摘要
目的 以新型高强韧Ti-6Cr-5Mo-5V-4Al(Ti6554)近β钛合金为对象,探讨脉冲电流对材料变形行为和温度变化的影响规律,揭示Ti6554钛合金在不同电流密度下的位错密度演化规律。方法 对材料进行不同电流密度、占空比、应变速率条件下的电辅助压缩实验,建立考虑位错密度的修正电塑性本构模型,基于ABAQUS进行UMAT子程序开发,建立电-热-力三场耦合有限元模型,模拟Ti6554钛合金电辅助压缩变形过程,并进行实验验证。结果 随着电流密度和占空比增大流动应力减小,随着应变速率增大流动应力也增大;电辅助压缩实验结果与模拟结果相比的平均误差为6.31%,验证了模型的有效性;通过子程序状态变量输出位错密度的变化发现,电流密度为15.92、23.88、27.87、31.88、39.81 A/mm^(2)的位错密度分别下降了15.34%、55.63%、68.23%、83.84%、89.13%,表明位错密度随电流密度的增大而降低。结论 建立了基于位错密度的电塑性本构模型和电-热-力多场耦合的有限元模型,能够模拟Ti6554钛合金的电压缩变形行为,并且表征了位错增殖、位错湮灭及动态回复,获得了其位错密度的演化规律。
The work aims to take new high-strength Ti-6Cr-5Mo-5V-4Al(Ti6554) near-β titanium alloy as the object to explore the effect law of pulsed current on the deformation behavior and temperature change of the material and reveal the dislocation density evolution law of Ti6554 titanium alloy under different current densities. Electrically-assisted compression experiments were carried out on the material under different current densities, duty cycles and strain rates. A modified electroplasticity constitutive model considering dislocation density was established, and a UMAT subroutine was developed based on ABAQUS to establish an electrical-thermal-stress field coupled finite element model to simulate the electrically-assisted compression deformation of Ti6554 titanium alloy and carry out experimental validation. The flow stress decreased with increasing current density and duty cycle, but increased with increasing strain rate. The average error of the stress-strain of the experiment compared with the simulation results was 6.31%, which verified the validity of the model. The dislocation density was output by the subroutine state variable, and it was found that the dislocation density decreased by 15.34%, 55.63%, 68.23%, 83.84%, and 89.13%for the current density of 15.92, 23.88, 27.87, 31.88 and 39.81 A/mm^(2), respectively, indicating that the dislocation density decreased with the increase of current density. Therefore, the electroplasticity constitutive model based on dislocation density and the electrical-thermal-stress field coupled finite element model are able to simulate the electrically-assisted compression deformation behavior of Ti6554 titanium alloy and characterize the dislocation proliferation, dislocation annihilation and dynamic recovery, thus obtaining the evolution law of dislocation density.
作者
周宇杰
刘斌
武川
曲周德
ZHOU Yu-jie;LIU Bin;WU Chuan;QU Zhou-de(National-Local Joint Engineering Laboratory of Intelligent Manufacturing Oriented Automobile Die&Mould,Tianjin University of Technology and Education,Tianjin 300222,China)
出处
《精密成形工程》
北大核心
2023年第1期51-60,共10页
Journal of Netshape Forming Engineering
基金
国家自然科学基金面上项目(52075386)
中国博士后科学基金面上项目(2020M672309)
陕西省高性能精确成形技术与装备重点实验室开放课题(PETE2019KF02)
天津市教委科研项目(2020KJ107)。
关键词
Ti6554钛合金
位错密度
电辅助压缩
电塑性本构
动态回复
Ti6554 titanium alloy
dislocation density
electrically-assisted compression
electroplasticity constitutive model
dynamic recovery
