Comparison of the High Cycle Fatigue Behavior of Ti–6Al–4V Produced Respectively by EBM and Hot-Rolling

Abstract

In this study, the microstructure, texture, and mechanical properties of Ti–6Al–4V(Ti-64) alloy produced by electron beam melting (EBM) and rolling were comparatively researched. The results showed that the microstructure of EBM Ti-64 consisted of columnar β grains growing epitaxially along the build direction. The c axis of α grains was oriented along the build direction, and the intensity was about 27 times random. The plate Ti-64 consisted of about 60 vol% of αp and 40 vol% of βT. The c-axis of α grains were parallel to the transverse direction of the plate and the texture strength was 5 times random. The tensile strength of EBM Ti–6Al–4V material was lower than that of the plate, but the ductility was higher. The EBM material exhibited a much larger variation of strength and ductility. This is because of the finer microstructure in the EBM material and also the microtextured regions in the plate material. The cracks in the plate material all initiated from the surface area but cracks in the EBM material occurred both on sample surface and in interior. The smaller lamellar thickness in the EBM material reduces the dislocation slip length, thus improves the life during the crack initiation stage.