| 摘要 |
PROBLEM TO BE SOLVED: To provide a method, with which a high nitrogen steel containing a large quantity of nitrogen can be produced without such fear as to development of blow hole defect. SOLUTION: A refining apparatus, with which atmosphere can be controlled and a pressurized operation can be executed, is used and refining of molten steel is executed by regulating the nitrogen content in the atmosphere so as to be higher than that in the air or the operational pressure higher than the atmospheric pressure or making the nitrogen partial pressure high in the atmosphere with the above both methods. Then, the nitrogen with dissolvable concn. in the molten steel at the solidifying time of the molten steel, is added to the molten steel, and casting is executed under condition of keeping the high nitrogen partial pressure in the atmosphere to obtain a steel ingot. Nitrogen can be added by charging a nitride alloy together with the above method.
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