Effects of heat treatment on the microstructures and mechanical properties of TAl5 titanium alloys by laser solid forming

The effects of heat treatment on the microstructures and mechanical properties of TAl5 titanium alloys fabricated by laser solid forming (LSF) were investigated. The microstructure of the as-deposited sample is composed of Widmanst?tten α+α laths of different orientations, and there is certain anisotropy in the tensile properties of LSFed samples. There is no obvious change in the microstructure by annealing treatment, but the plasticity of LSFed samples is increased obviously accompanied with a little decrease of the tensile strength. The annealed sample presents good comprehensive tensile properties, which can satisfy the tensile properties standard of annealed TA15 wrought. After solution-aging treatment, the microstructure consists of coarse primary α and α', and the strength of LSFed samples is significantly improved. The microstructure of coarse primary α, refined secondary α and α' can be obtained by double solution-aging treatment, which results in a slight decrease in the tensile strength. Compared with room temperature tensile properties, all of LSFed sample in the four kinds of treatment states show a lower strength and a higher plasticity at high temperature. The hardness of LSFed samples is ranged from 30 HRC to 45 HRC for the different heat treatments, and the change trend of hardness after different heat treatments is in agreement with that of tensile strength.