| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for treating molten steel excellent in a solidified structure by utilizing CaO with which the solidified structure of the molten steel is micronized at a low cost by adding Ca forming effective inoculation nuclei to the molten steel, and internal defects, such as internal crack, center segregation, center porosity, can be prevented. SOLUTION: The molten steel is cast after controlling a total Al content to <=0.03 wt.% and adding the Ca material 13 to the molten steel 11 so as to satisfy the following formula in the molten steel 11 havingγiron of solidified primary crystal. The formula is 0.0005 wt.%<=(total Ca wt.%)<=2.5×(total O wt.%). Wherein, the total Ca wt.% is a concentration of Ca contained in the molten steel and the total O wt.% is a concentration of O contained in the molten steel.
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