An interpolation-based transient solidification conditions model for numerical calculation of grain growth during laser welding

The weld microstructure is highly related to the performance of welded joints during the laser welding. The temperature gradient and pulling velocity are critical solidification conditions which play a major role in determining the grain evolution in the weld formation. Therefore, an interpolation-based transient solidification conditions model is proposed in this paper for numerical calculation of the grain growth during laser welding. The transient temperature gradient obtained in the model is compared with that from the previous method and the accuracy of transient temperature gradient is improved. The corresponding phase field (PF) model based on the obtained transient solidification conditions is developed to calculate the evolution process of grain growth. It is found that the morphology and spacing of the primary dendrite arm from the numerical calculation agree well with the experimental results. In the competitive growth stage, some grains are suppressed, which provides more space for neighboring grains to grow coarser. The solute redistribution and insufficient solute diffusion demonstrate significant effects on the solute concentration distribution. The proposed method is of great importance for controlling microstructure and improving the laser welding quality.