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

Abstract

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.

Phase Transition of Peritectic Steel Q345 and Its Effect on the Equilibrium Partition Coefficients of Solutes

“…As shown in the Figure 5f, ave_k S is the minimum, thereby indicating that S in steel Q345 exhibits an ultra-strong tendency toward segregation, which is consistent with Reference [4]. ave_k C is 0.2, which is slightly higher than that of S, is followed by P, with an ave_k P of 0.273.…”

“…This coefficient plays an important role in segregation problems during alloy solidification [2][3][4]. Generally, when the partition coefficient is high, the partitioning effect is weak, and consequently, a small segregation degree is obtained during solidification [1].…”

“…The equilibrium partition coefficient affects solute redistribution in the mushy zone and the segregation degree [4,14]. This coefficient is a critical parameter for segregation simulation and modeling accuracy [15,16].…”

Development of a CA-FVM Model with Weakened Mesh Anisotropy and Application to Fe–C Alloy

“…Additionally, Scheil's prediction is always higher than that by the CA-FVM model. C with the solid fraction, and the comparison with the prediction by Scheil [3] and Ueshima [44] models. Both Scheil and Ueshima models assume that the solute mixes uniformly in the liquid phase [3,44].…”

“…Both Scheil and Ueshima models assume that the solute mixes uniformly in the liquid phase [3,44]. Ueshima model [44] …”