METHOD OF CONTINUOUSLY CASTING SMALL-SECTION BILLET

摘要

The invention provides a method of continuously casting a billet with a small cross section in which the billet has a cross sectional area not more than 500 cm 2 and a molten steel is poured into a mold using a cylindrical immersion nozzle with a single port, being characterized in that the molten steel level in the mold is measured using an eddy current sensor for molten steel level control in a mold, the molten steel surface level is controlled based on the thus-measured value, motion of molten steel in the mold is adjusted by applying electromagnetic stirring, a cooling zone during the final period of solidification is disposed within a certain region ranging from the meniscus to the specific site, a casting speed is adjusted so that the region in which the solid phase ratio at the billet center is 0.3-0.99 may be included in the cooling zone during the final period of solidification, and the specific amount of secondary cooling water, the billet surface temperature at the entrance to the cooling zone during the final period of solidification and the density of cooling water in the cooling zone during the final period of solidification are optimized. By this, billets with a small cross section can be continuously cast for various steel grades while stably and reliably reducing the occurrence of center porosity at the billet center and improving the billet inner quality.