TC4钛合金超塑成形流变行为

Flow behavior of TC4 titanium alloy during superplastic forming

针对TC4钛合金超塑成形过程中的流变行为、表征及其应用进行了研究。首先,通过恒应变率高温拉伸试验获得TC4钛合金在高温下的流变行为,发现动态回复主要作用于低应变率的变形,动态再结晶主要作用于高应变率下的应力软化机制。此外,建立一套修正的本构模型用以表征材料的高温流变行为,预测值与试验值之间的平均相对误差为13.09%,证实该本构模型适应于表征钛合金超塑成形的应力-应变关系。最后,基于本构模型,结合ABAQUS有限元软件的CREEP蠕变子程序,考虑应变补偿的影响,开发了一种针对TC4钛合金高温超塑行为数值模拟的方法。以高温拉伸试验为研究对象,分别针对数值模拟应变率、应力和应变结果进行分析,验证了该方法的有效性。

The flow behavior,characterization and application of TC4 titanium alloy during superplastic forming were studied.Firstly,the flow behavior of TC4 titanium alloy at high temperature was obtained by high temperature tensile tests with constant strain rate.It is found that dynamic recovery(DRV) mainly acts on the deformation at low strain rate,and dynamic recrystallization(DRX) mainly acts on the stress softening mechanism at high strain rate.In addition,a modified constitutive model was established to characterize the material flow behavior at high temperature.The mean relative error between the predicted values and test values is 13.09%.It is confirmed that the constitutive model is suitable for characterizing the relationship of stress-strain of titanium alloy during superplastic forming.Finally,based on the constitutive model and combined with the CREEP subroutine of ABAQUS,considering the effect of strain compensation,a numerical simulation method for high temperature superplastic behavior of TC4 titanium alloy was developed.Taking the high temperature tensile test as research object,the simulation results of strain rate,stress and strain were analyzed,and the validity of the method was verified.