| 摘要 |
PROBLEM TO BE SOLVED: To prevent pick-up of nitrogen in molten steel caused by flowing-in of the air from an immersion tube of a degassing facility, or the like. SOLUTION: In the immersion tube having a cylindrical core metal and a refractory lined in the periphery of the core metal, the immersion tube is constituted so that the core metal has at least one step of a horizontal projecting part continued on the outer periphery at the upper part from 1/2 of the total length of the core metal to the upper end of the core metal.
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