Abstract This paper proposes a grain fragmentation modeling approach that couples continuum dislocation dynamics analysis with a crystal-plasticity framework. The proposed model investigates the microstructural features of FCC metals subjected to severe plastic deformation (SPD) processes. Several aspects of the deformation process were considered in this model, including texture evolution, statistically stored dislocations (SSDs) and geometrically necessary dislocations (GNDs) densities evolution, and grains fragmentation and its effect on the overall mechanical response. The proposed model was applied to a reference volume element (RVE) in which the grains are distributed and assigned an initial position. Within the model, each grain has the ability to split into 1024 new smaller grains, which subsequently leads to strain hardening and grain refinement. The latter was modeled by accounting for the grain-grain interaction, for which the concept of the GNDs is incorporated into the mean free path of the dislocations. GNDs were assumed to be induced by grain boundaries that restrict the free deformation of a grain and result in an increase of stresses leading to the grain size reduction. Our grain fragmentation hypothesis was based on the Toth et al. (2010) lattice curvature assumption [Toth, L.S., Estrin, Y., Lapovok, R., Gu, C., 2010. A model of grain fragmentation based on lattice curvature. Acta Mater. 58, 1782–1794]. The grain refinement procedure was triggered when the misorientation threshold between subgrains was exceeded. The model parameters were calibrated using torsion tests of pure copper material. The simulation results give reliable predictions of the crystallographic texture, the evolution of dislocation density, and the final grain size based on available experimental data.

中文翻译：

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基于连续位错动力学的晶粒破碎建模，

摘要 本文提出了一种将连续位错动力学分析与晶体塑性框架相结合的晶粒破碎建模方法。所提出的模型研究了经受严重塑性变形 (SPD) 过程的 FCC 金属的微观结构特征。该模型考虑了变形过程的几个方面，包括纹理演化、统计存储位错 (SSD) 和几何必要位错 (GND) 密度演化、晶粒破碎及其对整体机械响应的影响。所提出的模型应用于参考体积元素 (RVE)，其中颗粒分布并分配了初始位置。在模型中，每个颗粒都有能力分裂成 1024 个新的更小的颗粒，这随后导致应变硬化和晶粒细化。后者通过考虑晶粒-晶粒相互作用进行建模，为此将 GND 的概念纳入位错的平均自由程。假设 GND 是由晶界引起的，晶界限制了晶粒的自由变形并导致应力增加，从而导致晶粒尺寸减小。我们的谷物破碎假说是基于 Toth 等人的。(2010) 晶格曲率假设 [Toth, LS, Estrin, Y., Lapovok, R., Gu, C., 2010. 基于晶格曲率的晶粒破碎模型。学报。58, 1782–1794]。当超过亚晶粒之间的错误取向阈值时触发晶粒细化程序。使用纯铜材料的扭转试验校准模型参数。