Study on high-temperature constitutive model of TC11 titanium alloy dynamic recovery and dynamic recrystallization

Gleeble-1500 thermal simulation testing machine was used to perform an isothermal constant strain rate uniaxial compression test for TC11 titanium alloy under a deformation temperature of 900~1 050 ℃ and strain rate of 0.1~10 s^-1. The microstructure observation results show that a significant dynamic recrystallization phenomenon occurs in TC11 titanium alloy during the thermal deformation process. Under the deformation temperatures of 900 ℃ and 950 ℃, the recrystallization grain size first increases and then decreases with increasing strain rate. Furthermore, as the deformation temperature reaches 1 000 ℃ and 1 050 ℃, the content of the α phase significantly decreases, and the microstructure evolution is dominated by dynamic recrystallization, accompanied by obvious grain refinement. To study the effect of the dynamic recrystallization phenomenon on rheological behavior, a high-temperature constitutive model of flow stress based on dynamic recovery and dynamic recrystallization was constructed in combination with the K-M dislocation density model and dynamic recrystallization fraction model. By comparing the prediction results of the constitutive model with the test data, the correlation coefficient and average relative error are 0.989 and 6.53%, respectively, which suggests that the constructed flow stress model with dynamic recovery and dynamic recrystallization can accurately predict the flow stress of TC11 titanium alloy under thermal deformation.