| 摘要 |
PROBLEM TO BE SOLVED: To stabilize the pickup of nitrogen content in each heat at the time of adding a wire into molten steel by specifying the grain size of metallic calcium or calcium compound in a calcium-packed wire. SOLUTION: In the calcium-packed wire formed by coating the metallic calcium or the calcium compound for adding the calcium into molten steel with a steel hoop, the metallic calcium or the calcium compound is used in the range of 150μm-1mm grain size. The calcium compound is desirable to use the calcium-silicon alloy. By this constitution, vigorous reaction between the molten steel and the calcium can be restrained and chance, in which new molten steel surface becomes in contact with the air, is reduced and the pickup of the nitrogen content in the molten steel can be reduced. Further, the development of dust at the feeding position of the wire is reduced and the good operational circumference can be kept.
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