IMMERSION NOZZLE WITH SPLIT-TYPE WEIR, AND METHOD FOR CONTINUOUSLY CASTING MEDIUM AND HIGH CARBON STEEL USING THE IMMERSION NOZZLE WITH SPLIT-TYPE WEIR

摘要

This invention provides an immersion nozzle which can suppress channeling in the thickness and width directions of a mold. This nozzle is a closed-end cylindrical immersion nozzle (1) for pouring a molten steel held in a tundish into a mold. A pair of opposed molten steel delivery holes (3) are bored on the peripheral wall of the immersion nozzle (1) at a position distant upward by a predetermined distance from an inner bottom face (2) of the immersion nozzle (1). In the inner bottom face (2), as viewed from the bottom face of the immersion nozzle (1), a pair of protrusion parts (4, 4) extended parallel to a borehole direction (3A) in the molten steel delivery hole (3) are provided on an identical row. The immersion nozzle further satisfies the following formulae (1) and (2). h/H = 0.5 to 2.0 (1) c/Dsn = 0.1 to 0.6 (2) wherein h: the height of the upper face of the protrusion part in the vertical section to the direction of extension of the protrusion part; H: the distance between the lower end of inner peripheral-side opening edge in the molten steel delivery hole and the inner bottom face; c: the distance between a pair of protrusion parts; and Dsn: the inner diameter of the immersion nozzle.