Numerical Simulation of Macrosegregation in Water-Cooled Heavy Flat Ingot During Solidification

Based on a volume-averaged two-phase approach, a coupled concentration, temperature, and velocity fields model has been established to predict the formation of macrosegregation during solidification. Because of the significant influence of velocity field on solute transfer and distribution during solidification process, the density of liquid steel was set as a function of temperature and concentration to accurately calculate the velocity field. Therefore, the influence of gravity, temperature gradient, concentration gradient, and volume shrinkage on velocity field distribution was comprehensively considered. The calculation result showed good agreement with previous reports. Thereafter, the current model was applied to simulate the solidification of 12Cr2Mo1R (ASTM standard 2.25Cr1Mo) heavy ingot, and the influence of surface cooling intensity on the final carbon macrosegregation was investigated. The results showed that with the increase of cooling intensity, the solidification time, flow velocity, and mushy zone width decrease, and as a result, macrosegregation is alleviated. When the heat-transfer coefficient is less than 1000 W m−2 K−1, macrosegregation dramatically decreases with the rise of cooling intensity. In contrast, when heat-transfer coefficient is greater than 1000 W m−2 K−1, the effect of reducing the central carbon segregation by increasing cooling is weakened.