IMPROVEMENT OF SLAB QUALITY OF ULTRA-LOW CARBON-STEEL IN CURVED MOLD TYPE CONTINUOUS-CASTING MACHINES

The casting speed of ULC-Ti steel in a curved mold type continuous cas ting machine used to be restricted by the formation of pencil pipe def ects. These defects being caused by Ar bubbles at the immersion nozzle , a casting method without addition of Ar gas has been developed. With this method, casting speed could be raised and, at the same time, the occurrence of pencil pipe defects and phosphorous slivers reduced. Th e increase in alumina slivers could partly be compensated for by the h igher casting speed made possible by the new casting method.