Numerical analysis of arc plasma and weld pool formation by a tandem TIG arc

Multi-electrode welding processes are used in various industrial fields for higher productivity. These processes can use many combinations of welding methods, current values and polarities, and electrode alignments. However, this complicates welding phenomena. In this research, we focused on the tandem tungsten inert gas (TIG) arc, which is a relatively simple multi-electrode welding process. We performed a numerical investigation into the tandem TIG arc plasma and weld pool formation to clarify the phenomena involved. The weld spot of a tandem TIG weld is ellipsoidal in appearance and is deeper than that of a single-electrode TIG weld. Reduction in the shear stress of the plasma flow in the tandem TIG weld leads to a deeper penetration. Furthermore, the influence of the electrode alignment is calculated, and it is determined that the weld spot appearance significantly changes. The appearance is strongly related to the arc plasma shape. These numerical results show good agreement with the experimental results, which proves that our model has relatively high reliability.