Additive manufacturing of Ti-6Al-4V lattice structures with high structural integrity under large compressive deformation

Additively manufactured Ti-6Al-4V lattice structures have found important niche applications. However, they often show insufficient compressive ductility or insufficient structural integrity. In this study, a batch of 45 octahedral Ti-6Al-4V lattice structures was manufactured in three different strut diameters (0.5, 1.0, 1.5 mm) by selective electron beam melting (SEBM). The influence of post-SEBM annealing on the compressive deformation characteristics of the lattice structure was investigated. The as-built Ti-6Al-4V lattices fragmented when the compressive strain reached 13%-23% depending on strut diameter. Annealing at 950 degrees C (beta transus temperature: 995 degrees C) only slightly improved the compressive ductility of the lattice structures. However, annealing at 1050 degrees C (beta-annealing) fundamentally changed the compressive deformation mode of the lattice structures. The resultant compressive stress-strain curve was featured by a long smooth plateau and no facture occurred even after significant densification of the lattice structure had taken place (>50% of compressive strain). (C) 201 8 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.