Abstract
Selective laser melting (SLM) of 316L Austenitic Stainless Steels (ASS) using two different machines and powders, resulting in different Volume Energy Densities (VED) were chosen to assess the effect of microstructure and hydrogen on high cycle fatigue properties. Microstructural characterizations reveal notably different grain morphology and texture depending on the building strategy. The density of dislocations and defect density are different for the two builds as a consequence of the differences in the VED. The concentration of hydrogen in the SLM 316L is lower than that of a conventional 316L ASS. The diffusion of hydrogen in inversely proportional to the dislocation density. Vickers microhardness tests showed an increase linear to the hydrogen concentrations. High cycle fatigue tests show improved fatigue properties and less sensitivity to defects for a higher VED. Cathodic pre-charged and insitu-charging fatigue tests do not reveal any effect of hydrogen on the fatigue life of SLM 316L. Various limiting aspects in understanding the high cycle fatigue tests are discussed.