Study of Molten Pool Behaviour in Laser Welded 2205 Duplex Stainless Steel Using Different Numerical Models
A. Ghosh, P. Kalvettukaran, D. Misra and S.K. Acharyya
Understanding the flow characteristics within the molten pool and the creation of the weld shape holds significant theoretical and engineering importance. Numerical simulation is the best method for understanding the flow behaviour in the molten pool due to its greater flexibility and cost competitiveness, which enable efficient exploration of such intricate phenomena. The dimensions of the geometry are generally crucial in determining the flow pattern in the molten pool. Marangoni convection may occur in thin plates due to changes in surface tension, while thicker plates may experience buoyancy forces from natural convection. It would be intriguing to understand the flow pattern when thin plates are treated with a smaller laser beam diameter. Three numerical models have been created in the present paper using COMSOL Multiphysics to analyse the flow characteristics within the molten pool. The first model assumes laminar flow in the molten pool, while the other two models assume turbulent flow (yPlus and k-ω model). The models incorporate a pulsed heat source that is simulated using COMSOL’s events interface, which adjusts the time steps depending on the speed of the solution changes. The three models consider the temperature dependent thermo-physical properties, track the solid-liquid phase interface with keyhole, account for Marangoni convection and buoyancy forces. The melt pool shapes calculated by the models are compared with experimental results and found to be comparable. The intensity of the flow in the molten pool is determined by using dimensionless numbers like the Marangoni number and the ratio of the Marangoni number to the Grashof number.
Keywords: Nd:YAG laser, 2205 duplex stainless steel, laser beam welding (LBW), molten pool, weld bead, keyhole, numerical modelling, Marangoni number, Grashof number, Reynolds number