Numerical Simulation Study on Quality Control of the Center Macroscopic Segregation in the Continuous Casting Slab

Based on the continuous mixing model, the two-dimensional flow-heat transfer model was established in this paper. The forming process of the central macroscopic segregation in the continuous casting slab and the influence of the reduction technology on the macroscopic segregation in the continuous casting slab were simulated in this paper. The formation mechanism of the central macroscopic segregation was revealed in the solidification process of the continuous casting slab. The results of the simulation showed that the central macroscopic segregation of the continuous casting slab was formed in the mushy zone. During the process of the solidification, there was different carbon solute solubility between the liquid phase and the solid phase, leading to the redistribution of the carbon solute between the liquid phase and the solid phase. A large amount of the carbon solute was rejected to the mushy zone from the solid phase. There was no dilution effect on the enrichment of the carbon solute in the mushy zone because of the decrease in the liquid fraction in this zone. The rate of the carbon solute diffusion got slowed down in the mushy zone and led to the enrichment of the carbon solute in mushy zone. With the solidification of the continuous casting slab, the central macroscopic segregation of the continuous casting slab was finally formed. At the same time, the numerical simulation of the quality control of macroscopic segregation by mechanical reduction in continuous casting slab was carried out in this paper. The mechanical reduction which influenced the central macroscopic segregation of the continuous casting slab was simulated by applying the vertical velocity to the casting direction of the slab at specific position of the continuous casting slab. Under this simulation condition, it was found that the central macroscopic segregation of the continuous casting slab could be effectively improved by 10mm of the reduction amount and at the reduction position with 0.4 of liquid fraction.