Numerical simulation of weld pool formation in submerged arc welding process

Abstract

Submerged arc welding process which is applied to large constructions is a high heat input and high deposition rate process. To achieve a higher productive and higher quality process, the phenomena in the process have to be understood and controlled. However, the molten metal and the molten slag are covered by a flux during the process, and cannot be observed directly. In this study, a numerical simulation model of the weld pool formation in the submerged arc welding process is constructed to visualize the phenomena. In this model, both the molten metal and molten slag behavior are calculated and the vaporization of the molten slag is considered. The properties of the arc plasma which is a heat source of the process is given by a simplified heat source model in the simulation model. Radiative energy into the flux and pressure to keep an arc cavity are considered as heat source properties for SAW process simulation. The simulation model can reproduce the shape of the penetration and solidified slag covered the bead of the experimental result by adjusting the heat source parameters. Moreover, influence of the flux on the penetration formation is discussed by the model. When the flux exists, the bead width is wider and the bead height is lower than those without flux. This is because, the temperature of the side region of the bead becomes higher before the heat source passes, because the energy given into the flux is transported to the base metal when the flux exists.