Effect of post-fabrication treatments on surface residual stresses of additive manufactured stainless steel 316L

Abstract

In this work, an investigation was made to analyze the surface residual stresses on additive manufactured stainless steel AISI 316L in as-built and post-treated conditions. Direct metal laser sintering was used to fabricate the metal blocks. X-ray residual stress analysis on the as-fabricated surface revealed the presence of an inhomogeneous and irregular distribution of residual stresses in the as-built condition ranging from - 30 MPa to 111 MPa. It was mainly due to the localized laser heat source that caused variations in stresses at a lattice level. Heat treatment was performed for providing relief to the residual stress from the as-built condition showed significant relief of residual stress, which was lesser than 50% compared to as-built condition. Beneficial compressive residual stress induced by shot peening and lapping resulted in high magnitude compressive stresses on the surface. Also, homogeneous distribution of residual stress was found on the peened and lapped surface layer with an average of - 531 MPa and - 554 MPa, respectively.