Super-high-strength line pipe excellent in low temperature toughness and production method thereof
US6532995B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 6, 2000 |
| Grant date | Mar 18, 2003 |
| Priority date | — |
| Expiry date | Jan 6, 2020 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T29/18
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
To provide a super-high strength line pipe that is excellent in low temperature toughness, can be field welded easily, and has a tensile strength of at least 900 MPa (exceeding ×100 of the API standard), and a production method thereof. The present invention relates to a super-high strength line pipe produced by shaping a steel plate into a pipe shape and arc welding seam portions, the strength of a base steel portion is 900 to 1,100 MPa and the strength of the weld metal is higher than the base steel strength −100 MPa. In the steel pipe, the Ni content of the weld metal is higher by at least 1% than that of the base steel. The combination of the chemical components of the steel plate with those of the weld metal, for accomplishing these steel pipes by a U&O step is shown concretely. A production method of the steel plate and the welding method for achieving the steel pipe are also described. Furthermore, a method of reducing the strength of the inner surface of the weld metal to restrict cracking at the time of pipe expansion is also shown.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.