High-strength steel sheet and method for producing the same
US11111553B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 7, 2017 |
| Grant date | Sep 7, 2021 |
| Priority date | — |
| Expiry date | Mar 3, 2038 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC21D2211/008
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A high-strength steel sheet having a tensile strength (TS) of 1,320 MPa or more and good workability. The high-strength steel sheet has a specific component composition and a steel microstructure containing, on an area-percentage basis with respect to the entire steel microstructure, 40% or more and less than 85% of a lower bainite, 5% or more and less than 40% martensite including tempered martensite, 10% or more and 30% or less retained austenite, and 10% or less (including 0%) polygonal ferrite, the retained austenite having an average C content of 0.60% by mass or more. Additionally, a Mn segregation value at a surface of the steel sheet is 0.8% or less, the ratio R/t of a limit bending radius (R) to a thickness (t) of the steel sheet is 2.0 or less, and tensile strength×total elongation of the steel sheet is 15,000 MPa % or more.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.