Numerical modeling of the temperature distribution and melt flow in dissimilar fiber laser welding of duplex stainless steel 2205 and low alloy steel

The research outlined in this paper pertains to the computational modeling and experimental investigation of laser keyhole welding between duplex stainless steel 2205 and low carbon steel (A516). A crucial aspect of keyhole welding entails predicting the phase transition behavior of the materials involved. The vaporized metal generates a recoil pressure and distorts the interface between the liquid and vapor phases, thus forming a vapor capillary. A multiphysics model employing the finite volume method was proposed to achieve a highly accurate simulation of the temperature and velocity fields. The findings demonstrate that the resulting weld bead relies heavily on the keyhole's structural characteristics. Additionally, analysis of the temperature distribution at a specific temporal and spatial point reveals that duplex stainless steel exhibits elevated temperatures owing to low thermal penetration at a distance of 5 mm from the juncture of the two components compared to A516. The numerical simulation results were in good agreement with experimental results for prediction of temperature filed and melt flow that have impact on weld bead and melt pool geometry. The weld bead width changes according to variation of welding speed and laser power has been in good agreement with the temperature distribution at upper surface of the workpiece extracted from simulation results. The melt pool geometry predicted from the simulation results (melt flow and temperature field) has been in good agreement with the melt pool geometry of the experiment. The temperature distribution from simulation results has a good correlation with the microstructural changes of the melt pool region according to the melting, solidification and temperature gradient at the melt pool region and adjacent HAZ of base metals.