Micro-Segregation Behavior of Solute Elements in the Mushy Zone of Continuous Casting Wide-Thick Slab

Based on the assumption that the transverse cross‐section of dendrites is a regular hexagon, a coupled macro‐heat transfer and solute diffusion model was developed to describe micro‐segregation behavior of solute elements in the mushy zone during wide‐thick slab continuous casting. The heat transfer model and the micro‐segregation model were validated by the industrial tests and the experiment measurements in literatures, respectively. The results show that the cooling rate decreases from 51.1°C s−1 at the surface to 0.13°C s−1 at the center of the wide‐thick slab of peritectic steel continuous casting. The effective cooling rate equaling to 1.78°C s−1 mainly depends on mold cooling and varies little with casting speed. The micro‐segregation behavior of solute elements in the mushy zone depends on back diffusion ability and local equilibrium at interfaces. Compared with other elements in the steel, phosphorus, and sulfur elements exhibit a much higher segregation ratio at the end of the solidification and are more significantly affected by the initial carbon content. Through the combination with the macro‐heat transfer model, the micro‐segregation model is introduced to investigate solidification characteristics of the peritectic steel and segregation behaviors of solute elements in the mushy zone during wide‐thick slab continuous casting. The segregation behavior is mainly determined by the diffusion and local equilibrium properties and affected by the solidification process.