| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for continuously casting a steel for an extra-thick steel plate such as a bridge and a construction member, and a continuously cast slab produced using the continuous casting method by which the internal quality of an extra-thick steel plate subjected to rolling can be surely assured. SOLUTION: In the continuous casting method, a slab is subjected to bulging, and thereafter, the slab including a unsolidified part 10 is subjected to rolling reduction. The bulging amount is controlled to 2 to 20 mm, and the slab in the unsolidified part in which the thickness of the equiaxed crystals on the upper half face side from the central part of the slab thickness is≥5 mm and the average central solid phase ratio in the width direction of the slab is 0.85 to <1.0 is subjected to the rolling reduction using at least a pair of rolling reduction rolls 7 under the condition where the draft in the thickness direction of the slab reaches≥2%. According to this invention, the production of a slab having a remarkably reduced porosity is made possible, and, by using the slab, an extra-thick steel plate of high quality even at a low rolling ratio can be produced. COPYRIGHT: (C)2007,JPO&INPIT
|
