Steel sheet
AssigneeNippon Steel Corporation
InventorsMasaharu OKA, Kazuo HIKIDA, Yuta DAIROKUNO
Life of this patent
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Abstract
A steel sheet of the present disclosure has a chemical composition containing, in mass %, C: 0.040 to 0.070%, Si: more than 0 to 0.10%, Mn: 0.20 to 0.40%, P: more than 0 to 0.030%, S: more than 0 to 0.030%, sol. Al: 0.005 to 0.100%, N: more than 0% to 0.0150%, and B: 0.0001 to 0.0030%. In the steel sheet, ferrite is the main phase, a grain size number is 11.0 or more, a sheet thickness is 0.15 to 1.00 mm, and at room temperature, the yield strength is 220 to 500 MPa, the tensile strength is 330 to 550 MPa, and the total elongation is 20.0% or more. An aging index AI is 50.0 MPa or more. A ratio of the tensile strength at 300° C. to the tensile strength at room temperature is 0.90 or more.
Claims4
A steel sheet that has a chemical composition consisting of, in mass %,
- C:
- 0.040 to 0.070%,
- Si:
- more than 0 to 0.10%,
- Mn:
- 0.20 to 0.40%,
- P:
- more than 0 to 0.030%,
- S:
- more than 0 to 0.030%,
- sol. Al:
- 0.005 to 0.100%,
- N:
- more than 0% to 0.0150%,
- B:
- 0.0001 to 0.0030%,
- Ti:
- 0 to 0.010%,
- Nb:
- 0 to 0.010%,
- Cu:
- 0 to 0.5%,
- Ni:
- 0 to 0.5%,
- Cr:
- 0 to 0.3%, and
- Sn:
- 0 to 0.05%,
- with the balance being Fe and impurities, and
- has a microstructure in which ferrite is a main phase and a grain size number of the ferrite is 11.0 or more, wherein
- the steel sheet has a sheet thickness that is 0.15 to 1.00 mm;
- the steel sheet has a yield strength that is 220 to 500 MPa at room temperature, a tensile strength that is 330 to 550 MPa at room temperature, and a total elongation that is 20.0% or more at room temperature;
- the steel sheet has an aging index AI that is 50.0 MPa or more;
- and
- a ratio of a tensile strength of the steel sheet at 300° C. to the tensile strength at room temperature is 0.90 or more.
Dependencies are inferred from the claim text.