Numerical simulation of the temperature field, weld profile, and weld pool dynamics in laser welding of aluminium alloy

A transient 3-d thermo-fluid model is developed to simulate the heat transfer and weld pool dynamics during the deep penetration laser welding of aluminium alloy AA2024. Numerical modelling and non-dimensional analyses are carried out to investigate the effect of driving forces on melt pool dynamics and geometry. The temperature-driven surface tension and its influence on weld pool geometry is analysed quantitatively by varying the input parameters. The normalised dimensions of the weld pool are plotted against dimensionless numbers viz. Peclet, Reynolds, Marangoni numbers to understand the uncertainty and changes in the process. The melt flow in weld pool is found to be laminar for the considered combination of material and process parameters. The conclusions derived in this work could explain the Marangoni convection in materials with a negative gradient of surface tension and provide an insight into the defects formation and their reduction in laser welding of aluminium alloys. The developed model is validated with experimental data and found in good agreement.