Columnar grain growth with shear flow in molten pool of Ni-Cr alloy was simulated with a coupled model of grain growth and solute transport.The results indicate that shear flow alters solute distribution at the vicinity of columnar grains.The solute concentration gradient on the upstream side is greater,while that on the downstream side is smaller,leading to asymmetrical growth of columnar grains.In the interior of a columnar grain,solute concentration increases from the bottom to the dendrite tip,but the rate of increase tends to be reduced.The simulated results are consistent with the experiments.
A coupled model of grain growth and solute transfer based on cellular automaton （ CA ） method was established and applied to grain growth simulation in molten pool of nickel-based alloy. The CA method was used to simulate welding solidification process successfully, but few researches had taken the effect of convection on dendrite morphology into account. In this paper, solute transfer model was used to calculate the effect of convection and diffusion on solute field with CA method simulating grain growth. The results indicate that convection has a significant effect on the morphology of equiaxed grain. Dendrite growth in the upstream direction is amplified, while it is inhibited in the downstream direction. With inlet velocity increasing, this effect becomes more severe.
