Patent ID: 8397792
Filing Date: 2013-03-19
Classification: B22D

Abstract:
1. A round billet continuous casting method in which a round billet continuous casting mold is used, the round billet continuous casting mold having an upper edge, a lower edge, and a cooled mold surface extending between the upper and lower edges, the mold also having an inner diameter D o (m) at the lower edge thereof, and an outer curvature side thereof is configured to have a curvature radius R 0 (m) at the lower edge thereof, wherein D is a mold inner diameter at a distance x away from the upper edge of the cooled mold surface and dD/dx represents a change in D with respect to a change in x, and R is a curvature radius of an outer curvature side at a distance x away from the upper edge of the cooled mold surface and dR/dx represents a change in R with respect to the change in x, the mold being characterized in that: given that a rate of change Tp (%/m) in mold inner diameter per unit length along a casting direction is expressed by Formula 1, and a rate of change Rp (%/m) in curvature radius of an outer curvature side per unit length along the casting direction is expressed by Formula 2, the rate of change Tp in mold inner diameter and the rate of change Rp in curvature radius satisfy a relationship expressed by Formula 3; wherein the method comprises feeding a mold powder onto a surface of a molten steel while pouring the molten steel into the continuous casting mold, the mold powder having a viscosity of 0.1 to 1.0 Pa·s at 1573K, a solidification temperature of not less than 1273K, and a mass % ratio of 1.0 to 1.4 in terms of (CaO+CaF