METHOD FOR CONTINUOUSLY CASTING STEEL AND PROCESS FOR PRODUCING STEEL SHEET

摘要

In a method for continuously casting an extremely low carbon steel using a continuous casting machine which includes a pair of upper magnetic poles and a pair of lower magnetic poles and an immersion nozzle having a molten steel discharge angle of 10° or more and 30° or less while braking a molten steel flow by DC magnetic fields applied to the upper magnetic poles and the lower magnetic poles respectively, by adjusting the chemical components of extremely low carbon steel within a specified range by taking into account an interface tension gradient in a concentration boundary layer on a front surface of a solidified shell, and also by optimizing intensities of the DC magnetic fields applied to the upper magnetic poles and the lower magnetic poles respectively corresponding to a slab width of a slab to be casted and a casting speed, it is possible to acquire the slab having high quality not only with the small number of defects caused by the entrainment of bubbles, non-metallic inclusion and a mold flux into the molten steel.