| 摘要 |
PROBLEM TO BE SOLVED: To provide an evacuating method with which the spattering of molten steel and the raise-up of the molten steel surface in a ladle can be prevented, in a process for reducing the pressure to a targeted vacuum degree by evacuation of a vacuum vessel when a vacuum-refining of an Al-containing steel is performed. SOLUTION: The pressure reducing speed in the vacuum vessel is set according to Al adding quantity per ton of the molten steel. Then, in the case of using W (kg/ton) as Al adding quantity and M (Pa/min) as pressure reducing speed, it is desirable to reduce the pressure within the range satisfying 0<M<=(1.50/W)+2.25.
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