Cold-rolled steel sheet and galvannealed steel sheet
US9340860B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 4, 2009 |
| Grant date | May 17, 2016 |
| Priority date | — |
| Expiry date | Feb 8, 2032 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC23C2/29
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A high strength cold-rolled steel sheet and a high strength plated steel sheet which have an excellent surface appearance required for outer panels of automobiles and which have an extremely high r value in a direction at 45° with respect to the rolling direction and which have excellent press formability and a tensile strength of at least 340 MPa and a process for their manufacture are provided. The steel sheets have a chemical composition consisting essentially of, in mass %, C: 0.0005-0.025%, Si: at most 0.2%, Mn: 0.3-2.5%, P: at most 0.15%, S: at most 0.02%, N: at most 0.006%, sol. Al: less than 0.005%, Ti: 0.005-0.05%, and Nb: 0.020-0.200% with the mass ratio (Nb/Ti) of the contents of Nb and Ti being at least 2, and a remainder of Fe and impurities, and they have an r value in a direction at 45° with respect to the rolling direction (r45) of at least 1.80 and/or a mean r value (rm) of at least 1.60, and a tensile strength of at least 340 MPa.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.