About the influence of a steady magnetic field on weld pool dynamics in partial penetration high power laser beam welding of thick aluminium parts
About the influence of a steady magnetic field on weld pool dynamics in partial penetration high power laser beam welding of thick aluminium parts
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DOI：
10.1016/j.ijheatmasstransfer.2013.01.015
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发表时间：
2013-05-01
影响因子：
5.2
通讯作者：
Rethmeier, Michael
中科院分区：
文献类型：
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作者：
Bachmann, Marcel;Avilov, Vjaceslav;Rethmeier, Michael
开发了多物理场数值模型，用于研究在平焊铝的部分熔透高功率激光束焊接过程中垂直于焊接方向的稳定磁场的影响。使用有限元微分方程求解器 COMSOL Multiphysics 4.2 成功求解了三维传热、流体动力学（包括相变）和电磁场偏微分方程。所实现的材料模型使用直至蒸发温度的温度相关属性。考虑了熔池表面区域的马兰戈尼对流、重力场引起的自然对流和固液相变潜热。通过多孔介质形态的 Carman-Kozeny 方程对凝固进行建模。液态金属中诱导的洛伦兹力分布显着改变了熔体中的流动模式以及焊道的几何形状。结果表明，将稳定磁场应用于激光束焊接，相应的哈特曼数 Ha(2) 接近 10(4)，可以抑制由热毛细管流动引起的焊接横截面的特征酒杯形状。数值结果与使用 16 kW 盘形激光器焊接 AlMg3 获得的实验结果非常吻合。稳定的磁场由安装在焊接样本两侧的永磁体提供。最大磁通密度约为500 mT。结果表明，所施加的磁场对熔池动力学具有主要的耗散效应，与其极性无关。 (C) 2013 Elsevier Ltd. 保留所有权利。
A multi-physics numerical model was developed to investigate the influence of a steady magnetic field aligned perpendicular to the welding direction during partial penetration high power laser beam welding of aluminium in downhand position. Three-dimensional heat transfer, fluid dynamics including phase transition and electromagnetic field partial differential equations were successfully solved with the finite element differential equation solver COMSOL Multiphysics 4.2. The implemented material model used temperature-dependent properties up to evaporation temperature. Marangoni convection in the surface region of the weld pool, natural convection due to the gravitational field and latent heat of solid-liquid phase transition were taken into account. Solidification was modelled by the Carman-Kozeny equation for porous media morphology. The flow pattern in the melt as well as the weld bead geometry were significantly changed by the induced Lorentz force distribution in the liquid metal. It reveals that the application of a steady magnetic field to laser beam welding with corresponding Hartmann numbers Ha(2) approximate to 10(4) allows for a suppression of the characteristic wineglass-shape of the weld cross section caused by thermocapillary flow. The numerical results are in good agreement with experimental results obtained with welding of AlMg3 with a 16 kW disc laser. The steady magnetic field was delivered by permanent magnets mounted on both lateral sides of the weld specimen. The maximum magnetic flux density was around 500 mT. It shows, that the applied magnetic field has a predominant dissipating effect on the weld pool dynamics independently of its polarity. (C) 2013 Elsevier Ltd. All rights reserved.