TC4钛合金电辅助拉伸行为及本构模型

Electro-Assisted Tensile Behavior and Constitutive Model of TC4 Titanium Alloy

摘要:

对TC4钛合金进行了高温及电辅助拉伸实验，其中变形温度为600~900 ℃，电流密度为14~22 A/mm2。探究了温度及电流密度对合金流动应力的影响规律。结果表明，在热拉伸过程中材料的流动应力随着温度的升高而降低，延伸率与温度呈正相关。当施加脉冲电流后材料流动应力下降，延伸率随电流密度的升高表现为先升后降的变化趋势。最后基于拉伸真应力-真应变数据，在初始Johnson-Cook模型框架的基础上，构建了耦合热效应与非热效应的多物理场本构模型，采用回归拟合的方法确定了本构模型参数，并将实验值与预测值进行误差分析。结果表明，本构模型的确定系数R²≥0.95，平均相对误差MRE<2.5%，在宽域工艺参数范围内具有较好预测能力。本研究旨在为钛合金的电辅助成形提供理论依据，并为优化成形工艺参数提供参考。

Abstract:

High-temperature and electro-assisted tensile experiments were conducted on TC4 titanium alloy, with the deformation temperature of 600?900 ℃ and the current density of 14?22 A/mm². The effects of temperature and current density on the flow stress of the alloy were investigated. The experimental results show that during the hot tensile process, the flow stress of the material decreases with the increase in temperature, and the elongation is positively correlated with temperature. The flow stress of the material decreases after applying pulsed current, and the elongation first increases and then decreases with the increase in current density. Finally, based on the true stress-true strain data of tension, a multi-physical field constitutive model coupling thermal and athermal effects was constructed on the basis of the original Johnson-Cook model framework. The constitutive model parameters were determined by the regression fitting method, and error analysis was performed between the experimental and predicted values. The results show that the coefficient of determination R² of the constitutive model is more than 0.95, the mean relative error is less than 2.5%, which indicates that the model has relatively good predictive ability within a wide range of process parameters. The research aims to provide a theoretical basis for the electro-assisted forming of titanium alloys and a reference for optimizing forming process parameters.