Abstract

The main attraction of cellular automaton (CA) method used in computational material science lies on not only the simulation of recrystallization without the complicated differential equations calculation, but also the visualization of nucleation and grain growth during discontinuous recrystallization. In this work, by incorporating the idea of multilevel cellular space into the classical CA simulation framework and formulating cellular state transformation rules and data transfer rules between different levels of cellular space, the multilevel cellular automaton (MCA) model for dynamic recrystallization (DRX) is constructed for the first time. The developed MCA model includes a multilevel recrystallized nucleation (MRN) module and a full-field multilevel grain topological deformation (FMGTD) module. The thermal compression experiments of 316LN stainless steel are carried out, and the developed MCA model is applied to the numerical simulation of DRX for 316LN steel. The accuracy and reliability of this model are verified by comparing simulation results with experimental results. The influences of simulation parameters such as the number of levels N in the FMGTD module and the discrete strain increment on simulation results are discussed. The discrete cellular space area (i.e., grain topology mapping accuracy) in the MCA model increases with N but decreases with the discrete strain increment. The results show that the developed MCA model can not only describe the grain topological deformation in the DRX process more accurately but also more compatible with the physical mechanism of recrystallized nucleation. The calculation accuracy of the MCA model is higher than the existing CA model. Besides, the MCA model can be closer to the real deformation process while ensuring the high grain topology mapping accuracy and solve the problem of the loss of grain boundary area in the existing CA model.

中文翻译：

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动态再结晶的中尺度模型：多级细胞自动机模拟框架

摘要

计算材料科学中使用的元胞自动机（CA）方法的主要吸引力不仅在于无需复杂的微分方程计算的再结晶模拟，还在于不连续再结晶过程中成核和晶粒长大的可视化。在这项工作中，通过将多层细胞空间的思想纳入经典的CA模拟框架中，并制定细胞状态转换规则和不同层细胞空间之间的数据传输规则，用于动态重结晶（DRX）的多层细胞自动机（MCA）模型成为首次构建。开发的MCA模型包括一个多级重结晶成核（MRN）模块和一个全场多级晶粒拓扑变形（FMGTD）模块。进行了316LN不锈钢的热压缩实验，并将开发的MCA模型应用于316LN钢DRX的数值模拟。通过将仿真结果与实验结果进行比较，验证了该模型的准确性和可靠性。仿真参数的影响，例如级别数讨论了FMGTD模块中的N和离散应变增量对仿真结果的影响。MCA模型中的离散单元空间区域（即晶粒拓扑映射精度）随N的增加而增加，但随离散应变的增加而减小。结果表明，建立的MCA模型不仅可以更准确地描述DRX过程中晶粒的形变，而且与重结晶形核的物理机理更加兼容。MCA模型的计算精度高于现有的CA模型。此外，MCA模型可以在保证较高的晶粒拓扑映射精度的同时，更接近真实的变形过程，解决了现有CA模型中晶粒边界面积损失的问题。