TB6钛合金β区变形的动态再结晶动力学

使用圆柱形TB6钛合金试样在Thermecmaster-Z型热模拟试验机上进行热模拟压缩实验(变形温度为825~1100℃，应变速率为0.001~1 s^-1)。对采集的流变数据进行加工硬化率处理，确定动态再结晶体积分数，研究了TB6钛合金β区变形的动态再结晶动力学。结果表明，流变应力随着变形温度的降低或应变速率的提高而增大，流变曲线呈现出动态再结晶类型的特征。随着应变速率的降低和变形温度的提高，动态再结晶的体积分数和晶粒尺寸增大。在变形温度高于950℃、应变速率低于0.001 s^-1条件下，动态再结晶的晶粒严重粗化。动态再结晶动力学曲线经历缓慢增加—快速增加—缓慢增加三个阶段，呈现出典型的“S”型特征。确定了动态再结晶的体积分数达到50%时的应变，建立了TB6钛合金的动态再结晶动力学模型。

Kinetics of Dynamic Recrystallization of TB6 Ti-Alloy During Hot Compressive Deformation atTemperatures of β-phase Range

Hot compression tests of as-forged Ti-alloy TB6 were conducted via thermecmaster-Z hot simulation test machine through rapid heating the alloy up to the temperature range for the presence of β-phase and then compression tests by strain rates of 0.001~1 s^-1 at temperatures in the range of 825~1100℃, while the dynamic recrystallization (DRX) volume fraction were acquired by processing the collected rheological data during compression deformation with work hardening rate approach, then the kinetics of DRX of the alloy deformed at β-phase temperature was studied. The results show that the stress increases with the decrease of deformation temperature or the increase of strain rate, and the stress-strain curves present the type of DRX. With the decrease of strain rate and the increase of deformation temperature, the DRX volume fraction and the grain size of dynamic recrystallization increase. The DRX grain coarsening is observed for the alloy deformed at temperatures above 950℃ and strain rates below 0.001 s^-1. The DRX kinetics curves possess three typical stages: slow increase-fast increase-slow increase, showing a typical "S" type characteristic. Furthermore, the strain corresponding to the presence of 50% DRX volume fraction was determined and the relevant DRX kinetics model of TB6 Ti-alloy is established.