Modeling on Fluid Flow and Inclusion Motion in Centrifugal Continuous Casting Strands
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CENTRIFUGAL continuous casting (CCC) is an industrial steel casting process during which molten steel is injected into a round mold. During the pouring stage, the entire system is rotated along its axis at a certain rotational speed. The molten steel flows down into the mold through a no-straight nozzle, and once touching the side wall of mold, the molten steel rotates and moves towards the inner surface of the copper mold due to the centrifugal force stemming from the spinning mold. The solidifying shell grows as the steel is continuously withdrawn from the bottom of the mold. In the secondary cooling region, the back-up rolls around the round billet also spin in order to rotate the billet at the same rotation speed to that of the copper mold. There are very few reported studies on steel centrifugal continuous casting. However, the centrifugal ingot QIANGQIANG WANG, Ph.D. Student, and LIFENG ZHANG, Professor, are with the School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing (USTB), Beijing 100083, China. Contact e-mail: [email protected] SEETHARAMAN SRIDHAR, Professor, is with International Digital Laboratory, University of Warwick, Coventry, CV47AL, UK. Manuscript submitted December 2, 2015. Article published online May 26, 2016. METALLURGICAL AND MATERIALS TRANSACTIONS B
or pipe casing technology using horizontal or vertical devices has been developed for several decades and applied for the production of steel pipes.[1–4] In 1957, the horizontal centrifugal casting was used to produce 50-mm pipes.[1] Due to the fact that the technique has not yet been optimized in the early days, the rejection ratio of cast pipes at several plants all exceeded permissible standards. In 1958, pipes with 200 to 600 mm diameter were cast by centrifugal casting which had both vertical and horizontal forms.[2] It was reported that the wear resistance of a high-strength cast iron with centrifugal casting averaged 220 pct higher than that by stationary ingot casting.[3] Characteristics of the centrifugal casting include the following: – Relatively less defects than traditional stationary casting; – More non-metallic inclusions toward the bore so that they can be machined off; – Better mechanical properties; – Higher production rate; and – Possible to be used to functionally fabricate gradient metal matrix composite materials. The concept of producing castings in a rotating mold under a continuous operation can date back to 1904 and can be found in several patents.[5–7] It was designed to
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cast pipes. During pouring, the finished casted pipes were pulled out without stopping the rotation of the mold. For CCC system, the fluid flow plays an important role as the high-speed discharging flow has a great influence on gas entrainment, motion of inclusions,[8,9] shell formation, and the lifetime of copper mold. It is difficult to watch or measure the fluid flow velocity and multiphase phenomena in continuous casting strands because of the opaque nature of the melt and the mo
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