Macro-micro modeling and simulation on columnar grains growth in the laser welding pool of aluminum alloy

The heat transfer and columnar grains growth in the laser welding pool of 2A14 aluminum alloy under different welding parameters are investigated through macro-micro modeling and simulation. A macroscopic heat transfer model is proposed to calculate the temperature field in the laser welding pool under different welding parameters. Computed fusion profiles agree well with experimental measurements. The equations of transient pulling velocity, temperature gradient and columnar grains growth orientation during solidification of the laser welding pool are developed. A phase field model coupled with transient pulling velocity, temperature gradient, columnar grains growth orientation and the flow field is developed to simulate columnar grains growth in the laser welding pool under different welding parameters. Laser welding experiments are also carried out to observe columnar grains growth in the laser welding pool under different welding parameters. Simulated columnar grains morphology, spacing and growth orientation give a good agreement with experimental measurements. Competitive growth of columnar grains with different growth orientations is also predicted by the phase field model. Predicted competitive growth process is in accordance with experimental findings.