Fluctuation of steel–slag interface in flexible thin slab casting mold
摘要
In order to examine the flow state of the steel–slag interface in a thin slab mold at high casting speed, a flexible thin slab casting mold and a novel five-hole nozzle were investigated. The maximum velocity and fluctuation height of the steel–slag interface in the mold served as the evaluation criteria. Numerical simulation techniques, including large eddy simulation and volume of fluid, were employed to develop a two-phase flow model of liquid steel and slag. This model facilitated the analysis of the fluctuation behavior of the steel–slag interface and the mechanisms of slag entrapment. The results indicated that maintaining the stability of the steel–slag interface could be achieved by ensuring that the maximum velocity did not exceed 0.30 m s−1 or that the wave height remained below 30 mm. The relationship between the maximum velocity and wave height of the steel–slag interface was established by analyzing different casting speeds. Slag entrapment occurred when the maximum velocity exceeded the critical value. The critical velocity for shear slag entrapment was 0.485 m s−1, while for vortex slag entrapment, it was when the velocity of the swirl center reached 0.235 m s−1. Electromagnetic braking proved effective in controlling flow in the mold, reducing fluctuations in the steel–slag interface, preventing slag entrapment, and maintaining the position of the interface. Furthermore, it facilitated the control of the uniformity and stability of slag movement along the outer wall of the submerged entry nozzle and the copper wall of the mold.