High strength thick welded steel pipe for line pipe superior in low temperature toughness and method of production of the same
US8084144B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 4, 2007 |
| Grant date | Dec 27, 2011 |
| Priority date | — |
| Expiry date | Dec 31, 2028 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/12972
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
The present invention provides high strength thick welded steel pipe for line pipe superior in low temperature toughness, and a method of production of the same. A base material steel plate containing C: 0.010 to 0.050%, Si: 0.01 to 0.50%, Mn: 0.50 to 2.00%, Al: 0.020% or less, Ti: 0.003 to 0.030%, and Mo: 0.10 to 1.50%, having a carbon equivalent Ceq of 0.30 to 0.53, having a crack susceptability parameter Pcm of 0.10 to 0.20, satisfying formula 3, comprised an area ratio of 20% or less of polygonal ferrite and an area ratio of 80% or more of bainite, and having an effective crystal grain size of 20 μm or less is formed into a pipe shape, then seam welded to make the effective crystal grain size of the heat affected zone 150 μm or less:10C+100Al+5Mo+5Ni<3.3 formula 3.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.