Effect of single annealing on microstructure and mechanical properties of BTi-6431S titanium alloy

The effects of single annealing on the microstructure and mechanical properties of BTi-6431S titanium alloy were studied by OM, EPMA and tensile test. The results show that, with increasing annealing temperature, the primary α phase becomes coarse, then changes into equiaxed shape, and its volume fraction decreases gradually, while the volume fractions of β phase and secondary α phase increase. With elevating the annealing temperature, the room temperature strength increases at first and then decreases, while the high temperature strength increases gradually, but the room-temperature and high-temperature ductility decreases. After annealing at 980°C, BTi-6431S alloy acquires good strength at high-temperature and plasticity at room-temperature. The ultimate tensile strength at 650°C can reach more than 600 MPa, and the room-temperature elongation is more than 8%.