| 摘要 |
PROBLEM TO BE SOLVED: To provide continuously cast pieces of high quality, particularly billets in a precisely square cross section, their manufacturing method, and a continuous casting equipment for execution therefor. SOLUTION: In the continuous caster for billet, the secondary cooling water is controlled to stably produce cast steel pieces with good central segregation at a low cost. Weaker cooling on the sides of the cast piece than cooling on the top and bottom sides prevents centralization of the final solidification point into the center as is the case with a usual cast billet, spreading the segregation area horizontally into a flat oval shape as if it were a cross section of a bloom. This enhances reduction efficiency of unsolidified portion at light reduction so that application of light reduction not less than 5 mm of draft reduces flow of concentrated molten steel caused by solidification shrinkage in the cast steel piece.
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