High-strength steel sheet with excellent deep drawability at room temperature and warm temperature, and method for warm working same
US9194032B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 27, 2012 |
| Grant date | Nov 24, 2015 |
| Priority date | — |
| Expiry date | Nov 29, 2032 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC21D2211/008
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
This high-strength steel sheet has a component composition containing, in mass %, 0.02 to 0.3% C, 1 to 3% Si, 1.8 to 3% Mn, 0.1% or less P, 0.01% or less S, 0.001 to 0.1% Al, and 0.002 to 0.03% N, the remainder being iron and impurities. The high-strength steel sheet has a structure containing, in terms of area ratio relative to the entire structure, each of the following phases: 50 to 85% bainitic ferrite; 3% or more retained austenite (γ); 10 to 45% martensite and the aforementioned retained austenite (γ); and 5 to 40% ferrite. The ratio between the Mn concentration (MnγR) in the retained austenite (γ) and the average Mn concentration (Mnav) in the entire structure is 1.2 or more (MnγR/ Mnav) based on the Mn concentration distribution obtained by means of EPMA line analysis. As a consequence, the high-strength steel sheet exhibits strength of 980 MPa or more and exerts excellent deep drawability.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.