Nippon Steel Corporation

Toyoichiro Higashi

Masahiro Doki

Shigenori Tanaka

Mitsuo Uchimura

Jun Fukuda

Hiroshi Ohba

A billet produced by continuous casting having little central segregation, in particular a billet of high carbon steel produced by continuous casting, and a manufacturing method therefor are provided. In the continuous casting billet, the size of the dendritic equiaxed crystal in a billet central portion is reduced to be not more than 6 mm. For this purpose, electromagnetic stirring is performed so that the inclining angle of the primary dendrite within 10 mm of a billet surface layer is increased to be not less than 10&#xb0;. Furthermore, the mechanical soft reduction is performed during continuous casting so that the diameter of the center porosity in the billet central portion is reduced to be not more than 4 mm. Thereby, in particular in the manufacturing of the continuous casting billet having a carbon content of not less than 0.6% by mass and a billet size of not more than 160 mm can be provided a billet in which breaking troubles in wire drawing after rolling to a rod are reduced by reducing the central segregation in the billet.

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Kimitsu, Japan

Toyoichiro Higashi