High-strength steel sheet and high-strength steel pipe excellent in deformability and method for producing the same
US8070887B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 9, 2003 |
| Grant date | Dec 6, 2011 |
| Priority date | — |
| Expiry date | Oct 3, 2024 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC21D2211/005
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
The present invention provides a line pipe of, e.g., the API standard X60 to X100 class. The line pipe has an excellent deformability, as well as excellent low temperature toughness and high productivity, a steel plate used as the material of the steel pipe. Methods for producing the steel pipe and the steel plate are also provided. In particular, a high-strength steel plate excellent in the deformability has a ferrite phase is dispersed finely, and accounts for 5% to 40% in area percentage in a low temperature transformation structure mainly composed of a bainite phase. For example, most grain sizes of the ferrite phase are smaller than the average grain size of the bainite phase. A high-strength steel pipe excellent in deformability is also provided, in which a large diameter steel pipe is produced through forming the steel plate into a pipe shape. The steel pipe has the above-referenced structure, and satisfies the conditions that YS/TS is 0.95 or less and YS×uEL is 5,000 or more. Methods for producing such steel plate and steel pipe are also provided.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.