The demands for surface quality assurance of sheets and plates have been increased in recent years, reflecting the users' requirement for higher grade steel. To meet these requirements, a number of countermeasures, such as pursuing extremely clean molten steels and conditioning low-grade portion have been taken. These approaches, however, lead to a loss of profitability as consequences of the decrease in productivity and the steel yield of prime-quality products. Therefore we have to stabilize even the surface quality of commercial grade steel. In the continuous casting process, it is important to reduce the off-quality portion due to ladle changing or variation in process parameters. Based on these viewpoints, Kimitsu Works in Nippon Steel Corporation has been active in controlling slab surface quality by use of molten metal flow control, without by use of the nozzle stream, and consequently a new in-mold electromagnetic stirrer (hereinafter abbreviated to "EMS") was installed. This study reports the features and design concept of the new EMS, the resulting effects on slab quality, and theoretical consideration on effects of initial solidification and cleanliness of slab.
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