Microstructure and constitutive model of high-temperature deformation in new-type TB17 titanium alloy

Thermal simulation compression tests are conducted on a new type of ultra-high strength and toughness TB17 titanium alloy using Gleeble-3500 thermal simulation testing machine under the conditions of deformation temperature ranging from 795 ℃ to 895 ℃ and strain rate of 0.001 s⁻¹ to 1.0 s⁻¹. The microstructure and plastic flow behavior of the alloy during hot deformation are analyzed, and a constitutive model of flow stress is established. The results show that the flow stress of the alloy increases rapidly with the increase of strain, then decreases slightly, and finally tends to be stable. Partial dynamic recrystallization occurs in the alloy, dominated by dynamic recovery, and the slight decrease in flow stress is related to the partial dynamic recrystallization of the alloy. Dynamic recrystallization volume fraction of the alloy is not higher than 40%, and the dynamic recrystallization mechanism is mainly dominated by the bowing mechanism. A constitutive model based on the Arrhenius equation is constructed, and the deformation activation energy Q value of the alloy at the temperature of 795-895 ℃ is obtained as 205.48 kJ/mol. The model has high prediction accuracy, with average error δ_avg of 3.987% and correlation coefficient R of 0.9972. The construction of this model provides an accurate prediction for the flow stress of TB17 titanium alloy during hot deformation and also offers a reference for the establishment of high-precision constitutive models for other alloys.