CONTINUOUS CASTING METHOD FOR STEEL, AND UPPER NOZZLE OF CONTINUOUS CASTING TUNDISH

摘要

PROBLEM TO BE SOLVED: To provide a continuous casting method for steel capable of preventing clogging of a nozzle at a molten metal discharging port, which extends from the upper nozzle of the continuous casting tundish to an immersion nozzle, further preventing generation of defects of steel products, and preventing operational troubles such as break-out by securing a sufficient layer thickness of mold powder, and to provide an upper nozzle of a continuous casting tundish.;SOLUTION: An upper nozzle 3 of a tundish is provided with two (upper-stage and lower-stage) gas blowing parts, which are made of porous brick. The pore diameters of the porous brick of an upper-stage gas blowing part 3a are smaller than those of the porous brick of a lower-stage gas blowing part 3b. The upper-stage gas blowing part and the lower-stage gas blowing part can blow gas independently. Using the upper nozzle 3 of a tundish in casting, Ar gas is blown from the upper-stage gas blowing part, and nitrogen gas or a mixture of nitrogen gas and Ar gas is blown from the lower-stage gas blowing part.;COPYRIGHT: (C)2009,JPO&INPIT