| 摘要 |
PROBLEM TO BE SOLVED: To prevent generation of HIC caused by a residual bubble to a casing piece of inert gas blown into molten steel, and to prevent blocking-up of an immersion nozzle by sticking of a nonmetallic inclusion such as alumina.SOLUTION: A continuous casting method is provided for continuously casting the molten steel 1 while blowing the inert gas via an upper nozzle 13 into the molten steel of flowing down in a molten steel outflow hole 22, and the nozzle is provided with a plurality of gas blowing-in through-holes having the outer periphery covered with a steel shell and having a diameter penetrating through the inner periphery from the outer periphery of 100-400 μm, and mixed gas of Ar gas, Ngas or the Ar gas and Ngas of 2-15 NL/min is blown into the molten metal, by using the upper nozzle of setting the installation number of gas blowing-in through-holes so that gas back pressure when blowing the mixed gas of the Ar gas, the Ngas or the Ar gas and the Ngas of 2-15 NL/min into the molten metal from the upper nozzle, becomes 1.5 kgf/cm(≒147kPa) to 5.0 kgf/cm(≒490kPa). |
