Microstructural and micromechanical evolution during dynamic recrystallization
Microstructural and micromechanical evolution during dynamic recrystallization
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DOI：
10.1016/j.ijplas.2017.09.009
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发表时间：
2018
影响因子：
9.8
通讯作者：
P. Zhao;Yunzhi Wang;S. Niezgoda
中科院分区：
文献类型：
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作者：
P. Zhao;Yunzhi Wang;S. Niezgoda
动态再结晶（DRX）原则上可以作为一种通过单一的热加工路线来控制晶粒结构的替代方法，而不是传统的冷加工，然后在高温下退火;实际上，由于缺乏对该过程的定量理解和预测，其广泛应用受到阻碍。使用最近开发的模型（Zhao等人，2016），它集成了基于快速傅立叶变换的弹粘塑性模型和相场再结晶模型，我们研究了多晶铜在各种高温下单轴压缩过程中微观结构和微观力学场的演变。定量分析的基础上的模拟结果证实，应力重新分布后，形成一个新的晶粒可以显着降低相邻晶粒的位错密度，导致所谓的“DRX增强恢复”，而新的晶粒本身经历加速加工硬化相比，矩阵。数值模拟结果揭示了动态再结晶软化过程中位错密度演化的宏观动力学方程。动态再结晶发生的临界应变和Zener-Hollomon参数服从幂律，模型预测的指数与实验结果一致。Avrami指数的温度依赖性也被预测使用的模拟数据，这与实验结果相一致。的人口的晶界和三重和四重结示出的演变与变形和温度相关。
Dynamic recrystallization (DRX) can in principle serve as an alternative way of controlling grain structure via a single route of hot working instead of the traditional cold working followed by annealing at elevated temperatures; in reality, its widespread application is hindered by the lack of quantitative understanding and prediction of the process. Using a recently developed model (Zhao et al., 2016) that integrates a fast Fourier transform-based elasto-viscoplastic model and a phase-field recrystallization model, we investigate the evolution of both microstructural and micromechanical fields in polycrystal copper during uniaxial compression at various elevated temperatures. Quantitative analysis based on the simulation results confirms that stress redistribution upon the formation of a new grain can significantly lower the dislocation density of neighboring grains, leading the so-called “DRX-enhanced recovery”, while the new grain itself undergoes accelerated work hardening as compared to the matrix. Numerical analysis using current simulation data reveals a macroscopic kinetic equation describing the average dislocation density evolution during DRX softening. The critical strain for the onset of DRX and the Zener–Hollomon parameter are found to obey a power law, with the model predicted exponent being consistent with that found in experiments. Temperature-dependence of the Avrami exponents have also been predicted using the simulation data, which agrees with the experimental finding. The population of grain boundaries and triple and quadruple junctions are shown to evolve with deformation and be temperature-dependent.