Abstract In the quest for the transport mechanism in the molten pool during hybrid laser-MIG welding of aluminum alloy, an improved three-dimensional numerical model is developed. A modified model for laser heat source is utilized to investigate the energy absorption mechanism in keyhole. Some driving forces are considered to simulate the fluid flow, such as electromagnetic force, surface tension and buoyancy. The effects of arc pressure and droplet impact are taken into account to track the free surface. Several dimensionless numbers are utilized to analyze the relative importance of driving forces. The temperature field, liquid velocity field and magnesium and zinc distribution are numerically and experimentally studied. Results shows that the laser beam create a great impression on the heat transfer, fluid flow, solute distribution and weld bead geometry. In MIG welding, there is an insufficient mixing zone at the front of the pool, while the solute distribution in hybrid laser-MIG welding is observed more uniform. Magnesium and zinc are found concentrated in lower and upper part of the molten pool, respectively. The mathematical model is well validated by the experimental observations, and the calculated element distribution agrees well with the experimental measurements. Furthermore, the improved model provides an effective method for parametric optimization to improve the properties of hybrid laser-MIG welding joints.

中文翻译：

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激光-MIG混合焊传热及溶质分布的数值研究

摘要 为探究铝合金复合激光-MIG焊接过程中熔池中的输运机制，建立了改进的三维数值模型。利用改进的激光热源模型研究了小孔中的能量吸收机制。考虑了一些驱动力来模拟流体流动，例如电磁力、表面张力和浮力。考虑电弧压力和液滴冲击的影响来跟踪自由表面。几个无量纲数被用来分析驱动力的相对重要性。数值和实验研究了温度场、液体速度场和镁和锌的分布。结果表明，激光束对传热、流体流动、溶质分布和焊道几何形状。在 MIG 焊接中，熔池前部存在不充分的混合区，而在混合激光 MIG 焊接中观察到的溶质分布更均匀。发现镁和锌分别集中在熔池的下部和上部。数学模型通过实验观察得到了很好的验证，计算出的元素分布与实验测量结果吻合良好。此外，改进的模型为参数优化提供了一种有效的方法，以改善混合激光 MIG 焊接接头的性能。发现镁和锌分别集中在熔池的下部和上部。数学模型通过实验观察得到了很好的验证，计算出的元素分布与实验测量结果吻合良好。此外，改进的模型为参数优化提供了一种有效的方法，以改善混合激光 MIG 焊接接头的性能。镁和锌分别集中在熔池的下部和上部。数学模型通过实验观察得到了很好的验证，计算出的元素分布与实验测量结果吻合良好。此外，改进的模型为参数优化提供了一种有效的方法，以改善混合激光 MIG 焊接接头的性能。