Investigation of Residual Stress and Elastic Anisotropy in 17-4 PH Stainless Steel Manufactured via Atomic Diffusion Additive Manufacturing and Treated with Surface Mechanical Attrition

The study explores the evolution of residual stress and elastic anisotropy in 17-4 PH stainless steel produced through Atomic Diffusion Additive Manufacturing (ADAM) and treated with Surface Mechanical Attrition Treatment (SMAT). Employing angle- and energy-dispersive X-ray diffraction techniques, the research analyzes residual stress profiles in both as-built and SMAT-treated samples. The results reveal that while the as-built samples exhibit tensile stresses near the surface, which decrease with depth, the SMAT-treated samples demonstrate significant compressive residual stresses ranging from -200 MPa at the surface to -600 MPa in deeper regions. Microstructural analysis using electron backscattered diffraction (EBSD) indicates the formation of a refined subgrain structure after SMAT, with the fine subgrain fraction increasing notably in the subsurface layer. This surface modification is crucial for enhancing the fatigue resistance of additively manufactured components, as fatigue failures often initiate in the surface layers. The research underscores the importance of selecting an appropriate grain interaction model for accurately calculating X-ray Stress Factors, which is essential for reliable residual stress characterization. Overall, the findings contribute to improved understanding and optimization of mechanical properties in additive manufacturing processes, promoting the usage of SMAT as a viable post-processing method for achieving desired material characteristics.

National Science Centre (NCN), No. UMO-2023/49/B/ST11/00774.