ABSTRACT The mechanical properties of metals used as structural materials are significantly affected by hot (or warm) plastic working. Therefore, it is industrially important to predict the microscopic behaviour of materials in the deformation process during heat treatment. In this process, a number of nuclei are generated in the vicinity of grain boundaries owing to thermal fluctuation or the coalescence of subgrains, and dynamic recrystallisation (DRX) occurs along with the deformation. In this paper, we develop a DRX model by coupling a dislocation-based crystal plasticity model and a multi-phase-field (MPF) model through the dislocation density. Then, the temperature dependence of the hardening tendency in the recrystallisation process is introduced into the DRX model. A multiphysics simulation for pure Ni is conducted, and then the validity of the DRX model is investigated by comparing the numerical results of microstructure formation and the nominal stress–strain curve during DRX with experimental results. The obtained results indicate that in the process of DRX, nucleation and grain growth occur mainly around grain boundaries with high dislocation density. As deformation progresses, new dislocations pile up and subsequent nucleation occurs in the recrystallised grains. The influence of such microstructural evolution appears as oscillation in the stress–strain curve. From the stress–strain curves, the temperature dependence in DRX is observed mainly in terms of the yield stress, the hardening ratio, and the change in the hardening tendency after nucleation occurs.

中文翻译：

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基于多相场和位错晶体塑性模型的动态再结晶建模与仿真

摘要用作结构材料的金属的机械性能受热（或温）塑性加工的显着影响。因此，预测材料在热处理变形过程中的微观行为在工业上很重要。在这个过程中，由于热波动或亚晶的聚结，在晶界附近产生了许多晶核，并伴随着变形发生动态再结晶（DRX）。在本文中，我们通过位错密度耦合基于位错的晶体塑性模型和多相场 (MPF) 模型来开发 DRX 模型。然后，将再结晶过程中硬化趋势的温度依赖性引入到 DRX 模型中。对纯 Ni 进行了多物理场仿真，然后通过将微观结构形成的数值结果和DRX过程中的名义应力-应变曲线与实验结果进行比较来研究DRX模型的有效性。结果表明，在DRX过程中，形核和晶粒长大主要发生在具有高位错密度的晶界附近。随着变形的进行，新的位错堆积，随后在再结晶晶粒中发生形核。这种微观结构演变的影响表现为应力-应变曲线的振荡。从应力-应变曲线中，DRX 中的温度依赖性主要在屈服应力、硬化率和形核发生后硬化趋势的变化方面观察到。