Microstructure and phase transformations of laser deposited high temperature titanium alloy Ti60A

Laser melting deposition with line interlaced scanning mode was utilized to shape the near-alpha high temperature titanium alloy Ti60A thick plate. Microstructure of the titanium alloy featured by slender a lamellae consists of columnar grains with orientated growth characteristics and the grain diameter is not uniform. Solid solution and aging treatments as well as double-annealing treatment were applied in upper α+β phase field of the alloy to study its phase transformation behavior. The results show that regular rod-like α phase and needle-like hexagonal martensite α' could be produced after solution treatment, then α' is decomposed into continuous and ultra-fine α+β lamellae after aging. Double annealing for the alloy would lead to a unique and stable bi-model microstructure consisting of crab-claw-like primary α phase and slight lamellar transformed β phase.