| 摘要 |
PROBLEM TO BE SOLVED: To provide a method with which refining of high carbon low phosphorus steel can be performed without using fluorite while restraining operational problems with refractory, slopping and the generation of harmful inclusion causing quality problems. SOLUTION: In a decarburization with a refining apparatus having a top- bottom combined blowing function by using the molten iron lowering the phosphor concentration to <=0.050% [P] with a dephosphorizing treatment, this dephosphorization method of the molten high carbon steel is performed, by which in the case of using (%Al2 O3 ) as Al2 O3 concentration and (%SiO2 ) as (SiO2 ) concentration contained in the slag at tapping of oxygen blowing, (% Al2 O3 )+(%SiO2 ) is regulated to 10-30% and (%Al2 O3 )>(%SiO2 ), and the fluorite concentration in the slag is regulated to <=0.5%.
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