Defects tolerance and fatigue limit prediction for laser powder bed fusion Ti6Al4V

This study is focused on the individual effect of gas porosity size and location on fatigue strength of a laser powder bed fusion Ti6Al4V alloy. Tensile and fatigue samples were manufactured by artificially seeding gas pores either at the centre or close to surface. Seeded porosity reduced the ductility by 20 % and fatigue strength by 33 % but had little influence on the static strength. Despite seeded pores, 50 % fatigue samples had crack initiation from process inherent defects that also caused fatigue data scatter. A modified Kitagawa-Takahashi diagram was established to predict the fatigue strength under the influence of porosity defects.