1. College of Materials Science and Engineering, Chongqing University, Chongqing 400044, China; 2. Chongqing Key Laboratory of Vanadium-Titanium Metallurgy and New Materials, Chongqing University, Chongqing 400044, China
Abstract：Nowadays,the development of the steel industry needs to improve the quality uniformity and stability of the continuous casting billets. The centerline segregation formed in the continuous casting process represents the nonuniformity of solute elements and quality of the billets,which is closely related to the solidification process of solute-enriched liquid in the centerline of the billets. At the same time,the final electromagnetic stirring (F-EMS) and mechanical soft reduction (MSR) are widely used in the actual continuous casting process to improve the inner quality uniformity of the billets. However,the fluctuation of the solidification end point will affect the effect uniformity of the F-EMS and MSR. Thus,it′s essential to investigate the solidification behavior and fluctuation characteristics in the centerline and explore the fluctuation of the solidification end point for improving the quality uniformity of the billets. It′s found that the fluctuation of solid fraction in the centerline will cause the fluctuation of the local cooling rate, and ultimately affect the quality uniformity of the billets. Subsequently, this work has analyzed the fluctuation periods of solid fraction and local cooling rate in the centerline of the billets and proposed the periodic fluctuation mechanism of the solidification end point in the continuous casting process. At the same time,the judgment equation of fluctuation distance of solidification end point under different casting speeds was obtained. On this basis,the effect of casting speed on the fluctuation of solid fraction in the centerline was discussed,and the influence of fluctuation distance of solidification end point on the effect uniformity of the F-EMS and MSR was also analyzed. The results show that the increase in casting speed can reduce the fluctuation degree of solid fraction and improve the inner quality uniformity of the billets. On the other hand,although the fluctuation distance of the solidification end point increases with the increase of the casting speed,its influence degree on the effect uniformity of the F-EMS and MSR is gradually reduced due to the increase of the liquid core length.
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2023, Vol. 58 
