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US 2026/0265883 A1Published application
Steel sheet
AssigneeNippon Steel Corporation
InventorsKoyo OHGA, Kengo TAKEDA, Satoshi HIRONAKA
Life of this patent
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Abstract
Provided is a steel sheet having a predetermined chemical composition, wherein an average Vickers hardness Hs in a region from at least one surface down to 10% of sheet thickness is 0.60 time or less an average Vickers hardness Hc at a ½ position of sheet thickness, a ratio of macro brittle fracture surface in a Charpy impact test at room temperature is 35.0% or less, and a tensile strength is 1500 MPa or more.
Claims21
1-6. (canceled)
A steel sheet having a chemical composition comprising, by mass %,
- C:
- 0.15 to 0.40%,
- Si:
- 0.01 to 2.00%,
- Mn:
- 0.80 to 3.50%,
- P:
- 0.0001 to 0.0200%,
- S:
- 0.0001 to 0.0200%,
- Al:
- 0.001 to 1.000%,
- N:
- 0.0001 to 0.020%,
- O:
- 0.0001 to 0.0200%,
- Co:
- 0 to 0.5000%,
- Ni:
- 0 to 1.000%,
- Mo:
- 0 to 1.000%,
- Cr:
- 0 to 2.000%,
- Ti:
- 0 to 0.500%,
- B:
- 0 to 0.0100%,
- Nb:
- 0 to 0.500%,
- V:
- 0 to 0.500%,
- Cu:
- 0 to 0.500%,
- W:
- 0 to 0.100%,
- Ta:
- 0 to 0.100%,
- Sn:
- 0 to 0.100%,
- Sb:
- 0 to 0.100%,
- As:
- 0 to 0.100%,
- Mg:
- 0 to 0.0500%,
- Ca:
- 0 to 0.050%,
- Y:
- 0 to 0.050%,
- Zr:
- 0 to 0.050%,
- La:
- 0 to 0.050%,
- Ce:
- 0 to 0.050%, and
- balance:
- Fe and impurities, wherein
- an average Vickers hardness Hs in a region from at least one surface down to 10% of sheet thickness is 0.95 time or less an average Vickers hardness Hc at a ½ position of sheet thickness,
- a ratio of macro brittle fracture surface in a Charpy impact test at room temperature is 35.0% or less, and
- a tensile strength is 1500 MPa or more.
58 more elements
Dependencies are inferred from the claim text.