Abstract
A low-expansion type MgO-C material was newly developed as nozzle materials for continuous casting. The alumina-buildup characteristics and concentration changes of the molten steel were evaluated by an erosion/
corrosion test with comparing the MgO-C with Al2O3-C or Al2O3-SiO2-C materials under the same vol% of C. The average alumina-buildup rate became lower in the order of MgO-C, Al2O3-C, Al2O3-SiO2-C. Therefore, the rate of alumina-buildup decreased for the MgO-C. The concentration changes of C in the molten steel were studied before and after the test, C in molten steel with MgO-C material was lower than that of Al2O3-SiO2-C, by approximately 40%. The alumina-buildup rate in the MgO-C was lower than those of Al2O3-C or Al2O3-SiO2-C materials and less inclusions from refractories were dissolved into the molten steel. It was attributed to be low permeability of a smooth and highly dense continuous layer with high MgO content formed on the hot face.
