Welded steel pipe having excellent hydroformability and method for making the same
US6682829B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 31, 2002 |
| Grant date | Jan 27, 2004 |
| Priority date | — |
| Expiry date | May 31, 2022 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/12965
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A welded steel pipe is formed by heating or soaking an untreated welded steel pipe having a steel composition comprising, on the basis of mass percent: about 0.05% to about 0.3% C; about 2.0% or less of Si; more than about 1.5% to about 5.0% Mn; about 0.1% or less of P; about 0.01% or less of S; about 0.1% or less of Cr; about 0.1% or less of Al; about 0.1% or less of Nb; about 0.3% or less of Ti; and about 0.01% or less of N; and by diameter-reduction-rolling the treated steel pipe at a accumulated diameter reduction rate of at least about 35% and a finish rolling temperature of about 500° C. to about 900° C. The welded steel pipe exhibits excellent hydroformability, i.e., has a tensile strength of about 780 MPa or more and a n×r product of at least about 0.15. The treated steel pipe is preferably diameter-reduction-rolled at a accumulated diameter reduction rate of at least about 20% below the Ar3 transformation point.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.