| 摘要 |
PURPOSE: A method for manufacturing ultra-low phosphorus steel by performing converter refining operation even without using of temperature increasing material such as ferrosilicon (Fe-Si) or silica in converter by increasing content of silicon (Si) in molten iron and increasing temperature of molten iron. CONSTITUTION: The method for manufacturing ultra-low phosphorus steel comprises the steps of dephosphorizing molten iron tapped from blast furnace in the molten iron pretreatment process; preparing molten iron by mixing dephosphorized molten iron with ordinary molten iron to a certain mixing ratio so as to secure certain ratios of mixed molten iron constituents and certain temperature of molten iron; pouring the mixed molten iron into a ladle to be changed into converter; and charging the mixed molten iron poured into the ladle into the converter so that the mixed molten iron is refined to a phosphorus content of 110 ppm or less in the converter, wherein 70 to 40 wt.% of the dephosphorized molten iron and 30 to 60 wt.% of the ordinary molten iron are mixed with each other, and wherein the mixed molten iron comprises 0.13 to 0.22 wt.% of Si and 0.04 to 0.059 wt.% of P, and the temperature of molten iron is in the range of 1,270 to 1,315 deg.C.
|
