The use of slag deoxidant during tapping from the converter is commonly adopted practice to improve the steel cleanness of ultra-low carbon steel. However, the addition of slag deoxidant causes difficulty in decarburization at RH by unnecessary reduction of free oxygen in molten steel. Therefore, oxygen has to be injected for effective decarburization in ultra-low carbon steel and that causes reoxidation between RH treatment and continuous casting by increasing (FeO) and (MnO) in slag. The Double Slag Deoxidation (DSD) method has been developed to solve such reoxidation problem. In the DSD method, part of slag deoxidant was added just after tapping and additional slag deoxidant was added after decarburization in RH.
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