High-strength steel sheet and method for manufacturing the same
US11091817B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 29, 2017 |
| Grant date | Aug 17, 2021 |
| Priority date | — |
| Expiry date | Apr 30, 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 high strength of a yield strength of 550 MPa or more and a method for manufacturing the same.The high-strength steel sheet has a specified chemical composition and a microstructure, where observed in a cross section in a thickness direction perpendicular to a rolling direction, including a martensite phase having a volume fraction of 50% to 80%, and a ferrite phase having an average grain diameter of 13 μm or less, wherein a volume fraction of ferrite grains having an aspect ratio of 2.0 or less with respect to the whole ferrite phase is 70% or more, and wherein an average length in a longitudinal direction (in a width direction of the steel sheet) of the ferrite grains is 20 μm or less, and a yield strength (YP) of 550 MPa or more.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.