关键词: TC25G钛合金, 双重退火, 热处理, 显微组织, 力学性能

Abstract: Effect of double annealing processes on microstructure and mechanical properties of TC25G titanium alloy rolled bars was investigated. The results indicate that with the increase of the first annealing temperature, the content of primary α phase in the alloy decreases, while the tensile strength and yield strength first decrease and then increase, and the impact absorbed energy first increases and then decreases. As the cooling rate of first annealing increases, martensitic transformation occurs in the microstructure, leading to the increase of strength and the decrease of plasticity and impact property. The microstructure of the alloy subjected to second annealing at different temperatures all exhibits duplex microstructure. With the increase of second annealing temperature, the size of primary α phase and the width of laths in β-transformed microstructure slightly increase, while the strength of the alloy first decreases and then increases, and the impact absorbed energy first increases and then decreases. The optimal comprehensive mechanical properties of the TC25G titanium alloy rolled bars are achieved by double annealing at 940 ℃ for 1 h, air cooling and 570 ℃ for 4 h, air cooling.

Key words: TC25G titanium alloy, double annealing, heat treatment, microstructure, mechanical properties