| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a method for refining molten steel with which a nozzle clogging in the time of continuous-casting caused by low melting point inclusion and the surface defect on a rolled steel sheet, can be prevented. <P>SOLUTION: A simple ladle-refining method, with which the molten steel in the ladle is refined while performing Ar gas stirring in the atmospheric pressure, is used. Rare-earth metal elements (REM) are added into the molten steel deoxidized with Al or Al-Si, and the additional quantity of the REM supplied into the molten steel is in the range of 5-20 ppm to the molten steel mass, and the REM-additional timing is after adjusting the finish-components, and the time from the starting of this addition to the finishing of this treatment, is performed at the timing of uniform mixing time or shorter. Then, the formed inclusions are made to be high melting point and harmless by forming the inclusion composition with mass ratio into 1-25% CaO, 8-95% Al<SB>2</SB>O<SB>3</SB>and 3-90% REM oxides. <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
