| 摘要 |
PROBLEM TO BE SOLVED: To effectively reduce a reversed crown generation at the time of hot rolling of a steel plate of which the material composition is such as to form, in a hot temperature range, a two phase area (α+γ) and anαhaploid phase by decarbonization, by forming a decarbonized layer having a larger dimension than the specified one on the side edge of the slab before heating. SOLUTION: The steel slab, of which material composition is such as to form, in a hot rolling temperature range, the two phase area (α+γ) and theαhaploid phase by decarbonization, is first heated to the temperature higher than 1,000 deg.C, then is performed by the hot roughing down and finishing hot rolling processes. A decarbonized layer having a thickness of 0.2 mm or more is formed at the side edge of the slab before heating. The reason to limit the heating temperature higher than 1,000 deg.C is that it is indispensable to keep the temperature higher than 1,000 deg.C to conduct an excellent finishing hot rolling of the material. Further, though the upper limit of the thickness of the decarbonized layers is not limited, if it exceeds 10 mm, not only a longer time is required for rolling but also there could be more crops. Therefore it is preferable to make it, about 10 mm or less.
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