Influence of the defect size, type, and position on the High Cycle Fatigue behavior of Ti-6Al-4V processed by laser powder bed fusion

The present paper analyzes separately the effect of the features of the typical AM defects on the fatigue resistance of Ti-6Al-4V alloy. To do so, different defect population in terms of sizes and morphologies were obtained by varying the L-PBF process parameters. The distance of these defects with respect to the surface was also controlled. A uniaxial fatigue testing campaign (R =-1) has then been conducted. The results have showed great influence of the nature of the defect population on the fatigue strength of Ti-6Al-4V alloy, for the case of surface crack initiation. The results have also allowed to quantify the criticality of internal defects with respect to their sizes and showed that the defect morphology has no influence on the fatigue strength for the case of internal crack initiation.