| 摘要 |
PROBLEM TO BE SOLVED: To provide a producing method of an extra-thick steel plate, with which the extra-thick steel plate excellent in the internal quality can stably be produced at <3 draft. SOLUTION: A continuously cast slab having (d0) center porosity thickness rolled at the draft (r) satisfying the formula (I): r>=0.2×d0+1.0 after heating at 900-1300 deg.C, and in the last rolling pass, a condition to satisfy the formula (II): 1.67×[(t0-t1)×R]1/2/t0+0.5>=1.1 is obtained. Wherein, t0: the thickness (mm) before the last rolling pass of the rolling slab, t1: the thickness (mm) after the last rolling pass of the rolled slab and R: the radius (mm) of the rolling roll.
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