BT25钛合金β相区动态再结晶行为及数值模拟

Dynamic Recrystallization Behavior and Numerical Simulation of β Phase of BT25 Titanium Alloy

利用Gleeble-3500型热模拟试验机对BT25钛合金进行单道次等温压缩实验,分别采用Najafizadeh-Jonas加工硬化率模型和Cingara-McQueen流变应力模型研究了合金在变形温度1040~1100℃,应变速率0.001~1 s^(-1)和最大压下率为60%的条件下动态再结晶的临界条件,分析真应力-真应变曲线,计算加工硬化率并建立了临界应变模型;同时通过线性回归法计算材料参数,构建JMAK动态再结晶动力学方程,并采用该模型模拟了BT25钛合金在热变形过程中动态再结晶行为。结果显示:流动应力表现出对应变速率和变形温度非常敏感;高温和低应变速率有利于DRX发生;有限元模型对DRX体积分数的预测误差在10%以内。该模型具有良好的预测能力,为工业生产中塑性变形和微观结构的预测提供了有效的工具。

The single-pass isothermal compression test of BT25 titanium alloy was carried out by Gleeble-3500 thermal simulation machine.Najafizadeh-Jonas model of working hardening rate and Cingara-Mc Queen model of flow stress were used to study the critical conditions of dynamic recrystallization under the conditions of deformation temperature of 1040~1100℃,strain rate of 0.001~1 s^(-1) and maximum height reduction of 60%.The true stress-true strain curve was analyzed,and the critical strain model was established.At the same time,JMAK dynamic recrystallization(DRX)kinetic equation was constructed by calculating material parameters and linear regression method.A numerical simulation model was developed to simulate the dynamic recrystallization behavior of BT25 titanium alloy during thermal deformation.The results show that the flow stress is sensitive to the strain rate and deformation temperature.High temperature and low strain rate are favorable for DRX.The prediction error of the finite element model for predicting DRX volume fraction is less than 10%.The model has good prediction ability and provides an effective tool for predicting plastic deformation and microstructure in industrial production.