| 摘要 |
PROBLEM TO BE SOLVED: To improve degassing speed and to remarkably shorten treating time of molten steel without bringing about increases of an equipment cost and the running cost by controlling a parameter calculated from circulating speed, cross-sectional area in a vacuum vessel and bath depth in the vacuum vessel in a specified range. SOLUTION: Molten steel after blowing in a converter, in tapped into a ladle and the ladle is transferred to an RH to execute degassing treatment. At this time, the parameter X is controlled to in the range of 0.3-1.0. Then, the parameter X=Q/(H.A1/2) and wherein, Q: the circulating speed (m3/s), A: cross-sectional area (m2) in the vacuum vessel, H: the bath depth (m) in the vacuum vessel. Concretely, the control of the parameter X is suitably adjusted to The circulating speed Q and the bath depth H in the vacuum vessel, because the cross-sectional area A in the vacuum vessel is constant. In this way, the RH treating time can be shortened by >=25% and this cost is reduced to a half and also, matching of a production pitch with a continuous casting method can be obtd. in good condition.
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