Validation of Fluid Flow and Solidification Simulation of a Continuous Thin-Slab Caster

Abstract

Models of fluid flow and solidification in the mold region of a continuous thin-slab caster have been developed and validated with extensive experimental measurements on the AK Steel Mansfield stainless-steel caster. Three-dimensional turbulent flow of molten steel through the nozzle into the mold cavity is modeled with the finite difference code CFX 4.2, using the standard K-e turbulence model and a fixed, structured grid. The results agree with flow measurements in a full-scale water model of the process. Next, the corresponding steady heat conduction equation is solved to predict the distribution of superheat in the molten pool. The predicted temperatures in the molten steel compare well with measurements conducted by inserting a thermocouple probe downward through the top surface at several locations in the operating thin slab caster. Next, solidification of the steel shell is simulated using a transient heat conduction model that features a detailed treatment of the flux layers in the interfacial gap and incorporates the superheat flux calculated from the fluid flow model. This model was calibrated with temperature measurements obtained from thermocouples in the copper mold during operation. It was run under the transient conditions present during a breakout. The predicted shell thickness profiles are compared with many shell thickness profiles measured around the perimeter of a breakout shell. Of greatest interest is the uneven thinning of the shell near the narrow face where the steel jet impinges, which is different between steady-state and the transient conditions of the breakout. This work demonstrates the quantitative ability of this modeling approach to simulate coupled fluid flow and solidification heat conduction in a real steel continuous casting process.