METHOD FOR CONTINUOUS CASTING OF STEEL

摘要

The objective of the present invention is to provide a high-quality slab, particularly without corner cracking, by reliably suppressing surface cracks in the slab by controlling the temperature of the corner part of the slab by means of a secondary cooling while using a casting mold having an appropriately shaped casting space, which conventionally has not been sufficiently achieved merely by controlling the slab structure by means of a secondary cooling. In this continuous casting method, wherein a casting mold is charged with molten steel and a slab is drawn directly from the casting mold, the casting slab that is used has a casting space for which the four corners of a rectangular space defined by a pair of long sides and a pair of short sides are removed in a right-angled triangular shape such that the ratio (b/a) of the length (b) on the short sides of the casting mold to the length (a) on the long sides of the casting mold is between 3.0 - 6.0. In addition, before reaching the straightening point the surface temperature of at least the corner parts of the slab is lowered to equal to or less than the AR3 point from directly beneath the casting mold, and then the surface temperature of at least the corner parts is raised to 800°C or higher, after which the straightening point is passed through at 800°C or higher.