(1. 中南大学 粉末冶金国家重点实验室，长沙 410083；2. 中南大学 冶金科学与工程学院，长沙 410083；
3. 湖南金天钛业科技有限公司，常德 410007)
摘 要: 在Gleeble-1500 热模拟机上对Ti-5Al-5Mo-5V-1Cr-1Fe合金进行高温热压缩实验，研究该合金在变形温度为750~900 ℃、应变速率为0.001~1 s−1 条件下的流变应力行为。利用光学显微镜分析合金在不同变形条件下的组织演化规律。结果表明：合金的流变应力随着应变速率的增大和变形温度的降低而增大；流变应力随着应变的增加而增大，出现峰值后逐渐趋于平稳；变形过程中的流变应力可用Arrhenius双曲正弦本构关系来描述，平均变形激活能为454.2 kJ/mol；各种变形条件均可细化原始晶粒尺寸。随着温度的升高和应变速率的降低，合金的主要软化机制由动态回复逐渐变为动态再结晶；在(α+β)相区变形(750~850 ℃)时，α相对β晶粒的动态再结晶的发生起到阻碍作用。
关键字: Ti-5Al-5Mo-5V-1Cr-1Fe合金；热变形；流变应力；显微组织
（1. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China;
2. School of Metallurgical Science and Engineering, Central South University, Changsha 410083, China;
3. Hunan Goldsky Titanium Industry Technology Co. Ltd., Changde 410007, China）
Abstract:The hot deformation behaviors of Ti-5Al-5Mo-5V-1Cr-1Fe alloy were studied by a Gleeble-1500 machine at 750−900 ℃ with the strain rate of 0.001−1 s−1. The microstructural evolution of the alloy was investigated by optical microscopy. The results indicate that the flow stress of the alloy increases with increasing strain rate and decreasing deformation temperature. The flow stress increases with increasing strain until the stress reaches the peak value, then the flow stress remains constant. The flow stress in deformation can be described by Arrhenius hyperbolic sine constitutive equation, and the average activation energy is 454.2 kJ/mol. The original grain size can be refined under all deformation conditions. The main softening mechanism is changed from dynamic recovery to dynamic recrystallization with increasing the deformation temperature and decreasing the strain rate. In the (α+β) region (750−850 ℃), α phase can inhibit the dynamic recrystallization of β grains particles during deformation.
Key words: Ti-5Al-5Mo-5V-1Cr-1Fe alloy; hot deformation; flow stress; microstructure
