Post treatments for improving fatigue performance

Fatigue properties, in general, are highly sensitive to the state of surface, residual stresses, microstructure, porosity, and internal defects in materials. Despite the fast progress in additive manufacturing (AM), many of the abovementioned aspects are still not fully explored and thus there are still multiple knowledge and technological gaps to be addressed before we can fully exploit the high potential of AM for load-bearing applications especially when subjected to cyclic loading. Postprocessing approaches come into play to modulate these properties and compensate for technological shortcomings that lead to irregular surface morphology, internal defects, undesired residual stresses, and anisotropic microstructure. This chapter provides a general overview of the available postprocessing techniques applied to AM metallic materials to enhance their performance under fatigue loading. The posttreatments are categorized based on their intrinsic features and compared in terms of limitations, efficiency, and future prospects.