Microstructure and mechanical properties of laser solid formed Ti60 alloy

In the present paper, the microstructure and mechanical properties of as-deposited and duplex-annealing treated laser solid formed (LSF) Ti60 alloy at room temperature and 600°C were investigated. It was found that Ti60 alloy is inclined to form equiaxed grains during laser solid forming due to a high proportion of the equiaxed grains in the molten pool and uncompletely remelting when new layer was deposited on prior layer. For the as-deposited sample, the microstructure is composed of Widmanstätten α laths in prior equiaxed β grain. Through duplex-annealing treatment, the continuous prior β boundary was broken up, the α laths have an obvious tendency to coarsen and part of them were spheroidized. The ultimate tensile strength of the as-deposited LSF sample at room temperature and 600°C are both higher than wrought, while the plasticity of room temperature is lower than wrought. The fractography shows toughness fracture character, and the plasticity of 600°C approach those of wrought. The comprehensive mechanical properties of laser formed samples are improved obviously through duplex-annealing treatment.