Continuous cast slab and producing method therefor
AssigneeNippon Steel & Sumitomo Metal Corporation
InventorsAkihito Kiyose, Toshiyuki Kajitani, Mineo Niizuma, Yasuhiko Otani
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Abstract
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.
Claims4
A continuous cast steel slab comprising, 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,
- N:
- 0.006% or less;
- and
- a balance of Fe and inevitable impurities;
- wherein a structure in the steel in a region within at least a depth of 2 mm from a broad surface of the slab is composed of ferrite and pearlite, and an equivalent circular diameter of ferrite grains in the region is equal to or shorter than 30 μm.
A method for producing a continuous cast steel slab, the method comprising:
- casting continuously a molten steel comprising 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,
- N:
- 0.006% or less, and
- a balance of Fe and inevitable impurities,
- using a vertical-bending or a bow continuous casting machine;
- cooling down a surface of the cast steel slab to 550° C. or lower between a mold outlet and a straightening zone of the vertical-bending or the bow continuous casting machine;
- and
- thereafter reheating between the mold outlet and the straightening zone of the vertical-bending or the bow continuous casting machine to 850° C. or higher to straighten the cast steel slab.
Dependencies are inferred from the claim text.