Patent ID: 8277537

Claim:
A method of manufacturing an ultra low carbon ferritic stainless steel comprising: tapping molten steel to a ladle in a non-deoxidized state after pre-decarburization and denitrification in an argon oxygen decarburization refining furnace and then removing non-deoxidized slag; placing the ladle in a vacuum furnace, reducing pressure and then blowing-in oxygen gas from the upper of the molten steel through a lance; creating Al 2 O 3 by injecting Al at point of time of beginning of oxygen blowing; forming CaO—Al 2 O 3 —Cr 2 O 3 —MgO-based slag by injecting calcium oxide at point of time of completion of the oxygen blowing; and supplying inert gas through a porous plug on a bottom of the ladle, wherein the CaO—Al 2 O 3 —Cr 2 O 3 —MgO-based slag is indicated as (wt % CaO)/(wt % Al 2 O 3 ): 0.5 to 1.0, Cr 2 O 3 : 15 to 60 wt %, and MgO<7 wt %.