Welded steel pipe having excellent hydroformability and method for making the same
US6749954B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 31, 2002 |
| Grant date | Jun 15, 2004 |
| Priority date | — |
| Expiry date | May 31, 2022 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/12965
- WIPO fieldMachine tools
- WIPO sectorMechanical engineering
Abstract
A welded steel pipe is formed by heating or soaking an untreated welded steel pipe having a steel composition containing, on the basis of mass percent: about 0.03% to about 0.2% C, about 2.0% or less of Si, not less than about 1.0% to about 1.5% Mn, about 0.1% or less of P, about 0.01% or less of S, about 1.0% or less of Cr, about 0.1% or less of Al, about 0.1% or less of Nb, about 0.1% or less of Ti, about 0.1% or less of V, and about 0.01% or less of N; and by reduction-rolling the treated steel pipe at a cumulative reduction rate of at least about 35% and a final rolling temperature of about 500° C. to about 900° C. The welded steel pipe exhibits excellent hydroformability, i.e., has a tensile strength of at least about 590 MPa and an n×r product of at least about 0.22. The treated steel pipe is preferably reduction-rolled at a cumulative reduction rate of at least about 20% below the Ar3 transformation point.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.