基于位错演化的TC18钛合金热变形过程中的流变行为分析

Analysis on Flow Characteristics during High Temperature Deformation of TC18 Titanium Alloy Based Dislocation Evolution

通过热模拟压缩试验研究了TC18合金位错密度的变化。根据位错密度变化对再结晶类型的影响,提出判断钛合金高温塑性变形时流变特征的条件,研究了变形温度与应变速率对流变特性的影响。同时建立大变形条件下钛合金稳态流动的一种新的本构关系,并通过TC18钛合金变形量为0.75时的流动应力验证该本构模型。结果表明,判据条件具有较好的适用性,该本构模型预测值与试验结果吻合良好。

The change of dislocation density of TC18 alloy was investigated by thermal simulation compression experiment. According to the influence of the dislocation density on the dynamic recrystallization type, a criterion determining the flow characteristics of titanium alloy during high-temperature plastic deformation was proposed, and then the effects of deformation temperature and strain rate on the flow characteristics were researched. And a new constitutive equation was established for steady flow of titanium alloy under large deformation. And the constitutive model was verified through the flow stress of the TC18 alloy at the deformation of 0.75. The results show that the criterion has better applicability. The model prediction results are in good agreement with the experimental results.