Smelting method of cleanliness in excellent ultra-low carbon steel

摘要

PROBLEM TO BE SOLVED: To provide a melting method of an extra-low carbon steel excellent in the cleanliness while restraining lower oxide content to low level without blowing gaseous oxygen at the time of executing a vacuum decarburizing treatment. ;SOLUTION: The contents in slag in a ladle before the vacuum treatment are adjusted to 0.6-2.0 CaO/Al2O3 ratio of CaO content to Al2O3 content and 2-10 wt.% the total of FeO and MnO contents, ≤12 wt.% SiO2 content and 5-10 wt.% Mg content. Successively, the decarburize-treatment is executed on the molten steel and further, in order to execute deoxidize-treatment, Al is added into the molten steel, and simultaneously or thereafter, the oxide- containing MgO is added into a vacuum vessel to produce the steel having ≤0.005 wt.% carbon content.;COPYRIGHT: (C)2000,JPO