| 摘要 |
PURPOSE:To obtain efficiently stainless steel contg. low nitrogen while preventing the adsorption of nitrogen by recarburizing the molten iron for Cr-contg. stainless steel in a bottom-blown converter and decarburizing it, thereaftaer feeding MgCO3 at the time of taking out the steel to a ladle and subjecting it to vacuum decarburization treatment. CONSTITUTION:Molten iron contg. >=10% Cr is recarburized in a converter provided with a bottom-blown tuyere so that the concn. of carbon is reached to >=4%. Then the flux consisting essentially of CaO and CaF2 is charged and the molten iron is bottom-blown with gaseous Ar or the like, decarburized and denitrified with the blowing of top-blown oxygen, thereafter the steel is taken out in a ladle. At this unloading of the steel, MgCO3 substance is fed in the ladle to generate gaseous CO2 and thereafter vacuum decarburization treatment is performed. In this process, since the steel is denitrified in a converter refining process and thereafter the steel is taken out while preventing the adsorption of nitrogen, the refining load can be decreased and the stainless steel contg. low nitrogen can be manufactured. |
