Alleviating plastic anisotropy of boron modified titanium alloy by constructing layered structure via electron beam directed energy deposition

Abstract

It is widely known that the coarse columnar grains and grain boundary α phases are inevitably formed during the wire-based additive manufacturing (AM) process, which usually lead to the performance anisotropy and deterioration of mechanical properties. In this study, a layered structure was built via alternately depositing Ti-6Al-4 V layers and boron-modified Ti-6Al-4 V layers based on dual-wire electron beam directed energy deposition (EB-DED). It was demonstrated that the anisotropy of mechanical properties effectively was reduced. The tensile test results showed that the anisotropy of ultimate tensile strength and fracture elongation of the layered structure were relatively lower compared with those reported for the homogeneous titanium alloys prepared with the same process. Quasi-isotropic mechanical properties were obtained for the as built layered structures. Additionally, the products with layered structures indicated a good match between tensile strength and plasticity. This work provided a new perspective for the exploration of preparing titanium alloy with isotropic high performance by AM, and may further broaden the application range of additive manufacturing titanium alloys.