| 摘要 |
PROBLEM TO BE SOLVED: To provide the method for adjusting nitrogen concn. in molten steel by which the nitrogen concn. in the molten steel in a vacuum degassing apparatus can be adjusted more precisely than the conventional method. SOLUTION: At the time of adjusting the nitrogen concn. in the molten steel to a target value by blowing gaseous nitrogen into the molten steel held in the vacuum degassing apparatus and simultaneously, reducing the pressure in this apparatus to the nitrogen partial pressure achieving the equillibrium nitrogen concn. in the molten steel, the nitrogen concn. in the molten steel is quickly measured on the way of the adjustment. Then, the measured value is compared with the increasing or the decreasing scheduled value at this point of time, and the pressure in the apparatus is changed so as to eliminate the deviation.
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