Simulation of Microstructure Evolution During Solidification Process in Laser Welded Molten Pool of Al-Cu Alloy Under Forced Flow

In this work,a cellular automaton-finite difference-lattice Boltzmann(CA-FD-LB)coupled model was developed to simulate dendrite evolution during the whole solidification process of the Al-Cu alloy welding pool. The first and second vortices’locations in the lid driven flow were simulated. And the results show a high agreement with the results that have been published in the literature. The quantitative relationship between the growth rate of dendritic tip and the undercooling under isothermal pure diffusion circumstances exhibits outstanding agreement with the predictions of the Lipton Glicksman Kurz (LGK)model. In the presence of external flow,the growth morphology of dendrites demonstrates asymmetry because the solute diffusion layer at the upstream tip of the dendrites becomes narrower under the effect of squeezing of flow,resulting in a larger concentration gradient that promotes growth. Conversely,the downstream region exhibits the opposite behavior. Additionally,flow enhances the solidification process,leading to a shorter solidification time. The results of simulation and experiment are 117 μm and 91 μm respectively,and the relative error is about 28. 6%,showing the reliability of the coupled model. © 2024 Cailiao Daobaoshe/ Materials Review. All rights reserved.