Effect of flow control devices on grade change process in a five-strand Tundish

Abstract

A mathematical model was developed to investigate turbulent flows in steady-state casting and steel intermixing during grade change process in a five-strand tundish under different flow control devices (FCDs). The results showed that the baffle had significant influence on flow state of molten steel during steady-state casting, while the dam and turbulence inhibitor (TI) showed smaller effect. When the tundish was equipped with baffle, the mean residence time and the overall mean standard deviation of each strand decreased by nearly 100.3 s and 46%, the volume of the piston region and dead zone decreased by 13.5% and 6.4%, respectively, compared to without baffle. For grade change process, the baffle had great influence on the steel mixing, while the dam and TI showed less influence. The mass fraction of new grade reached 0.9 at 333 s near the third strand, and remained around 0.8 near the fifth strand at the later stage when the baffle was removed, which seriously deteriorated the steel mixing and the consistency among strands. The tundish equipped with baffle and square TI, but without dam, shows better performances both on flow consistency and new grade diffusion.