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Laser powder bed fusion produces geometrically complex metallic components, yet fatigue performance consistently falls below that of wrought counterparts. Surface condition, encompassing as-built roughness, residual stress, porosity, microstructure, and oxide layers, is the dominant factor driving this deficit. This review critically examines surface-driven fatigue mechanisms across Ti-6Al-4V, IN718, AlSi10Mg, and 316L alloys. Post-processing strategies, including mechanical polishing, peening, electrochemical polishing, laser polishing, burnishing, and hybrid approaches, are systematically evaluated. The mechanistic roles of surface roughness as a stress concentrator, near-surface porosity as a crack initiation site, and compressive residual stress as a crack-closure mechanism are discussed. Emerging burnishing techniques, particularly electrical current-assisted burnishing, have demonstrated fatigue life improvements of up to five-fold relative to as-built components. These findings underscore the potential of thermo-mechanical surface modification while emphasizing the need for broader validation across a wider range of alloys and loading conditions. Finally, this review identifies critical research gaps, notably the lack of standardized surface characterization protocols and the limited understanding of fatigue under multiaxial and variable-amplitude loading for surface-treated L-PBF parts, and outlines directions for future work.
Samuel Onimpa Alfred (Sun,) studied this question.