Modeling of Cold Metal Transfer Spot Welding of AA6061-T6 Aluminum Alloy and Galvanized Mild Steel
Modeling of Cold Metal Transfer Spot Welding of AA6061-T6 Aluminum Alloy and Galvanized Mild Steel
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DOI：
10.1115/1.4027673
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发表时间：
2014-10
影响因子：
4
通讯作者：
Z. Rao;Jiangwei Liu;Pei-chung Wang;Yunxiao Li;S. Liao
中科院分区：
文献类型：
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作者：
Z. Rao;Jiangwei Liu;Pei-chung Wang;Yunxiao Li;S. Liao
建立了1 mm厚AA6061-T6铝合金与1 mm厚镀锌低碳钢(即AISI1009)冷金属转移(CMT)点焊过程的三维暂态统一模型。模拟了CMT工艺过程，包括电弧的产生和演变；电极的上下移动、熔滴形成和浸入熔池；熔池动力学；锌在电弧中的蒸发和锌蒸气扩散。研究了轧件间隙和钢表面蒸发锌蒸气对CMT工艺的影响。结果表明，CMT焊接过程中，电弧温度、速度和压力不断变化，这与焊接电流、弧长和锌挥发量的变化有关。研究发现，锌的蒸发导致极高的电弧压力和锌蒸气在钢表面附近的向上流动，这将导致电弧失稳，并为熔滴撞击提供阻力。两个工件之间的间隙的存在可以促进电弧等离子体的膨胀，导致较小的电弧压力和更强烈的锌蒸气从钢表面向上流动。实验中观察到的现象与模拟结果相吻合。
In this article, a three-dimensional (3D) transient unified model is developed to simulate the transport phenomena during the cold metal transfer (CMT) spot welding process of 1 mm thick aluminum AA6061-T6 and 1 mm thick galvanized mild steel (i.e., AISI 1009). The events of the CMT process are simulated, including arc generation and evolution; up-and-down movement of electrode, droplet formation and dipping into the weld pool; weld pool dynamics; zinc evaporation, and zinc vapor diffusion in the arc. The effects of the gap between the two workpieces and effects of zinc vapor evaporated from the steel surface on CMT process are studied. The results show that the arc temperature, velocity, and pressure keep changing during the CMT process, which is related to the variations of welding current, arc length, and zinc evaporation. It is found that the zinc evaporation leads to the extremely high arc pressure and the upward flow of zinc vapor near the steel surface, which would induce the arc instability and provide the drag force for the droplet impingement. The presence of the gap between the two workpieces can improve the expansion of the arc plasma, resulting in the smaller arc pressure and the more intensive upward flow of zinc vapor from the steel surface. The phenomena observed in the experiment are in agreement with the modeling results.