Thermoelectric magnetohydrodynamic control of melt pool dynamics and microstructure evolution in additive manufacturing
Thermoelectric magnetohydrodynamic control of melt pool dynamics and microstructure evolution in additive manufacturing
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DOI：
10.1098/rsta.2019.0249
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发表时间：
2020-04
期刊：
影响因子：
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通讯作者：
A. Kao;T. Gan;C. Tonry;I. Krastiņš;I. Krastiņš;K. Pericleous
中科院分区：
文献类型：
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作者：
A. Kao;T. Gan;C. Tonry;I. Krastiņš;I. Krastiņš;K. Pericleous
在金属增材制造中，由于快速加热和随后的快速冷却，熔池中的大的热梯度产生大的热电流。将外部磁场应用于该过程通过热电磁流体动力学引入流体流动。对流传输的热量和质量，然后可以修改熔池动力学和改变微观结构的演变。作为一种新技术，这在控制过程以提高质量和减少缺陷形成方面显示出巨大的前景。然而，科学界对这种物理现象的基本原理知之甚少，无法支持实际实施。为了解决这一耦合熔化/凝固、电磁学、流体力学、热和质量传输等关键现象的多物理问题，将流体动力学的格子玻尔兹曼方法与解决凝固建模和电磁学的专用代码相结合。这里提出的理论研究调查的流体动力学机制所引入的磁场。修改后的熔池形状和热场的稳态解，然后使用基于元胞自动机的晶粒生长模型来预测微观结构的演变。结果清楚地表明，流体动力学机制，因此，微观结构特征是强烈依赖于磁场方向。这篇文章是“软物质和生物物质中的模式”主题的一部分。
Large thermal gradients in the melt pool from rapid heating followed by rapid cooling in metal additive manufacturing generate large thermoelectric currents. Applying an external magnetic field to the process introduces fluid flow through thermoelectric magnetohydrodynamics. Convective transport of heat and mass can then modify the melt pool dynamics and alter microstructural evolution. As a novel technique, this shows great promise in controlling the process to improve quality and mitigate defect formation. However, there is very little knowledge within the scientific community on the fundamental principles of this physical phenomenon to support practical implementation. To address this multi-physics problem that couples the key phenomena of melting/solidification, electromagnetism, hydrodynamics, heat and mass transport, the lattice Boltzmann method for fluid dynamics was combined with a purpose-built code addressing solidification modelling and electromagnetics. The theoretical study presented here investigates the hydrodynamic mechanisms introduced by the magnetic field. The resulting steady-state solutions of modified melt pool shapes and thermal fields are then used to predict the microstructure evolution using a cellular automata-based grain growth model. The results clearly demonstrate that the hydrodynamic mechanisms and, therefore, microstructure characteristics are strongly dependent on magnetic field orientation. This article is part of the theme issue ‘Patterns in soft and biological matters'.