针对双钨极TIG电弧热源, 在已建立的双钨极电弧-熔池统一的三维数学模型的基础上, 以SUS304不锈钢为母材, 模拟得到了双钨极TIG电弧和熔池的温度、速度、电流密度、磁通密度和电磁力等分布, 模拟结果与已有的实验结果吻合良好. 考虑了熔池所受浮力、电磁力、等离子流拉力和Marangoni剪切力以及湍流效应, 分析了熔池热输入的分布和熔池表面剪切力的变化, 并分别比较了这几个力单独作用下的熔池流动与传热, 同时结合无量纲数Pe, 比较了熔池热传导和热对流的相对强弱. 结果表明, 双钨极电弧的非轴对称特性导致熔池表面的电流密度、热流密度、等离子流拉力和Marangoni剪切力等出现非轴对称分布, 最终形成了熔池的非轴对称形貌, 而熔池的发展演化对电弧行为无明显影响. 与TIG电弧相比, 双钨极TIG电弧的等离子流拉力明显减小. Marangoni剪切力决定不锈钢熔池的流动状态, 且对流传热主导不锈钢熔池的热传递, 这两者的共同作用决定熔池的传热过程, 是形成不同熔池形貌的根本原因。

Based on a developed unified three dimension (3D) mathematical model including two tungsten electrodes arc and weld pool for double electrode TIG arc heat source, the temperature, velocity, current density, magnetic flux and Lorentz force of the double electrodes TIG arc and the weld pool are obtained for SUS304 stainless steel. The simulated results are in fair agreement with the experimental results available. Buoyance, Lorentz force, plasma drag force, Marangoni shear stress and turbulent effect are taken into account to formulate the weld pool behavior and the effects of the each force on the flow of the weld pool are studied respectively. The heat flux and shear stress at the weld pool surface are analyzed as well. A dimensionless number Pe is used to compare the relative importance of convective heat and conductive heat in the weld pool. It is shown that non-axisymmetric double electrode arc results in the non-axisymmetric characteristics of the current density, heat flux, plasma drag force and Marangoni shear at the weld pool, and thus produces non-axisymmetric weld pool profiles. The evolution of the weld pool has little effect on the arc behavior. The plasma drag force of the double tungsten electrode TIG arc decreases significantly compared with that of the TIG arc. The Marangoni stress determines the weld pool flow and the heat convected dominates the heat transfer in the weld pool, their combination effect determines the heat transfer in the weld pool, which is the essential reason for the formation of the different weld pool profiles。