High-strength steel sheet having excellent room-temperature formability and warm formability, and warm forming method thereof
US9657381B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 15, 2012 |
| Grant date | May 23, 2017 |
| Priority date | — |
| Expiry date | May 21, 2034 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC21D2211/008
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
This high-strength steel plate has a component composition including, by mass %, C: 0.02-0.3%, Si: 1-3%, Mn: 1.8-3%, P: 0.1% or less, S: 0.01% or less, Al: 0.001-0.1%, N: 0.002-0.03%, the rest consisting of iron and impurities. Said steel plate has a microstructure including, in terms of area ratio relative to the entire microstructure, each of the following phases: bainitic ferrite: 50-85%; retained γ: 3% or greater; martensite+the aforementioned retained γ: 10-45%; and ferrite: 5-40%. The C concentration (CγR) in the aforementioned retained austenite is 0.3-1.2 mass %, part or all of the N in the aforementioned component composition is solid solution N, and the amount of said solid solution N is 30-100 ppm.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.