TC11钛合金β相区热变形动态再结晶过程的研究

Dynamic Recrystallization Processes During Hot Deformation of TC11 Titanium Alloy in β Field

通过热压缩实验研究了锻态等轴组织的TCll钛合金在1030～1090℃和应变速率0．001～0．1s^-1范围内的流变行为和组织演变。分析了该合金在实验参数范围内变形的应力一应变曲线特征。热变形过程动力学分析获得了应力指数和激活能分别为4．05，172．3kJ·mol^-1，表明该组织的合金在口区热变形主要是位错的滑移和攀移过程。组织观察和电子背散射衍射（Electron Back Scattered Diffraction，EBSD）测试表明，热变形过程中组织演变以不连续动态再结晶过程进行。该过程中，稳态变形再结晶晶粒尺寸是变形温度和应变速率的函数，而稳态变形组织处于部分动态再结晶状态。通过分析该合金特殊的动态再结晶动力学过程，建立了由原始晶粒尺寸修正的Avrami动态再结晶动力学方程。经验证，与实验数据吻合较好。

The hot deformation behavior and microstructure evolution of TC11 alloy with equiaxed starting structure were studied in 1030-1090℃ and strain rate range 0. 001-0.1s^-1 by hot compression tests. Characteristics of stress strain curves of the alloy deformed with the test parameters were analyzed. Kinetics analyses indicate that the stress exponent and deforming activation energy in t3 region are 4. 05 and 172.3kJ.mol^-1 respectively, which indicate that deformation would be dislocation slipping and climbing processes. Microstructure observation and EBSD testing indicate that discontinuous dynamic recrystallization occurred during hot deformation processes. Recrystallized grain size is a function of Z, a temperature compensated strain rate parameter. Based on dynamic recrystallization structure features at steady state, the modified Avrami kinetic model by prior grain size was established. By comparison, the results calculated by the model are identical to that of tests.