Very-high-cycle fatigue behavior of AlSi10Mg manufactured by selective laser melting: Effect of build orientation and mean stress

•0° built specimens have better VHCF performance than 90° built specimens.•Four failure modes identified for crack initiation in HCF and VHCF.•Mean stress accelerates crack initiation and hence reduces fatigue life.•A model proposed well describes effect of crack initiation on fatigue strength. This paper studies the influence of build orientation and mean stress on the very-high-cycle fatigue (VHCF) behavior of AlSi10Mg fabricated by selective laser melting (SLM). Horizontally built specimens demonstrate better mechanical performance than vertically built specimens. Four crack initiation modes are identified for the specimens in high-cycle fatigue (HCF) and VHCF regimes, namely initiation by lack-of-fusion, initiation by internal pore, initiation with no obvious defect and initiation by tearing. Moreover, it turns out that the mean stress accelerates crack initiation, and hence reduces fatigue life. A model is proposed to describe the effect of crack initiation location on fatigue strength.