MULTI-STEPPED IMMERSION NOZZLE FOR CONTINUOUS CASTING.

摘要

This invention is characterized by providing a plurality of steps for the molten steel flowing hole of the immersion nozzle for continuous casting, in which inner diameters d<5>, d<6>, and d<7> of said molten steel flowing hole at stepped parts are in such relations that d<5> > d<6> > d, or d<5> > d<6> > d<7> > d, where d is the main inner diameter, and the inner diameter d<6> or d<7> at the part immediately above the molten steel discharge opening is such that (d + 10 mm / d<6> or d<7>), and the material of the inner peripheral wall near the molten steel discharge opening is desirably boron-nitride-carbon. Such a composition as above is very effective in preventing deposit and adhesion of Al<6>O<7> and is capable of improving the life of nozzle 50% over that of the conventional one.