High-strength cold-rolled steel sheet and method for producing the same
US9090952B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 24, 2010 |
| Grant date | Jul 28, 2015 |
| Priority date | — |
| Expiry date | Nov 1, 2031 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC23G1/081
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A high-strength cold-rolled steel sheet having high chemical convertibility and a tensile strength of 590 MPa or more and a method for producing such a steel sheet are provided. The steel sheet contains, in terms of percent by mass, C: 0.05 to 0.3%, Si: 0.6 to 3.0%, Mn: 1.0 to 3.0%, P: 0.1% or less, S: 0.05% or less, Al: 0.01 to 1%, N: 0.01% or less, and the balance being Fe and unavoidable impurities. The coverage ratio of reduced iron on a steel sheet surface is 40% or more. In order to produce such a steel sheet, an oxidation treatment is performed after cold rolling. Subsequently, annealing is conducted in a furnace in a 1 to 10 vol % H2+balance N2 gas atmosphere with a dew point of −25° C. or less.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.