| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for manufacturing a thick steel plate of tensile strength of 400 N/mm<SP>2</SP>class with excellent scale property. SOLUTION: A steel slab or a cast slab in which the steel composition expressed by mass % is≤0.40% in terms of carbon equivalent Ceq defined as "Ceq=C+Si/24+Mn/6+Ni/40+Cr/5+Mo/4+V/14" is reheated to the temperature of≤1,150°C, the rolling thereof is completed at the roll-in temperature of a final rolling pass of 870-980°C, the water cooling is started within two minutes after the rolling from the temperature of≥720°C, the cooling is performed for≥50°C from the rolling start temperature, and the water cooling is stopped at the temperature of≥600°C. In addition, in at least two final passes of the rolling, preferably, descaling with high-pressure water is not performed. When a thick steel slab or cast slab is subjected to laser cutting, C amount is preferably 0.15%. COPYRIGHT: (C)2004,JPO&NCIPI
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