High strength cold rolled steel sheet and method for manufacturing the same
US7608156B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 26, 2004 |
| Grant date | Oct 27, 2009 |
| Priority date | — |
| Expiry date | Jul 31, 2025 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC21D2211/005
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
This disclosure relates to a high strength cold rolled steel sheet composed of ferrite grains having an average grain diameter of 10 μm or less, in which the average number per unit area of Nb(C, N) precipitates having a diameter of 50 nm or more is 7.0×10−2/μm2 or less, and a zone having a width of 0.2 to 2.4 μm and an average area density of NbC precipitates of 60% or less of that of the central portion of the ferrite grains is formed along grain boundaries of the ferrite grains, for example, the steel sheet consisting of 0.004 to 0.02% of C, 1.5% or less of Si, 3% or less of Mn, 0.15% or less of P, 0.02% or less of S, 0.1 to 1.5% of sol.Al, 0.001 to 0.007% of N, 0.03 to 0.2% of Nb, by mass, and the balance of Fe and inevitable impurities. The steel sheet is most preferably used for automobile panel parts since it has the TS of 340 MPa or more and the superior surface strain resistance and press formability.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.