Role of local recrystallization behavior on fatigue performance of SLMed 304L austenitic stainless steels

The fatigue performance has always been the key problem hindering the development of disruptive additive manufacturing (AM) technology. We recently found the stored energy induced by SLM process and cyclic strain during fatigue testing can trigger grain boundary migration and local recrystallization behavior. In addition, the junctions between the recrystallized grain tribes and the original coarse grains can lead to the plastic strain localization, promoting the fatigue crack initiation during cyclic deformation, seriously affecting the fatigue lifetime of SLMed 304L SS. Therefore, this study carried out a series of microstructural characterizations to investigate the formation mechanisms of local recrystallization and the role of local recrystallization on the fatigue performance of SLMed 304L SS, which can advance the current understanding of fatigue failure mechanisms of additively manufactured materials. The experimental results show that the detrimental effect of local recrystallization during cyclic deformation on fatigue properties of SLMed 304L SS exceeds that of small pores.