Refining method and refining apparatus for chromium-contained molten steel

摘要

A refining method and apparatus for decarburization refining of chromium containing molten steel in a vessel having a first step of blowing oxygen while the inside of the vessel is at a pressure of between 400 Torr and atmospheric pressure, a second step of blowing oxygen while evacuation the inside of the vessel to 250 to 400 Torr and a third step of blowing gas while evacuating the vessel to not more than 250 Torr. Further, a refining method and apparatus for ultra-low carbon chrome melt by performing a first vacuum refining until the third step, then restoring the pressure in the vessel to at least 400 Torr, then performing second vacuum refining while making the bottom blowing gas blow rate at least 0.4 Nm3 per to steel.