Abstract: Effects of solution treatment temperature and aging temperature on microstructure and shear strength of TC4 titanium alloy were studied by SEM and material testing machine. The results show that comparing the microstructure of the aviation bolts made of the TC4 titanium alloy at different regions including the head center, head edge, R, and bolt core, it is found that due to the faster cooling rate of the head edge compared to the center, where the content of secondary α phase transformed from β phase is higher, and the grain aggregation and growth are more obvious. At the solution temperature of the β single-phase zone, the bolt core and other internal areas are distributed with crisscross martensite, and the dispersion strengthening effect is better. In the solution treatment temperature range of 800-1020 ℃, the shear strength basically increases with the increase of solution treatment temperature. When the solution treatment temperature is 1020 ℃, the shear strength first increases and then decreases with the increase of aging temperature, and the shear strength of the TC4 titanium alloy is the highest after solution treatment at 1020 ℃ and aging at 538 ℃.

Key words: solution treatment temperture, aging temperature, TC4 titanium alloy, bolt, microstructure, shear strength