Beschreibung:
Two-phase titanium alloy Ti-6Al-2Sn-4Zr-6Mo (TC19) has an excellent application prospect in aviation field. In order to study the hot deformation behavior and microstructure evolution mechanism of TC19 titanium alloy, hot compression tests were carried out at temperatures of 800-1050°C with strain rates of 0.001-10s -1 . The flow behavior of the alloy was predicted by the constitutive models, and the correlation coefficient between the experimental value and the predicted value was calculated. The hot processing map of TC19 alloy was drawn according to the dynamic material model (DMM) theory, and the peak efficiency of energy dissipation region occurred in the temperature range of 850-1000°C with the strain rate of 0.001-0.1s -1 . The main deformation mechanisms were dynamic recovery (DRV) and dynamic recrystallization (DRX). The region of deformation instability was concentrated in high strain rate. The main deformation mechanisms in the structure were deformation band (DB), flow localization (FL), and recrystallized grains produced by continuous dynamic recrystallization (CDRX). Deformation mechanism of TC19 alloy was mainly controlled by the deformation rate through the analysis of EBSD. When the deformation rate was low, the deformation mechanism was mainly DRV and the strain-induced grain boundary migration led to the bulging of the grain boundary and results in discontinuous dynamic recrystallization (DDRX) with the increasing deformation rate. Furthermore, the sub-grain rotated continuously to transform low angle grain boundaries (LAGBs) into high angle grain boundaries (HAGBs) at the high deformation rate, and recrystallized grains packed with HAGBs were observed in the microstructure. The mechanism was further confirmed by TEM technique and the existence of ω phase in the precipitated phase observed by diffraction pattern, which indicated dynamic phase transition may occur during hot deformation