Numerical and experimental studies on the effects of molten steel viscosity on fluid flow, inclusion motion, and temperature distribution in a tundish

Abstract

Tundishes are refractory vessels that are used to control the flow of molten steel, promote the removal of inclusions, and increase the homogeneity of temperature and composition during continuous casting processes by optimizing their geometric shape. The flow of molten steel in tundishes is a high-temperature process, and the optimization of the tundish structure is carried out by numerical and physical simulations. In numerical simulations, the viscosity of molten steel is generally set to a constant value; however, in industrial scenarios, the molten steel viscosity is variable with temperature. In the present work, the effects of molten steel viscosity varying with temperature on fluid flow, inclusion motion, and temperature distribution in a tundish were investigated by numerical simulations based on the modification of the top heat flux of the tundish, and the results were further verified by an industrial experiment. The removal rate of inclusions obtained from the industrial experiment was 40.40%. In numerical simulations, the inclusion removal rates were 50.85% and 40.67% when the fluid viscosity was constant and variable, respectively. Hence, when the molten steel viscosity was variable, the numerical simulation result was closer to the experimental one. The industrial experiment revealed that the temperature difference between the edge flow and the middle flow on the tundish liquid surface was 0 K. In numerical simulations, when the top heat fluxes of the tundish were 15 000 and 100 W/m2, the temperature differences on the tundish liquid surface were 5.95 and 0.16 K, respectively.