Abstract: Effect of aging treatment at 450-600 ℃ for 8 h on the microstructure and mechanical properties of solution treated and cold drawn TB9 titanium alloy was investigated. The results show that the microstructure of the TB9 alloy changes significantly with aging temperature. When aged at 450-500 ℃, fine and uniformly distributed α-phase precipitates, which significantly enhances hardness and strength but results in poor plasticity. When aged at 550-600 ℃, the size and volume fraction of α-phase increase, leading to more uniform grain structures. Aging temperature has a significant impact on strength and plasticity. When aged at 450 ℃, strength reaches a peak of about 1700 MPa with nearly zero elongation. As the aging temperature increases, the strength decreases, while the elongation increases. When the aging time is 550 ℃, the strength is about 1400 MPa and the elongation is 14%. At 600 ℃, the strength is 1200 MPa and the elongation is 22%. The tensile fracture characteristics show brittle fracture at lower temperature (500 ℃) and ductile fracture at higher temperature (600 ℃). Therefore, to achieve an optimal balance of strength and plasticity for TB9 titanium alloy, the recommended aging temperature is 550-600 ℃.

Key words: TB9 titanium alloy, aging treatment, microstructure, mechanical properties, tensile fracture