Transient Simulation of Mold Heat Transfer and Solidification Phenomena of Continuous Casting of Steel

A comprehensive model of heat transfer and solidification phenomena has been developed including microstructure evolution and fluctuation macrosegregation in continuously cast steel slabs with an objective of evaluation of various mold cooling conditions. The study contains plant trials, metallographic examinations, and formulation of mathematical modeling. The plant trials involved sample collection from three slab casters in use at two different steel plants. The metallographic study combined measurements of dendrite arm spacings and macrosegregation analysis of collected samples. A one-dimensional mathematical model has been developed to characterize the thermal, solidification phases, microstructure evolution, interdendritic strain, and therefore, the macrosegregation distributions. Two cooling approaches were proposed in this study to evaluate the Newtonian heat transfer coefficient in various mold regions. The first approach is a direct estimation approach (DEA), whereas the second one is a coupled approach of the interfacial resistor model and direct estimation approach (CIR/DEA). The model predictions and standard analytical models as well as the previous measurements were compared to verify and to calibrate the model where good agreements were obtained. The comparison between the model predictions and the measurements of dendrite arm spacings and fluctuated carbon concentration profiles were performed to determine the model accuracy level with different cooling approaches. Good agreements were obtained by different accuracy levels with different cooling approaches. The model predictions of thermal parameters and isotherms were analyzed and discussed.