Method for continuous casting of steel, and method for manufacturing bar steel

Abstract

This method for continuous casting is provided with an extraction step for extracting a cast slab in a solid-liquid coexisting state from a cylindrical casting mold, a first rolling reduction step for performing rolling reduction of the cast slab in the solid-liquid coexisting state in a first rolling reduction direction perpendicular to the longitudinal direction of the cast slab after the extraction step, and a second rolling reduction step for molding the cast slab, in a completely solidified state in which the temperature of a center part thereof is higher than the temperature of a surface part thereof after the first rolling reduction step, into a rounded rectangle having rounded corner parts as viewed in cross-section perpendicular to the longitudinal direction of the cast slab, while performing rolling reduction alternately in the first rolling reduction direction and a second rolling reduction direction, the second rolling reduction direction being a rolling reduction direction orthogonal to both the first rolling reduction direction and the longitudinal direction of the cast slab.

Description

technical field [0001] The present invention relates to a continuous casting method for obtaining slabs (slabs) with excellent internal quality with less center segregation, less center porosity, and less internal cracks, and a method for manufacturing steel bars that can omit the blooming (block rolling) process. [0002] This application claims priority based on Japanese Patent Application No. 2012-183179 for which it applied in Japan on August 22, 2012, and uses the content here. Background technique [0003] Generally, high-grade (high-quality) steel bars are manufactured by casting a slab through a bloom continuous casting machine with a rectangular mold having a large cross-section, blooming the slab, and then casting steel sheet) rolling. The high-grade steel bar includes bar steel, wire rod and the like. In these steel bars, center segregation and center porosity formed at the end of solidification of the continuous casting slab lead to deterioration of material pr...

AI Technical Summary

Problems solved by technology

However, in such a case, there is a problem that internal cracks are generated in the slab at the time of unsolidified reduction, impairing the material properties of the steel bar

However, there has not been developed a continuous casting technology that can obtain a slab with excellent internal quality with less center segregation, less center porosity, and less internal cracks, and can also improve the productivity of the slab.

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