The fatigue performance evaluation of additively manufactured 304L austenitic stainless steels

Abstract This study carried out the fatigue tests of selective laser melting (SLM) 304L austenitic stainless steel (SS) made by different scanning speeds. The purpose is to deeply understand the microstructure, fatigue failure process and fatigue failure mechanism of SLMed 304L SS. For this purpose, the microstructure, surface roughness and porosity were tested by field emission scanning electron microscope (FESEM) and electron backscatter diffraction (EBSD), while the residual stress was obtained by μ-X360 residual stress analyzer. In addition, the fatigue failure process of SLMed 304L SS was in-situ monitored through acoustic emission (AE) technique and thermal imager. The results show that SLMed 304L SS has excellent fatigue performance. The ‘critical’ value is defined to distinguish the critical influence of surface roughness and porosity. In addition, the temperature rise caused by the stored energy deriving from the active dislocation motions is affected by the loading direction and scanning direction by regulating the dislocation motions during fatigue testing.