Electric resistance welded steel pipe and manufacturing method therefor
US10584405B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 17, 2015 |
| Grant date | Mar 10, 2020 |
| Priority date | — |
| Expiry date | Sep 14, 2036 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC21D8/02
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A resistance welded steel pipe is provided. A hot-rolled steel sheet having a composition containing, in mass %, C: 0.025 to 0.168%, Si: 0.10 to 0.30%, Mn: 0.60 to 1.90%, and one or at least two selected from Ca, Nb, V, and Ti such that Pcm is 0.20 or less is subjected to continuous cold roll forming to obtain a pipe-shaped body. Tapered grooves are formed in the steel sheet such that the ratio of the tapered portions to the wall thickness of the steel sheet is 10 to 80%. Then end surfaces of the pipe-shaped body are butted against each other and subjected to electric resistance welding. Ultrasonic waves are transmitted toward the electric resistance weld surface such that a beam width is within the range of 0.1 to 4.0 mm, and the reflected waves are used for ultrasonic flaw detection using an ultrasonic flaw detector.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.