在变形温度为750～950 ℃、应变速率为0.1～0.001 s-1下进行Ti2AlNb合金高温拉伸试验, 研究了温度和应变速率对其抗拉强度和伸长率的影响, 建立了高温变形条件下的应力-应变本构模型。结果表明: Ti2AlNb合金是温度和应变速率敏感性材料, 随着温度的升高或应变速率的降低, 合金的抗拉强度下降, 伸长率升高; 通过修正Hooke定律和Grosman方程所建立的Ti2AlNb合金热成形本构方程, 其计算得到的流变曲线和试验曲线较吻合, 可用于表征Ti2AlNb合金的高温变形行为。

High temperature tensile test of Ti2AlNb alloy was carried out at different temperatures between 750 and 950 ℃ and at different strain rates between 0.1 and 0.001 s-1. The influences of temperature and strain rate on the tensile strength and percentage elongation of the alloy were also studied, and then the stress-strain constitutive model of the alloy under the condition of high temperature deformation was established. The results show that the Ti2AlNb alloy was a kind of temperature sensitive and strain rate sensitive material. With the increase of the deformation temperature or decrease of the stain rate, the tensile strength of the alloy decreased and percentage elongation increased. The heat forming constitutive model of Ti2AlNb alloy was established based on the modified Hooke′s law and Grosman correction equation. The calculated flow curve of the model matched the experimental curve well, indicating that the constitutive model can be used to characterize the deformation behavior of the alloy.