Predicting microstructure evolution for friction stir extrusion using a cellular automaton method
Predicting microstructure evolution for friction stir extrusion using a cellular automaton method
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DOI：
10.1088/1361-651x/ab044b
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发表时间：
2019-04-01
影响因子：
1.8
通讯作者：
Ding, Hongtao
中科院分区：
文献类型：
--
作者：
Behnagh, Reza Abdi;Samanta, Avik;Ding, Hongtao
摩擦搅拌挤压（FSE）提供了一种固相合成方法，将离散的金属碎片或粉末固结成块状材料形式。在这项研究中，一个FSE机床与中心孔被驱动在高转速到金属芯片包含在一个腔室，机械搅拌和巩固的工作材料。软化的固结材料通过工具的中心孔被挤出，在此期间，由于强烈的热机械载荷，材料的微观结构发生显著的转变。不连续动态再结晶被认为是镁合金FSE过程中组织演变的主要机制。在此过程中，复杂的热机械载荷驱动着微观结构的演变。利用商业软件DEFORM 11.0建立了一个三维有限元工艺模型，预测了FSE过程中的温度场、机械变形和材料流动。以模拟的热机械载荷为输入，建立了模拟材料晶粒微观组织动态演化的元胞自动机模型。预测的晶粒尺寸与实验测量的晶粒尺寸吻合良好。该数值研究为模拟摩擦搅拌过程的微观组织转变提供了有力的分析工具。
Friction stir extrusion (FSE) offers a solid-phase synthesis method consolidating discrete metal chips or powders into bulk material form. In this study, an FSE machine tool with a central hole is driven at high rotational speed into the metal chips contained in a chamber, mechanically stirs and consolidates the work material. The softened consolidated material is extruded through the center hole of the tool, during which material microstructure undergoes significant transformation due to the intensive thermomechanical loadings. Discontinuous dynamic recrystallization is found to have played as the primary mechanism for microstructure evolution of pure magnesium chips during the FSE process. The complex thermomechanical loading during the process drives the microstructure evolution. A three-dimensional finite element process model is developed using commercial software DEFORM 11.0 to predict the thermal field, mechanical deformation and material flow during the FSE process. Using the simulated thermomechanical loadings as input, a cellular automaton model is developed to simulate the dynamic evolution of the material grain microstructure. The predicted grain size is in good agreement with the experimentally measured grain size. This numerical study provides a powerful analysis tool to simulate the microstructure transformation for friction stir-based processes.