Welded steel pipe for linepipe with high compressive strength and manufacturing method thereof
US9089919B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 25, 2010 |
| Grant date | Jul 28, 2015 |
| Priority date | — |
| Expiry date | Jun 20, 2031 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC21D2211/002
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Provided are a steel pipe for a linepipe with high compressive strength and a heavy wall thickness, and a method of manufacturing the same. Lowering of yield stress caused by a Bauschinger effect can be suppressed by optimizing the metal microstructure of a steel plate without requiring particular forming conditions in forming the steel pipe, and without requiring heat treatment after pipe making. A steel pipe has the composition which contains by mass % 0.03 to 0.10% C, 0.30% or less Si, 1.00 to 2.00% Mn, 0.015% or less P, 0.003% or less S, 0.080% or less Al, 0.005 to 0.035% Nb, 0.005 to 0.020% Ti, and Fe and unavoidable impurities as a balance. The steel pipe has metal microstructure where a fraction of bainite is 60% or more, a fraction of rolled ferrite is 5% or less, and a fraction of M-A constituent (MA) is 3% or less.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.