Correlation between microstructure and cyclic behavior of 316L stainless steel obtained by Laser Powder Bed Fusion

In this work, stainless steel 316L obtained by Laser Powder Bed Fusion (L-PBF) has been produced and characterized. The experimental campaign focuses on the samples in the as-built state under cyclic tension-compression loadings. Low cycle fatigue (LCF) and high cycle fatigue (HCF) tests are carried out. Microstructure observations are performed before and after the loadings. As-built L-PBF 316L has a good LCF performance despite the presence of surface defects but a low fatigue limit in the HCF regime. Removing the surface roughness has a beneficial effect but does not improve the fatigue strength to that of machined wrought 316L. Observations on the microstructure of fatigue samples indicate that LCF is dominated by the local plastic deformation, which is mostly achieved by the slip in the studied material and is not sensitive to the defect. The lack-of-fusion defect impairs the fatigue resistance in the HCF regime.