Influence of casting parameters on level fluctuations and its industrial application

Abstract

The level fluctuations behavior of the molten steel in the steel slab continuous casting mold is the result of the combined effect of the molten steel flow in the mold, the mold itself vibration, and the fluctuation of the molten steel in the slab when rollers squeeze the slab. The stability of level fluctuations of the mold has a great effect on the behavior of slag entrainment in the continuous casting slab process. In industrial practice of steel slab continuous casting, the level fluctuations is detected in a certain zone of the top surface (such as the middle of the mold width direction) using a radioactive source or an eddy current sensor to represent the overall level fluctuations. In the current study, the effects of casting parameters on the top surface level profile of the mold were studied through the three-dimensional numerical simulation of the gas-liquid two-phase flow. The casting parameters include casting speed, argon flow rate, out-port angle of submerged entry nozzle(SEN)and mold width. The results show that the fluctuation amplitude at different positions of the top surface of the mold was different, and it changed with the variation of casting parameters. With the increasing of the casting speed and argon flow rate, the difference between the peak and the trough of the top surface level profile increased near the narrow face and the SEN, respectively. When the out-port angle of SEN was 15°, the surface level was higher near the SEN and the narrow face. When the out-port angle of SEN was 45°, large surface level was only observed near the SEN. The results show that it was necessary to arrange the level detection equipment near the SEN and the narrow face for mold level detection when using the conventional SEN with 15° out-port angle and the mold width was larger than 800 mm, ensuring more fully reflected the real behavior of level fluctuations of the mold, which can enhance the guidance of the surface quality of the rolled coils and effectively improve the control level of the continuous casting process. When using the SEN with 45° out-port angle, the arrangement of the original level detection remained unchanged.