Wire-Arc directed energy deposition of metastable-β alloy Ti-15 V-3Cr-3Sn-3Al using thick wire feedstock: Microstructure and mechanical response☆

Ti-15V-3Cr-3Sn-3Al is a metastable-β alloy initially developed to improve cold formability and reduce downstream processing costs compared to hot-forming Ti-6Al-4V. It is primarily used in sheet and welded forms, with
secondary applications in castings and forgings. However, high formulation costs and strict process windows
reduce expected cost benefits. This study explores an alternative manufacturing route for large-scale components
using the available thick wire format (Ø3.0 mm). Ti-15V-3Cr-3Sn-3Al was deposited via plasma-based wire-arc
directed energy deposition. Samples were evaluated in two conditions: (1) solution-treated (2) solution-treated
and aged. Mechanical testing included tensile and hardness measurements, while microstructural analysis used a
broad range of techniques. Deformation behaviour and fracture surfaces were also examined. The β-phase
microstructure in the as-built condition contained αGB at grain boundaries, which dissolved during solution
treatment, leaving a fully β-phase matrix. Aging resulted in the precipitation of fine α-laths, providing expected
strengthening. In this condition, the material achieved an ultimate tensile strength > 1150 MPa and failure
strain > 6 %, with anisotropy observed only in ductility. In the solution-treated condition, continuous softening
was observed during tensile testing. This study provides insight into properties of Ti-15V-3Cr-3Sn-3Al in additive
manufacturing, laying the groundwork for alternative processing routes for titanium alloys.