| 摘要 |
PROBLEM TO BE SOLVED: To enable the production of a beam blank excellent in surface characteristic without developing surface crack. SOLUTION: At the time of producing the beam blank by using a rolling reduction apparatus provided with one pair of horizontal rolls and one pair of vertical rolls and simultaneously executing the rolling reduction from the upper and lower direction and the right and left direction to a cast slab having rectangular cross section, in which the unsolidified part exists in the inner part, at least one side between casting speed and secondary cooling water flowing rate, is controlled. In this way, the surface temp. of the cast slab at the time of executing the rolling reduction is adjusted to <=750 deg.C or >=880 deg.C.
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