High-strength steel pipe excellent in formability and burst resistance
US6782921B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 26, 2002 |
| Grant date | Aug 31, 2004 |
| Priority date | — |
| Expiry date | Nov 26, 2022 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T29/18
- WIPO fieldMachine tools
- WIPO sectorMechanical engineering
Abstract
A high-strength steel pipe excellent in formability and burst resistance wherein, when a high-strength steel pipe exceeding 850 N/mm2 in tensile strength is produced by a UOE method, a ratio (R/r) of an average radius of curvature in a range of 120 mm in a circumferential direction including a weld of the steel pipe before pipe expansion in a pipe expansion process (R) to the radius of the steel pipe after pipe expansion (r) is 0.65 to 2.0, and preferably the ratio (R/r) is 0.90 to 2.0. Preferably, Vickers hardness of the base metal Hv, the minimum Vickers hardness at the HAZ Hz, pipe wall thickness t, and a peaking amount at the weld of the steel pipe before pipe expansion in a pipe expansion process &dgr; satisfy the following expression,(1+0.005t|&dgr;|)Hz<0.03584Hv2−25.34Hv+4712.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.