High-yield-ratio, high-strength cold rolled steel sheet and production method therefor
US10156005B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 18, 2014 |
| Grant date | Dec 18, 2018 |
| Priority date | — |
| Expiry date | Apr 22, 2035 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC21D2211/008
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A steel sheet includes a microstructure containing a volume fraction of 20% to 55% of ferrite having an average grain size of 7 μm or less, a volume fraction of 5% to 15% of retained austenite, a volume fraction of 0.5% to 7% of martensite having an average grain size of 4 μm or less, and a structure composed of bainite and/or tempered martensite and having an average grain size of 6 μm or less, and a difference in nano-hardness between ferrite and the structure composed of bainite and/or tempered martensite being 3.5 GPa or less and a difference in nano-hardness between the structure composed of bainite and/or tempered martensite and martensite being 2.5 GPa or less.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.