Molten steel desulfurization and dehydrogenation method with small refractory melting loss

摘要

PROBLEM TO BE SOLVED: To provide a slag composition range having no obstacle to a desulfurizing reaction and little erosion of a refractory, and a desulfurizing and dehydrogenating treating method particularly, related to a product which does not need so severe to [S] content, shortening the dehydrogenating treating time with the optimum stirring force while restraining the stirring force. SOLUTION: At the time of refining molten steel under reduced pressure, the desulfurizing and dehydrogenating treatment is executed with a slag composition comprising CaO-Al2 O3 -SiO2 -MgO-CaF2 as main components and having the following composition. That is, this slag composition is made to be 5-15% MgO, =10% CaF2 , =3 CaO/SiO2 and 1-3 CaO/SiO2 . Further, in the desulfurizing and dehydrogenating method of the molten steel, a flux for adjusting slag components or a flux for refining is added into a ladle before executing the desulfurizing and dehydrogenating treatment of the molten steel and the stirring is executed with inert gas under reduced pressure.