| 摘要 |
A continuous cast slab includes the following component: by mass %, C: 0.01˜0.3%, Si: 0.05˜0.5%, Mn: 0.4˜2%, P: 0.03% or less, S: 0.03 or less, Al: 0.005˜0.03%, Ni: 0.2˜2%, O: 0.006% or less, and N: 0.006% or less; wherein the balance is composed of Fe and inevitable impurities; wherein a structure in steel in a region within at least 2 mm from a broad surface is composed of ferrite and pearlite and a equivalent circular diameter of ferrite grains in the region is equal to or shorter than 30 μm.
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