S. J. Na, W. I. Cho, J. H. Cho, KAIST, Daejeon, South Korea
A computational analysis of a molten pool in laser-GMA hybrid welding is achieved including free surface tracking using the well-known volume of fluid (VOF) method. Suggested three-dimensional transient numerical model includes all the known analytical key features of arc welding including the electromagnetic force, buoyancy, and arc pressure. In addition to the basic autogenous arc welding model, molten droplets are generated and allowed to fall down onto the pool to cover the gas metal arc welding process. A keyhole dynamics model is added to the GMAW simulation model with the assumption that the interaction between the laser beam and arc plasma is negligible. The keyhole model is based on some unique phenomena that include the multiple reflections, Fresnel absorption model and the recoil pressure in laser welding. The result shows the flow patterns of the molten pool in GMA-laser hybrid welding, which are then compared to the previously reported observation results. It could be revealed that in the early stage of welding process the molten flow at the bottom of the keyhole rises up slowly, and therefore a vortex is observed throughout the molten pool. However, the flow pattern becomes increasingly complicated as the hybrid welding progresses. The flow of the keyhole root is split into three main streams, while one stream is continuously maintained in the vortex. The developed simulation model can be further applied for analyzing the pore generation in deep keyholes and/or the movement and distribution of alloying elements in weld pool.
Summary: A computational analysis of a molten pool in laser-GMA hybrid welding is achieved including free surface tracking using the well-known volume of fluid (VOF) method. In addition to the basic GTAW model, molten droplets are allowed to fall down onto the pool to cover the gas metal arc welding process. A keyhole dynamics model is added to the GMAW model with the assumption that the interaction between the laser beam and arc plasma is negligible.
