TC11钛合金片层组织热变形行为及组织演变

Hot Deformation Behavior and Microstructure Evolution of TC11 Alloy with Lamellar Structure

通过热压缩试验研究了具有初始β转变组织的TC11钛合金在两相区800～980℃和应变速率0.001～0.1 s^-1范围内的热变形行为和组织演变。分析了该合金在试验参数范围内变形的应力-应变曲线特征。动力学分析获得该合金在两相区变形的应力指数和变形激活能分别为4.42和490.8kJ·mol^-1,说明变形主要是位错的滑移和攀移过程。分析变形组织认为,片层组织的球化和弯折是两相区变形应力软化的原因。温度和应变速率严重影响片层组织球化过程的进行,980℃,0.001 s^-1和0.01 s^-1,以及950℃,0.001 s^-1条件下变形有利于片层组织球化过程的充分进行。900～980℃,0.001～0.1 s^-1球化过程中,变形到稳态的等轴α直径与温度补偿应变速率参数Z呈对数线性关系。

The hot deformation behavior and microstructure evolution of TC11 with β-transformed lamellar structure were studied in the temperature range 800 -980℃ and strain rate range 0. 001 -0. 1 s^-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 Controued and deforming activation energies in α ＋ β region are 4.42 and 490. 8kJ · mol^-1 respectively, which indicate that deformation would be occurred by glide and climb of dislocation. Microstructure observation indicates that globularization and kinking of lamellar structure is the reason of flow softening. Deformation temperature and strain rate affect globularization processes severely. Globularization processes will progressed sufficiently at 980℃ ,0. 001 s^-1 or 0.01 s^-1 , and 950℃ ,0. 001 s^-1. Logarithm of equiaxed a diameters at steady state has linear relationship with logarithm of Z parameters during globularization processes at 900 ～ 980℃ and 0. 001 -0. 1 s^-1.