High-strength steel sheet and method for manufacturing the same
US11739392B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 7, 2017 |
| Grant date | Aug 29, 2023 |
| Priority date | — |
| Expiry date | Nov 15, 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 1320 MPa or more and excellent workability. The high-strength steel sheet has a chemical composition containing, by mass %, C: 0.20% or more and 0.40% or less, Si: 0.5% or more and 2.5% or less, Mn: more than 2.4% and 5.0% or less, P: 0.1% or less, S: 0.01% or less, Al: 0.01% or more and 0.5% or less, N: 0.010% or less, and Fe and inevitable impurities. A microstructure of the steel sheet includes, in terms of area fraction with respect to the whole steel sheet microstructure, lower bainite in an amount of 40% or more and less than 85%, martensite including tempered martensite in an amount of 5% or more and less than 40%, retained austenite in an amount of 10% or more and 30% or less, and polygonal ferrite in an amount of 10% or less (including 0%).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.