热加工过程中动态再结晶现象的多相场研究
Dynamic recrystallization phenomenon in hot-working process by multi-phase-field model
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摘要: 金属热加工过程中的动态再结晶引起的组织演化难以通过实验实时观察,本文基于Ginzburg-Landau动力学方程,构造多相场法与位错密度计算相耦合的物理模型,模拟了热加工过程中的动态再结晶现象.研究了不同温度和不同应变速率下的动态再结晶过程,阐述了应力.应变曲线由单峰形式转变为多峰形式的原因.此外,本文利用多相场法对多阶段变形过程进行了系统模拟,研究了静态回复对动态再结晶过程的影响,分析了不同的热加工参数对动态再结晶动力学的影响,发现在变形问断过程中,晶粒尺寸不断增大,较高的变形温度和较低的应变速率可以加速动态再结晶过程.Abstract: Evolution of the dynamic recrystallization microstructure in the hot working process of metal is difficult to observe in real time experimentally. Based on Ginzburg-Landau kinetic equation, a physical metallurgy model with coupling multi-phase field method and the dislocation density calculation is used to simulate dynamic recrystallization in the thermal processing. The dynamic recrystallization processes at the different temperatures and different strain rates are investigated. The reason for the stress-strain curve changing from single peak state to the multi-peak state is explained. In addition, we systematically simulate the process of multi-stage deformation and the effect of static recovery on dynamic recrystallization, and analyze the influence of thermal processing parameters on the kinetics of dynamic recrystallization. The simulation results show that the grain size increases during suspension of deformation, and higher deformation temperature and lower deformation strain rate can accelerate the process of dynamic recrystallization.
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