Ti55531钛合金本构方程及动态再结晶模型建立

Establishment of constitutive equation and dynamic recrystallization model for Ti55531 titanium alloy

根据Ti55531钛合金在变形温度730~900℃、应变速率0.001~10 s^(-1)条件下的等温压缩实验数据,采用线性回归方法对流变应力、应变速率和变形温度之间的关系进行拟合,建立了Ti55531钛合金Arrhenius型本构方程,得到了Ti55531钛合金的热变形激活能为288849.2 J·mol^(-1)。将通过本构方程得到的峰值应力计算值与实验值进行对比和计算,得出峰值应力计算值与实验值的平均相对误差为7.44%,平均相对误差较小,所建立的本构方程能够较好地反映Ti55531钛合金的热变形行为特征。通过进一步对压缩实验数据进行回归分析,得到了Ti55531钛合金动态再结晶过程的临界应变模型、体积分数模型和晶粒尺寸模型。为了验证动态再结晶模型,采用有限元方法对热压缩实验过程进行了模拟,模拟结果和实验结果吻合较好。

According to the isothermal compression experimental data of Ti55531 titanium alloy at deformation temperatur of 730-900 ℃and strain rate of 0. 001-10 s^(-1),the relationship between flow stress,strain rate and deformation temperature was fitted by linear regression method,and the Arrhenius constitutive equation of Ti55531 titanium alloy is established. The obtained hot deformation activation energy of Ti55531 titanium alloy is 288849. 2 J·mol^(-1). The calculation value obtained by constitutive equation and experimental value of peak stress were compared and calculated,and it is obtained that the average relative error between calculation value and experimental value of peak stress is 7. 44%. The average relative error is lesser. The established constitutive equation can reflect the characteristic of hot deformational behavior of Ti55531 titanium alloy well. Furthermore,the critical strain model,volume fraction model and grain size model during dynamic recrystallization process of Ti55531 titanium alloy were obtained by the regression analysis of compression experimental data. To validate the dynamic recrystallization model,the finite element method was used to simulate the hot compression experiment process. The simulation results are in good agreement with the experimental results.