中文摘要：

利用Gleeble-3800热模拟实验机,在应变速率在0.001~1 s-1以及变形温度在750~950℃范围内对Ti555211合金进行等温恒应变速率压缩实验。本工作基于位错变化密度的内变量方法建立了Ti555211合金热变形本构模型,通过真应力-真应变曲线分析了变形温度和变形速率对流变应力和微观组织的影响规律。结果表明：所建立的本构模型与实验值的平均相对误差为15.25%,相关系数为0.94277,从而为制定新型Ti555211近β钛合金锻造工艺提供科学的理论依据。

英文摘要：

Isothermal compression tests of Ti555211 titanium alloy has been conducted on a Gleebe-3800 hot-simulator at the strain rate ranging from 0.001 to 1 s-1 and the deformation temperature ranging from 750 to 950 ℃. A constitutive model using dislocation density rate as an internal state variable has been proposed for hot working of Ti555211 titanium alloy. According to the isothermal compression test curves, the influence of deformation temperature and stain rate on stress has been investigated. The results show that the correlation coefficient （R） and the average absolute relative error （AARE） for the constitutive model using dislocation density rate as an internal state variable are found to be 0.94277 and 15.25%, respectively, which provide a guide for process optimization and control of near β deformation of Ti555211 titanium alloy.