Numerical simulation of fluid flow and temperature field in keyhole double-sided arc welding process on stainless steel

Double-sided are welding process powered by a single supply is a type of novel high-production process. In comparison with the conventional single-sided are welding, this process 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 plasma arc (PA)-gas tungsten are (GTA) double-sided keyhole welding process. The model considers the surface tension gradient, electromagnetic force and buoyancy force. A CCD camera is used to observe the size and shape of the keyhole and weld pool. The acquired images are analysed through image processing to obtain the surface diameters of the keyhole on the two sides. A double-V-shaped keyhole geometry is then proposed and its characteristic parameters are derived from the images and cross-section of weld bead. In the numerical model, the keyhole cavum within the weld pool is treated as a whole quality, whose temperature is fixed at the boiling point of the workpiece material. The heat exchange between the keyhole and weld pool is treated as an interior boundary of the workpiece. Based on the numerical model, the distributions of the fluid flow and temperature field are calculated. A comparison of cross-section of the weld bead with the experimental result shows that the numerical model's accuracy is reasonable.