Stress corrosion cracking behavior of austenitic stainless steel 316L produced using laser-based powder bed fusion

Abstract

Austenitic stainless steel UNS S31603 (SS316L) is widely used in the resources industry due to its excellent corrosion resistance, ductility, and weldability. Recently, laser-based powder bed fusion (LPBF) manufacturing has gained popularity for creating SS316L components with complex geometries and superior mechanical properties. However, the rapid melting and solidification of the deposited layers during the thermal cycle of LPBF produce residual stresses. Components manufactured through LPBF are frequently used under applied stress in corrosive environments. Thus, it is crucial to understand their susceptibility to stress corrosion cracking (SCC) and the impact of residual stresses. This study investigated the combined effects of applied stress and temperature on the SCC behavior of LPBF SS316L using custom-made C-ring test specimens. Cold-drawn wrought SS316L was included for comparison. Stress relief heat treatment, microhardness testing, partial immersion testing, and microanalysis techniques, such as light optical microscopy (LOM), scanning electron microscopy (SEM), and electron backscatter diffraction (EBSD), were used to quantify the SCC behavior. The outcomes of this study showed that stressed and unstressed LPBF SS316L specimens were highly susceptible to cracking around their printed holes. The SCC susceptibility was attributed to the residual stresses introduced by the printed supports, as both polished and as-printed holes showed similar cracking behavior. This work provides valuable insights and lays a foundation for further research into the impact of using C-ring samples to investigate SCC susceptibility and sheds light on the SCC susceptibility of as-printed components of complex geometry printed with supports due to the influence of residual stresses.