METHOD FOR UNIFORMING TRACE AMOUNT OF RARE-EARTH ELEMENT ADDED INTO MOLTEN STEEL

摘要

PROBLEM TO BE SOLVED: To provide a method for uniforming a trace amount of REM element added into molten steel by which the yield of the REM can be improved, the treating time can be shortened and the REM concentration can be uniformed as the same degree as before.;SOLUTION: Into the molten steel deoxidized with Al or Al-Si, the rare-earth elements of one or more kinds selected from among Ce, La, Pr and Nd are added in a trace amount and this molten steel is stirred for a period of time 0.1-0.9 times of a uniformly mixing time τ. As the uniformly mixing time τ, time is used which is defined as the time in which the concentration of S reaches ±5% of the balancing concentration in the case of using S added into the molten steel as a trace. Since the specific gravity of the REM is large, after deeply dipping into the molten steel with the inertial force of the charging from the upper part, the REM is gradually widened into the whole ladle while carrying in the inertial convection after the stirring-treatment of the molten steel in the ladle is performed and thus, the stirring time is shortened.;COPYRIGHT: (C)2005,JPO&NCIPI