Multiphase Solidification Modeling of Solidification Structure Evolution and Macrosegregation of Round Bloom Continuous Casting Process with Mold Electromagnetic Stirring and Final Electromagnetic Stirring

Based on Eulerian–Eulerian method, a 3D/2D multiphase solidification model, which takes into consideration the heat transfer and fluid flow with grains nucleation and crystal growth, is developed to predict the macrostructure evolution and macrosegregation in continuously cast round bloom. The results show that the mold electromagnetic stirring (M‐EMS) can accelerate superheat dissipation and promote grain nucleation, but the horizontal swirl induced by M‐EMS has a strong washing effect on the solidification front and leads to subsurface negative segregation. When the M‐EMS current intensity increases from 200 to 300 A, the subsurface negative segregation ratio decreases from 0.935 to 0.875. The final electromagnetic stirring (F‐EMS) not only improves the center segregation, but also leads to the formation of negative segregation zone near the round bloom center due to the enhancement of solute washing induced by F‐EMS. As the F‐EMS current intensity increases from 150 to 300 A, the center segregation ratio decreases from 1.148 to 1.075, and the negative segregation ratio near the strand center decreases from 0.985 to 0.977. Another phenomenon is found that the nucleation of equiaxed grain ahead of columnar tips restrains the solute diffusion and leads to a local macrosegregation in columnar‐to‐equiaxed transition zone.