Process Mapping, Fracture and Fatigue Behavior of Ti-6al-4v Produced by Ebm Additive Manufacturing

The present work was conducted as part of a larger America Makes funded project to begin to examine the effects of changes in process variables on the resulting microstructure and fracture and fatigue behavior of as-deposited Ti-6Al-4V. In addition to presenting initial results on process mapping of the electron beam powder bed process, the present work also documents the location-dependent properties of the as-deposited materials with respect to the build direction. In the fatigue crack growth tests, the fatigue threshold, Paris law slope, and overload toughness were determined at load ratio, R=0.1, while fatigue precracked samples were tested to determine the fracture toughness. Fracture surface examination revealed the presence of unmelted powders, disbonded regions and isolated porosity, however, the resulting mechanical properties were in the range of those reported for cast and wrought Ti-6Al-4V.