Electron beam welding of laser additive manufacturing Ti-6.5Al-3.5Mo-1.5Zr-0.3Si titanium alloy thick plate

Individually fabrication parts by laser additive manufacturing (LAM) and then jointing them together through electron beam welding (EBW) is a viable way for manufacturing large components with reduction of internal stress. For investigating the microstructure and mechanical property of EBW joint along longitudinal and transverse direction in LAMed component, two LAMed Ti-6.5Al-3.5Mo-1.5Zr-0.3Si plates were successfully welded without defects. Results show that the microstructure of base metal (BM) is a typical basket-weave morphology that exhibits lamellar a within matrix. In heat affected zone (HAZ), the part of primary a transforms to beta with the some very fine lamellar as precipitates out. Due to the fast solidification rate, a large number of acicular alpha' forms in fusion zone (FZ), leading to the highest microhardness. All tensile samples fail in BM region with the fracture type of intergranular dimpled fracture. Compared with the T-joint, the L-joint shows higher ultimate tensile strength and yield strength, but lower elongation and reduction of area due to the morphology of columnar grains and the strong texture of beta<010> parallel to the deposition direction. (C) 2018 Elsevier Ltd. All rights reserved.