工业纯钛TA1管材热压缩成型本构方程研究

Study on Constitutive Equation for Thermo-compressive Forming of TA1 Titanium Pipe

利用Gleeble 3500热模拟试验机研究了工业纯钛TA1管材在660~780℃,应变速率为0.1~10 s^-1条件下的热压缩变形行为。利用线性拟合方法确定了材料常数及变形激活能,建立了双曲正弦函数形式本构方程。用Zenner-Hollomon参数对最大应力进行了预测,预测值与试验值能够较好地吻合。试验结果表明:工业纯钛TA1材料的应力-应变曲线表现出显著的加工硬化特征,流变应力随温度的升高而降低,随应变速率的下降而减小。工业纯钛TA1热压缩变形过程中,流变应力受变形温度及变形速率的显著影响;流变应力随温度的升高而降低,随变形速率的下降而减小。

The thermo-compressive deformation behaviors of the TA1 titanium pipe are investigated with the Gleeble 3500 simulator within a temperature range of 660~780℃and strain rate range of 0.1~10 s^-1.A linear fitting method is used to determine the material constants and the deformation activation energy to set up the hyperbolic sine function formal constitutive equation.The maximum stresses are predicted by using the Zenner-Hollomon parameter,showing that the predicted values are preferably in compliance with the tested values.The test result demonstrates that the stress-strain curves of the TA1 material show distinctive feature of work hardening,i.e.,the rheological stress drops along with the rise of the temperature,and mitigates along with the decrease of the strain rate.It is also revealed that during the thermo-compressive deformation process of the TA1 material,the rheological stress is obviously affected by the deformation temperature and the deformation rate,i.e.the rheological stress drops along with the rise of the temperature,and mitigates along with the decrease of the deformation rate.