| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a nitrogen absorption preventing method more effective than the conventional air infiltration preventing technique through an RH (Ruhrstahl-Heraeus) immersion tube. SOLUTION: In the method of preventing the infiltration of nitrogen into molten steel by coating the molten steel with slag, a slag having a composition which contains Fe2O3, FeO, MnO, CaO, Al2O3 and SiO2 and in which the concentrations of Fe2O3, FeO and MnO are made, in total, to <=8% by mass and the ratio between CaO and Al2O3 by mass, CaO/Al2O3, is regulated to 0.95-2.7 and also the ratio between Al2O3 and SiO2 by mass, Al2O3/SiO2, is regulated to <=0.39 is used.</p> |
