Influence of Surface Mechanical Attrition Treatment (SMAT) post-treatment on microstructural, mechanical and tensile behaviour of additive manufactured AISI 316L

Additive Manufacturing (AM) is a technology in constant growth, thanks to its numerous advantages compared to conventional manufacturing. In this paper, Surface Mechanical Attrition Treatment (SMAT) was performed on 316L stainless steel parts produced by the Laser Powder Bed Fusion (LPBF) technique, also commonly known as Selective Laser Melting (SLM). Experimental characterizations (cross-sectional optical micrographs, X-ray diffraction, phase analyses, surface roughness, micro-tensile testing and microhardness profiles) show that SMA treatment can reduce the surface roughness by a factor of 10 and can increase the microhardness in the layer beneath the treated surface up to 45%. SMAT can also transform the initial near-surface tensile residual stresses present in AM parts into compressive ones and enhances the mechanical properties of SLM parts. This work demonstrates the potential of SMAT as a post-treatment to improve surface quality and increase yield strength while retaining good ductility of SLM manufactured parts.