Heat transfer and fluid flow in fusion type PA-GTA double-sided welding

In comparison with conventional single-sided arc welding, double-sided arc welding powered by a single power supply has remarkable advantages in enhancing penetration, minimizing distortion and improving welding production. In this paper, a three-dimensional steady numerical model is developed for the heat transfer and fluid flow in a fusion type plasma arc (PA)-gas tungsten arc (GTA) double-sided welding process. Based on the numerical model, the distributions of the fluid flow and temperature field are calculated. Numerical results show that the peak temperature and temperature gradient in the weld pool in the PA side are higher than the values in the GTA side. Within the weld pool, the electromagnetic force drives the melted metal to move from two sides to the central part of the weld pool, and this effect is positive to penetrating the workpiece. The fluid flow of the melted metal in the free surface of the weld pool is fiercer than the flow within the weld pool, and the biggest flow velocity of the melted metal occurs in the free surface in the PA side. A comparison of the cross section of the weld bead with the experimental result shows that the numerical model's accuracy is reasonable.