High-strength steel sheet and manufacturing method therefor
US11208709B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 21, 2018 |
| Grant date | Dec 28, 2021 |
| Priority date | — |
| Expiry date | Sep 12, 2038 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC21D2211/008
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Provided are a high-strength steel sheet having a yield strength of 550 MPa or higher and having a small amount of springback and width-direction uniformity in material properties as well as a manufacturing method therefor.The high-strength steel sheet has a yield strength (YP) of 550 MPa or higher and has a specific component composition and a microstructure containing a ferrite phase, 40 to 70% of a martensite phase in area ratio, and 5 to 30% of a bainite phase in area ratio, where: an average grain size of the martensite phase is 2 to 8 μm and an average grain size of the ferrite phase is 11 μm or less on a cross-section in the thickness direction and in a direction orthogonal to a rolling direction; and the average grain size of the ferrite phase is 3.0 times or less the average grain size of martensite.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.