Abstract: Effect of different annealing on microstructure and properties of TC25G titanium alloy bars was studied. The results show that the content of primary α phases is very sensitive to the single annealing temperature, and as the single annealing temperature increases, the strength of the alloy increases slowly, and the plasticity increases first and then decreases. With the prolongation of single annealing holding time, the size of primary α phase tends to increase, and the transformation β phase is coarsened gradually, the holding time has a significant impact on plasticity. With the increase of cooling rate, the plasticity decreases obviously and the strength increases obviously. The secondary annealing temperature has an effect on the strength and plasticity of the bar, when the secondary annealing temperature exceeds 600 ℃, the strength increases slightly, while the elongation and reduction of area significantly decrease. The secondary annealing temperature has significant effects on the impact property of the alloy. When the secondary annealing temperature exceeds 600 ℃, the impact property cannot meet the requirements compared to ≥24 J specified in the technical conditions. When the secondary annealing temperature does not exceed 560 ℃, the impact property is significantly improved, meeting the technical requirements.

Key words: TC25G titanium alloy, annealing, microstructure, mechanical properties, strong plastic matching