A fast and accurate mathematical model has been developed to simulate mixing in the tundish and the mold and accurately predict the composition profiles that develop in the solidified slabs and blooms. The model has been calibrated with 3-D model calculations and water model measurements and verified with measurements at several plants. It is being further refined to run on personal computers at the steel plants to allow efficient grade classification, minimizing both customer complaints and yield losses. The effect of casting variables are now being investigated with the model to optimize grade changes for any casting operation. Mold powder melts to form a protective flux layer on the top surface of the steel, which helps to trap impurities and inclusions.
Results indicate that the thickness of the beneficial liquid layer is highly nonuniform.
Detrimental solid inclusions caused by surface turbulence are most likely in the thinnest regions, whose locations have been successfully predicted by the model. Mold flow conditions, which are affected by the inlet nozzle geometry, are found to control this layer and are being investigated. Model of Inclusion Agglomeration and Removal Removing inclusions from the molten steel is important to prevent surface defects in the steel products. To clarify the mechanism of inclusion removal from molten steel, a model of inclusion collision is being developed to simulate the evolution of the inclusion size distribution. The model includes the Saffman model for inclusion collision in turbulent flow and Stokes law for inclusion migration.