Fatigue Life Enhancement of Binder Jet Manufactured Bronze Infiltrated 316L by Severe Shot Peening

This study was initiated to investigate the material characteristics of binder jet (BJ) manufactured austenitic stainless steel 316L, focusing specifically on the less studied bronze infiltrated version of this material. While BJ technology offers a compelling alternative to the current market leader laser powder bed fusion, all additive manufacturing methods are susceptible to porosity, which adversely affects the fatigue properties of parts, resulting in inferior fatigue life compared to traditionally manufactured counterparts. In this study, we explore the novel application of severe shot peening (SSP) as a post-processing method to enhance fatigue life. Through comprehensive microstructural analysis utilizing EBSD, mechanical properties testing via tensile testing, and fatigue life analysis using flexural bending fatigue testing, we demonstrate that SSP treatment induces surface modification, leading to increased material strength albeit with a trade-off in ductility. Moreover, our findings reveal a significant improvement in the fatigue life of the material. Utilizing SSP, we observed that the fatigue limit of the material more than doubled, surpassing the performance of the sheet metal counterpart of the same material. These results underscore the potential of SSP as an attractive method for property enhancement in additive manufacturing.