Influence of layer-wise fabrication and surface orientation on the notch fatigue behavior of as-built additively manufactured Ti6Al4V

Design and qualification of load-bearing metal parts produced by the additive manufacturing technology is a critical issue. Such metal parts are complex in geometry with notches that are critical locations under fatigue loading. Notch surfaces are typically in the as-built state because post-fabrication surface finishing is not a viable approach in most applications. Here the combined effect of an as-built surface and of a geometrical notch on the fatigue behavior of L-PBF Ti6Al4V was investigated using a new test methodology. Notches of different severity in specimens manufactured according to different directions with respect to the build direction were considered. The intrinsic as-built surface roughness of L-PBF process combined with the layer-wise fabrication of curved notch surfaces resulted in a surface quality strongly affecting notch fatigue behavior. An original interpretative framework of the notch fatigue behavior of L-PBF Ti6Al4V is proposed and discussed.