关键词: TA2纯钛, 热变形温度, 微观组织, 力学性能

Abstract: Hot deformation behavior of TA2 pure titanium at low temperature (20 and 250 ℃) and high temperature (550-850 ℃) was studied by hot compression experiments, combined with microstructure characterization, electron backscatter diffraction (EBSD) and X-ray diffraction (XRD) analysis. The results show that the microstructure morphology is significantly affected by the deformation temperature, which is the fragmentated deformation structure at low temperature (20 and 250 ℃), while being the uniform equiaxed grains due to the dynamic recrystallization at medium and high temperature (550-750 ℃), and the coarse grains are formed by grain coarsening at 850 ℃. The EBSD texture analysis further indicates that the grain orientation is gradually developed from random distribution at low temperature to strong texture at high temperature, and the texture intensity reaching a maximum of 6.8 at 850 ℃. The XRD analysis shows that the (1010) and (1120) diffraction peaks continue to increase with the increase of deformation temperature, revealing the process of crystal defect elimination and integrity recovery. The reversal of the relative intensity of the (0002) and (1011) diffraction peaks confirms that different crystal planes act differently in the thermal activation recovery process. In terms of macroscopic mechanical behavior, the flow stress curve is dominated by work hardening at low temperature, which is transformed into dynamic recrystallization softening at medium temperature. Finally, it is dominated by dynamic recovery and grain coarsening at high temperature, showing as stable steady-state flow.

Key words: TA2 pure titanium, hot deformation temperature, microstructure, mechanical properties