailoring heat‐treatment route.