| 摘要 |
PURPOSE:To make it possible to utilize an inexpensive small piece cooling material having good shape and to exclude a defect due to the interruption of decarburization while reduce the amount to be required of O2-gas, in a decarburizing stage for blowing O2-gas and dilution gas into molten steel, by adding metal oxide after the intermediate period during carburization. CONSTITUTION:For example, in performing decarburization by an AOD process for simultaneously blowing Ar as dilution gas and O2-gas into molten steel, metal oxide, for example, a chromium ore, NiO, scale or an iron ore is added after the intermediate period of decarburization. Herein, the intermediate period during decarburization means a stage wherein C in molten steel reaches about 0.25% or less. By this method, metal oxide is reduced by Cr in the molten steel and it is supported that the formed Cr2O3 in the molten steel is reacted with C in the molten steel and contributes to decarburization. Because the oxygen concn. (Cr2O3 concn.) in the molten steel is kept high by thus added metal oxide, decarburization can be performed at the same speed as a conventional process by stirring without blowing O2-gas but only with blowing dilution gas. |
