| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for utilizing a vacuum-degassing apparatus by which the stuck metal in a degassing vessel during operation can be removed in the wide range without affecting decarburization-refining time for an extra low carbon steel. SOLUTION: The method for using the vacuum-degassing apparatus, in which molten steel tapped from a primary decarburization-refining furnace into a ladle is held and both of a middle or low carbon steel and the extra low carbon steel as the producing target are alternately changed over and again refined, is improved. In the case of producing the middle or low carbon steel, the molten steel under rimmed state from the primary decarburization-refining furnace is tapped into the ladle and this molten steel is vacuum-decarburized with the vacuum-degassing apparatus and also, oxygen gas is blown into a space part on the molten steel surface in this vacuum vessel through a lance for oxygen-blowing inserted into this vacuum-degassing apparatus, and after melting the stuck metal in the vacuum vessel by secondarily burning the generated CO gas in the bath, the produced heats performing the deoxidation of the molten steel and the adjustment of composition are performed at least several times and thereafter, the production of the extra low carbon steel is performed. COPYRIGHT: (C)2006,JPO&NCIPI
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