Extremely, low carbon and the pole the transmit to decarbonize make the mannered null containing

摘要

PROBLEM TO BE SOLVED: To provide a method for efficiently refining an extra-low carbon and extra-low nitrogen stainless steel at a low cost which restrains the oxidation loss of chromium contained in molten steel as little as possible in comparison with the conventional method and shortens or omits a vacuum decarburizing process. ;SOLUTION: The refining method of the extra-low carbon and extra-low nitrogen stainless steel is executed by tapping into a ladle after supplying oxygen into the Cr-containing molten steel and decarburizing to a fixed [C] concn. and thereafter, executing further the decarburization with the oxygen supply under reduced pressure, decarburization under vacuum and reduction treatment. In such a case, the first decarburization with the oxygen supply is executed to the range of 0.25-0.10 wt.% [C] concn. and this molten steel is tapped into the ladle without deoxidizing. The decarburization with the oxygen supply under reduced pressure thereafter, is executed under condition of ≥5 Nl/min/t flow rate of bottom-blown inert gas and ≤15 kg/t wt. of produced slag.;COPYRIGHT: (C)1999,JPO