Plasma arc and weld pool coupled modeling of transport phenomena in keyhole welding
Plasma arc and weld pool coupled modeling of transport phenomena in keyhole welding
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DOI：
10.1016/j.ijheatmasstransfer.2015.09.016
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发表时间：
2016
影响因子：
5.2
通讯作者：
Yan Li;Yanhui Feng;Yafei Li;Xinxin Zhang;Chuansong Wu
中科院分区：
文献类型：
--
作者：
Yan Li;Yanhui Feng;Yafei Li;Xinxin Zhang;Chuansong Wu
等离子弧焊涉及复杂的热、电、磁和流体动力学现象。迄今为止，人们分别对熔池和热等离子体电弧进行了大量的研究。然而，很少有研究将这两方面结合起来，更不用说将钥匙孔效应结合起来了。因此，为了进一步了解等离子体电弧锁孔焊接过程中的输运现象，建立了等离子体电弧与焊缝熔池耦合的统一模型，从而更全面地了解热等离子体过程中的能量转换和考虑锁孔效应的焊缝熔池传热。通过求解一系列包含质量、动量和热电磁能的控制方程，得到了电弧区域和熔池内的温度场和速度场。结果表明，约有10%的等离子弧从锁孔出口流出。在焊接过程中，热传导通量是电子冷凝通量的两倍以上。马兰戈尼剪切力明显优先于电磁力，熔池内出现两种环形流动。此外，还预测了电弧流、电势、电流密度和电磁力，以进一步了解热等离子体过程。在锁眼内发现了两个速度过渡点，弧从这里开始向外和向上流动，最后从金属表面流出。最后，对不锈钢板进行了实验，实测熔池与模型计算结果接近。
Plasma arc welding involves intricate thermal, electrical, magnetic and fluid dynamics phenomena. To date, tremendous research has been carried out on the weld pool or the thermal plasma arc separately. Yet few studies have integrated the both aspects, much less the keyhole effect in addition. Accordingly, as an endeavor to advance the understanding of the transport phenomena in keyhole welding with plasma arc, a unified model coupling plasma arc and weld pool has been developed to help gain access to the more complete knowledge of energy conversion in the thermal plasma process and heat transfer to the weld pool with the consideration of keyhole effect. By solving a series of governing equations that contain the mass, the momentum and the combined thermal, electric and magnetic energy, both temperature and velocity fields in the arc region and in the weld pool were exhibited. Results show that about 10% of plasma arc outflows from the keyhole exit. The heat conduction flux is more than two times of the electron condensation flux in the welding process. It is also found that the Marangoni shear takes obvious priority over the electromagnetic force, and two circular flows appear in the weld pool. Moreover, arc flows, electrical potential, current density and electromagnetic force were all predicted to further the understanding of thermal plasma process. Two velocity-transition points were found within the keyhole, from which the arc begins to flow outwards and upwards and finally outflows through the top metal surface. Finally, experiment was conducted on the stainless steel plate, and the measured weld pool is close to that calculated by our model.