Effect of TurboSwirl Structure on an Uphill Teeming Ingot Casting Process
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produced by ingot casting is smaller than that produced by continuous casting, the method is still frequently used by manufacturers of special steel, such as forgings and low-alloyed steel. In addition, ingot casting is suitable to produce a final steel with a huge geometry up to several hundred tons. Two methods are widely used to pour the molten steel from the ladle into the ingot mold, top pouring, and bottom pouring.[1] The choice of pouring method is important and is determined by the final use of the steel ingots. Bottom pouring (uphill teeming) results in an ingot steel with a better surface quality. More specifically, it leads to a more stable cast due to the lower turbulence in the pouring process. During the uphill teeming process, the flow pattern plays a very important role, since an inappropriate flow pattern may induce a high velocity of the liquid steel before it is poured into the mold and mold flux HAITONG BAI, Ph.D. student, MIKAEL ERSSON, Assistant Professor, and PA¨R JO¨NSSON, Professor, are with the Department of Materials Science and Engineering, KTH Royal Institute of Technology, Brinellva¨gen 23, 10044 Stockholm, Sweden. Contact e-mail: [email protected] Manuscript submitted September 16, 2014. Article published online September 4, 2015. 2652—VOLUME 46B, DECEMBER 2015
entrapment may occur. Steps must therefore be taken to control the flow pattern. Several improvements have been investigated by previous researchers. Eriksson et al.[2] designed a flaring angle at the entrance of the mold, which could reduce the velocity of liquid steel entering the mold, resulting in a more stable surface and avoiding a mold flux entrapment. Another way to the control flow pattern was to generate a swirling flow, which had been used in numerical simulations and in water modeling experiments on the continuous casting nozzle.[3–5] In this case, a twist-tape swirl blade was placed in the SEN to let the liquid steel rotate, and this could reduce the uneven flow in a continuous casting mold, as shown by Yokoya et al.[6] Hallgren et al.[7] inserted the swirl blade into either the horizontal or the vertical runner of the ingot casting system and the computational fluid analysis indicated that this give a much more uniform flow pattern with a calmer filling process. An even smaller hump height and axial velocity can be obtained by using both a divergent nozzle and a swirl generator, as shown in both water model and mathematic models of an uphill teeming process[8] Zhang et al. also implemented a swirl blade at a vertical position at the inlet nozzle of a mold in an uphill teeming casting system, and showed that quite a uniform velocity distribution and stable flow pattern can be obtained at the divergent nozzle of the mold.[9] A METALLURGICAL AND MATERIALS TRANSACTIONS B
plant trial of an uphill ingot casting process with a swirl blade showed a calmer filling than filling without the swirl blade.[10] The direction at which the swirl blade is placed in the vertical runner can also affect the flow pattern, and the use of a swirl blade can d
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