High strength line pipe steel having low yield ratio and excellent in low temperature toughness
US5755895A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 10, 1996 |
| Grant date | May 26, 1998 |
| Priority date | — |
| Expiry date | Oct 10, 2016 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S148/909
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
An ultra-high strength low yield ratio line pipe steel has an excellent HAZ toughness and field weldability and has a tensile strength of at least 950 MPa (exceeding X100 of the API standard). The steel is of a low carbon-high Mn-Ni-Mo-Nb-trace Ti type selectively containing B, Cu, Cr and V, whenever necessary. Its micro-structure comprises a martensite/bainite and ferrite soft/hard two-phase mixed structure having a ferrite fraction of 20 to 90%. This ferrite contains 50 to 1000 of worked ferrite, and the ferrite grain size is not greater than 5 Am. The production of an ultra-high strength low yield ratio line pipe steel (exceeding X100) excellent in low temperature toughness and field weldability becomes possible. As a result, the safety of a pipeline can be remarkably improved, and execution efficiency and transportation efficiency of the pipeline can be drastically improved.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.