Steel plate and welded steel tube exhibiting low yield ratio, high strength and high toughness
US7520943B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 10, 2004 |
| Grant date | Apr 21, 2009 |
| Priority date | — |
| Expiry date | Feb 16, 2025 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC21D2211/008
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A low yield ratio, high toughness steel plate which can be manufactured at high manufacturing efficiency and low cost, without increasing material cost by adding large amount of alloy elements and the like, and without degrading toughness of a welding heat affected zone, a low yield ratio, high strength and high toughness steel pipe using the steel plate, and a method for manufacturing those are provided. Specifically, the steel plate and the steel pipe contain C of 0.03% to 0.1%, Si of 0.01 to 0.5%, Mn of 1.2 to 2.5% and Al of 0.08% or less, wherein a metal structure is a substantially three-phase structure of ferrite, bainite and island martensite, and an area fraction of the island martensite is 3 to 20%, in addition, a complex carbide is precipitated in the ferrite phase.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.