Defect–Fatigue Correlations of Post‐processed Laser Powder Bed Fused Metallic Alloys: A Review

Laser powder bed fusion (LPBF) is a versatile and disruptive technology for its capability to manufacture complicated geometries from virtual models and also has other advantages like elimination of complex tooling and material wastage. Despite these unique attributes, the industrial applicability of components made by LPBF is presently limited by process‐induced defects and microstructural anomalies. The reliability of LPBFed components for structural applications necessitates their satisfactory operation in both static and multiaxial loading conditions, implying fatigue performance is the primary requirement. However, the presence of inevitable surface and internal defects impose varied stress concentrations and pose serious constraints for fatigue life of LPBFed alloys. Therefore, application of various post‐processing technologies on LPBFed alloys for enhancing their fatigue life is an active area of research. Herein, state of the art in defect–fatigue correlations of post‐processed LPBFed alloys, specifically, Ti–6Al–4V, SS 316L, AlSi 10 Mg, and Inconel 718, is presented. First, the origin, classification, and quantification of defects are described. Thereafter, the characteristic nonequilibrium microstructures and metallurgical defects of these diverse LPBFed alloys are reviewed and state‐of‐the‐art post‐process treatments in engineering the microstructure and metallurgical defects are presented. Finally, how various post‐process treatments affect fatigue responses of these materials are presented.