Additive Manufacturing of 17-4PH Stainless Steel a Review of Properties and Surface Modification

Additive manufacturing (AM) of precipitation-hardened stainless steels, particularly 17-4PH (AISI 630), has gained significant attention due to its ability to produce complex geometries combined with high mechanical performance. However, despite the advantages of Powder Bed Fusion (PBF) technologies such as Selective Laser Melting (SLM) and Direct Metal Laser Sintering (DMLS), components fabricated via AM exhibit inherent surface and microstructural imperfections, including porosity, unmelted particles, and anisotropic microstructures, which may significantly reduce fatigue, wear, and corrosion resistance. This review provides a comprehensive analysis of additive manufacturing techniques applied to 17-4PH steel, focusing on the relationship between processing parameters, microstructure evolution, and resulting mechanical properties. Particular emphasis is placed on post-processing strategies, especially heat treatment and surface modification methods. Among these, shot peening is identified as one of the most effective and economically viable techniques for improving surface integrity. It induces compressive residual stresses, grain refinement, and phase transformation, leading to significant improvements in hardness, wear resistance, corrosion resistance, and fatigue life. Recent studies, including those by Walczak and Świetlicki, demonstrate that shot peening of additively manufactured 17-4PH steel can increase surface hardness by over 100% and significantly reduce wear rates while enhancing corrosion resistance. The synergistic combination of heat treatment and surface engineering is shown to be essential for achieving optimal performance. Overall, this work highlights that while AM enables superior design flexibility, the final performance of 17-4PH components is critically dependent on post-processing, particularly surface modification.