基于微结构演化的V5Cr5Ti合金塑性本构模型

为合理描述V5Cr5Ti合金的塑性变形行为，本文建立了基于微结构演化的塑性本构模型。首先，采用小尺寸试样开展了V5Cr5Ti合金单轴拉伸试验，并对其在不同应变程度下的微结构演化特征进行了分析。研究发现，影响V5Cr5Ti合金塑性变形行为的主要因素是位错密度演化以及团簇状和弥散析出相。据此建立了位错密度演化方程、组分相含量体积分量演化方程，并考虑团簇状和弥散状第二相对V5Cr5Ti合金流动应力的影响，进一步建立了包括非热应力、热激活应力和弥散相强化应力的流动应力关系式。最后，根据隐式应力更新算法对新模型进行了有限元实现，并与实验结果进行比较，验证了新模型的合理性和预测精度。

Microstructure evolution-based plasticity model for V5Cr5Ti alloy

In order to accurately describe and predict the plastic deformation of V5Cr5Ti alloy, a microstructure evolution-based constitutive model was established. Miniaturized specimens of V5Cr5Ti alloy are used to carry out a series of uniaxial tensile tests by pulling up to different strain levels. Microstructural evolution analyses are then performed in order to capture the physical mechanisms and dominating its plastic deformation. It is found that the evolutions of dislocation density and second phase are the main factors affecting plastic deformation behavior of V5Cr5Ti alloy. Based on these observations, the equations of dislocation density evolution and that of flow stress which involves non-thermal stress, thermal activation stress and dispersive phase strengthening stress are developed, using microstructure evolution information. The new model is then numerically implemented using finite element method through an implicit stress update algorithm. The validity and prediction accuracy of the model are finally checked and verified by comparing to the experimental results and that of other conventional constitutive models.