The microstructure and fatigue performance of Inconel 718 produced by laser-based powder bed fusion and post heat treatment

• The fatigue strength increased 27% after heat treatment. • The fatigue crack origins primarily involve the printing defects. • The defect area is pretty larger in fracture surface than in bulk samples. • The fatigue strength could be predicted using the defect size prior to fatigue test . Microstructure, defects and their effects on the fatigue properties of Inconel 718 alloy after laser-based power bed fusion and subsequent heat treatment were extensively investigated. A large number of γ′ and γ″ phases were produced in the heat-treated samples while little changes in grain morphology and texture occurred. The hardness, tensile strength, and fatigue limit increased by 46%, 41%, and 27%, respectively, after heat treatment. The fatigue limit could be predicted using defects based on optical microscopy measurement of the bulk samples and examination of SEM fatigue crack origins via a combination of Murakami model and extreme value statistics.