基于微结构演化的V5Cr5Ti合金塑性本构模型

Microstructure Evolution-based Plasticity Model for V5Cr5Ti Alloy

为合理描述V5Cr5Ti合金的塑性变形行为,论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.

To precisely describe the deformation behavior of V5 Cr5 Ti alloy, this work developed a microstructure evolution-based constitutive model of plasticity. The miniaturized specimens of V5 Cr5 Ti alloy were used to perform a series of uniaxial tensile tests at different strain levels under quasi-static conditions, followed by microstructural evolution analysis by metallographic and X-ray spectroscopy techniques to capture the dominant deformation mechanisms. The evolutions of dislocation density and second phase were found to be the key factors affecting the plastic deformation behavior of V5 Cr5 Ti alloy. Based on the microstructural evolution information, the evolution equations of dislocation density and the Ti-enriched second phase were formulated. The flow stress relations including non-thermal stress, thermal activation stress and dispersive reinforcing stress were further established by considering the influence of the second cluster and the dispersive reinforcement phase(the Ti-enriched second phase) of V5 Cr5 Ti alloy. The microstructure evolution-based constitutive model of V5 Cr5 Ti alloy was thus proposed and numerically implemented using the finite element method through ABAQUS user material interface(UMAT) with an implicit stress update algorithm. The validity of the new model was then examined according to the experimental results. The prediction accuracy of the new model was verified by comparing with other conventional models, such as the Johnson-Cook model, the Ramberg-Osgood model and the Zerilli-Armstrong model.