High tensile strength steel sheet excellent in processibility and process for manufacturing the same
US7455736B2 · kind B2 · utility
Assignees
Inventors
Key dates
| Filing date | Aug 30, 2004 |
| Grant date | Nov 25, 2008 |
| Priority date | — |
| Expiry date | Jan 2, 2026 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/12799
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A high tensile strength steel sheet excellent in processibility which can satisfy a strength, a total elongation, and stretch-flanging property (hole enlarging rate) at a further high level. and comprises a matrix microstructure of tempered martensite or tempered bainite and, if necessary, ferrite, and a second phase of retained austenite, wherein (1) the steel comprising C: 0.10 to 0.6 mass %, Si: 1.0 mass % or smaller, Mn: 1.0 to 3 ,mass %, Al: 0.3 to 2.0 mass %, P: 0.02 mass % or smaller, S: 0.03 mass % or smaller, (2) a volume rate of retained austenite obtained by a saturated magnetization measuring method is 5 to 40% by area (whole field is 100%), and (3) a relationship of a carbon amount (C: weight %) in the steel, a volume rate (fγR) of retained austenite and a carbon concentration (CγR) of the retained austenite satisfies the equation:(fγR×CγR)/C≧50 . (I)
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.