Effect of Casting Speed on CET Position Fluctuation Along the Casting Direction in Continuous Casting Billets

Under the current background of high-speed continuous casting, it is essential to investigate the effect of casting speed on the stability of the solidification structure and quality of billets. In this paper, a three-dimensional transient numerical model was established to simulate the continuous casting process, and the model was verified through the temperature measurement data and the actual solidification structure characteristics of billets. On this basis, the effect of casting speed on columnar to equiaxed transition (CET) position fluctuation along the casting direction was investigated, and the corresponding control measures of CET position fluctuation were presented. The internal quality stability of billets will not always deteriorate with the increase of the casting speed, and there is an optimal casting speed. Meanwhile, the casting speed can affect the fluctuation of the heat transfer by changing the molten steel convection fluctuation in billets, and finally, resulting in the fluctuation of CET position and central quality along the casting direction. Under a certain specific water amount, the fluctuation of liquid convection and heat transfer at the CET region is relatively decreased, and the solidification structure along the casting direction is more uniform when the casting speed is controlled in the intermediate range. During the high-speed continuous casting process, the cooling intensity of the secondary cooling can be appropriately increased, when the optimal casting speed is undeterminable, to reduce the CET fluctuation and improve the uniformity of the billets central quality. This paper can provide methods and theoretical references for determining the optimal casting speed and improving the internal quality of billets under the background of high-speed continuous casting.