Abstract: With a view to adding, to an upper nozzle formed with a bore having a shape capable of creating a less energy loss or smooth (constant) molten steel flow to suppress the occurrence of adhesion of inclusions and metals in molten steel, a gas injection function to thereby further suppress the occurrence of the adhesion, the present invention provides a method of using an upper nozzle configured to have a cross-sectional shape of a wall surface defining the bore, taken along an axis of the bore, comprising a curve represented by the following formula: log(r (z))=(1/n)×log((H+L)/(H+z))+log(r (L)) (n=1.5 to 6), where: L is a length of the upper nozzle; H is a calculational hydrostatic head height; and r (z) is an inner radius of the bore at a position downwardly away from an upper edge of the bore by a distance z. The method comprises using the upper nozzle in such a manner as to satisfy the following relationship: RG?4.

Abstract: With a view to adding, to an upper nozzle formed with a bore having a shape capable of creating a less energy loss or smooth (constant) molten steel flow to suppress the occurrence of adhesion of inclusions and metals in molten steel, a gas injection function to thereby further suppress the occurrence of the adhesion, the present invention provides a method of using an upper nozzle configured to have a cross-sectional shape of a wall surface defining the bore, taken along an axis of the bore, comprising a curve represented by the following formula: log(r (z))=(1/n)×log((H+L)/(H+z))+log(r (L)) (n=1.5 to 6), where: L is a length of the upper nozzle; H is a calculational hydrostatic head height; and r (z) is an inner radius of the bore at a position downwardly away from an upper edge of the bore by a distance z. The method comprises using the upper nozzle in such a manner as to satisfy the following relationship: RG?4.

Abstract: The present invention provides an SN plate capable of being formed in a large size while using a highly corrosion resistant and highly thermally expansible refractory product. In the SN plate of the present invention, a specific refractory member 1a having a thermal expansion rate as measured at 1500° C. of 1.15 to 2.50% due to addition of aluminum for improving corrosion resistance is arranged as a part of the SN plate to cover at least a practically critical region of the SN plate. A thickness of the specific refractory member is set in a range of 15 to 25 mm. A portion of the SN plate other than the specific refractory member is made up of an unburned or burned refractory product consisting primarily of an alumina-carbon composite.

Abstract: The present invention provides an SN plate capable of being formed in a large size while using a highly corrosion resistant and highly thermally expansible refractory product. In the SN plate of the present invention, a specific refractory member 1a having a thermal expansion rate as measured at 1500° C. of 1.15 to 2.50% due to addition of aluminum for improving corrosion resistance is arranged as a part of the SN plate to cover at least a practically critical region of the SN plate. A thickness of the specific refractory member is set in a range of 15 to 25 mm. A portion of the SN plate other than the specific refractory member is made up of an unburned or burned refractory product consisting primarily of an alumina-carbon composite.