NUMERICAL SIMULATION OF MACRO-SEGREGATION IN STEEL INGOT DURING SOLIDIFICATION

摘要

A mathematical model coupling the momentum, energy and species conservation equations was proposed to calculate the macro-segregation of Fe-C alloy ingot during solidification. The corresponding simulation software which concurrently solves the macroscopic mass, momentum, energy and species conservation equations has been developed by applying the SIMPLE algorithm. The thermo-solutal convection in a NH_4Cl-H_2O ingot is verified and the result shows good agreement with that reported. Then macro-segregation in a steel ingot is simulated by using the developed program. The steel ingot is in a rectangular mold with a riser. The fluid flow is mainly induced by the temperature field and the solid fraction. The macro-segregation pattern is mainly affected by the thermo-induced convection in the mushy zone. The negative segregation forms along the walls of the casting. The positive segregation forms at the top center of the casting into the riser. The species concentration reaches the peak in the center of the ingot where solidification ends lastly.