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

摘要

Additively manufactured Ti-6 Al-4 V 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-6 Al-4 V 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-6 Al-4 V lattices fragmented when the compressive strain reached 13%–23% depending on strut diameter.Annealing at 950?C(β transus temperature: 995?C) only slightly improved the compressive ductility of the lattice structures. However, annealing at 1050?C(β-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).