A numerical analysis of molten pool convection considering geometric parameters of cathode and anode
A numerical analysis of molten pool convection considering geometric parameters of cathode and anode
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作者：
S. Lee;S. Na
研究了气体保护气体保护静止气体保护钨极气体保护焊(GTAW)熔池内的传热和流体流动，重点研究了电极倾角、弧长和作用于熔池表面的电弧压力引起的表面凹陷等几何参数对焊接电弧的影响。考虑了熔池对流的驱动力，即自感电磁力、熔池表面温度梯度引起的表面张力和电弧等离子体流作用于熔池表面的剪应力。将该数值模型应用于硫磺含量为30ppm的304L不锈钢板材。随着焊接电流的增大，由于熔池表面有较强的流动，焊接中心熔深的计算值与实验值之间的偏差增大。随着电极斜角的减小，作用在熔池表面的剪应力增大。因此，融合宽度增加，融合深度减小。改变弧长对熔化形状没有影响，因为决定熔池表面流动的剪应力变化很小。从模拟结果看，考虑到熔池表面的凹陷，增加弧长和提高阳极温度的影响导致了更准确的熔宽。
The heat transfer and fluid flow in the molten pool during stationary gas tungsten arc welding (GTAW) using Ar shielding gas have been studied with an emphasis on the impact of geometric parameters on the welding arc, such as electrode bevel angle, arc length and surface depression due to arc pressure acting on the molten pool surface. Driving forces responsible for weld pool convection, i.e., self-induced electromagnetic force, surface tension due to the temperature gradient at the surface of the molten pool and shear stress acting on the molten pool surface by the arc plasma flow, were considered. The numerical model was applied to type 304L stainless steel plate with 30 ppm sulfur. As the welding current increased, the discrepancy of penetration at the weld center between the calculation and experiment increased because of the strong flow along the molten pool surface. As the electrode bevel angle decreased, the shear stress acting on the molten pool surface increased. Therefore, the fusion width increased and the fusion depth decreased. Changing the arc length did not influence the fusion shape because variation in shear stress, which determined the surface flow along the molten pool surface, was minor. From the simulation, considering the depression of the molten pool surface, the effects of the increased arc length and elevated anode temperature resulted in a more accurate fusion width.