TA15 titanium alloy has moderate room temperature strength and high temperature strength, good thermal stability and welding performance, and is mainly used for welding bearing parts of aircrafts and engines that work long hours below 500℃. The nominal composition of the TA15 titanium alloy is Ti-6Al-2Zr-1Mo-1V, in which the aluminum equivalent is 6.33 and the molybdenum equivalent is 1.67, which belongs to the high-aluminum equivalent near-α alloy. TA15 titanium alloy is generally used in the annealed state. With the application of TA15 titanium alloy parts to bear impact loads on aircraft, the stress and deformation caused by instantaneous impact are much larger than those under static load. Therefore, the impact performance of the material has attracted people’s attention.
At 810～850℃, the impact performance of TA15 titanium alloy decreases with the increase of heat treatment temperature; at the same temperature, the impact performance increases with the extension of the holding time, and the impact performance increases with the increase of heat treatment temperature. The amplitude becomes larger. It shows that TA15 titanium alloy bar can obtain higher impact performance after AC heat treatment at 810℃×2h, and improve its impact performance by 35%. When the shape and size of the primary α phase of the TA15 titanium alloy are basically the same, the shape and size of the secondary α phase have a greater influence on the impact toughness. The impact value when the secondary α is strip-shaped is significantly higher than that when the secondary α is round or short rod-shaped.
Effect of Double Annealing on BT25 Titanium Alloy