基于内变量的近β Ti-7Mo-3Al-3Nb-3Cr钛合金热变形本构模型

Internal-state-variable based constitutive modeling for near β Ti-7Mo-3Al-3Nb-3Cr alloy during hot deformation process

摘要:

本文针对近β钛合金提出了一种以位错密度变化率作为内变量的热变形本构模型，该模型同时考虑了溶质元素的固溶强化作用和位错之间的交互作用对流变应力的影响。将该模型应用于一种新型近β钛合金Ti-7Mo-3Al-3Nb-3Cr (Ti-7333)，并采用基于目标优化的遗传算法定量确定了Ti-7333合金的本构模型参数。模型计算的结果表明，利用该热变形本构模型计算出的流变应力与实验数据间的平均相对误差为7.2%，采用基于位错密度变化率的近β钛合金本构模型能够有效地表征Ti-7333合金的流变行为。

Abstract:

A constitutive model using dislocation density rate as an internal state variable has been proposed for hot working of near β titanium alloy in this paper. In the constitutive equations, the effects of solution strengthening and dislocation interaction on flow stress were included. Based on the internal-state-variable based model, the constitutive relationship of a new near β titanium alloy Ti-7Mo-3Al-3Nb-3Cr (Ti-7333) for high temperature deformation was established. And the model parameters were obtained by the genetic algorithm based objective optimization method. Calculating results show that the average relative difference between the calculated and the experimental ?ow stress is about 7.2%. Note that the developed internal-state-variable based constitutive model can efficiently characterize the flow behavior of Ti-7333 alloy.