| US 7,591,914 B2 | ||
| High-workability steel pipe and method of producing same | ||
| Takaaki Toyooka, Handa (Japan); Yoshikazu Kawabata, Handa (Japan); Akira Yorifuji, Handa (Japan); Masanori Nishimori, Handa (Japan); Motoaki Itadani, Handa (Japan); Takatoshi Okabe, Handa (Japan); and Masatoshi Aratani, Handa (Japan) | ||
| Assigned to JFE Steel Corporation, (Japan) | ||
| Appl. No. 10/258,982 PCT Filed Jun. 14, 2001, PCT No. PCT/JP01/05053 § 371(c)(1), (2), (4) Date Oct. 30, 2002, PCT Pub. No. WO02/103069, PCT Pub. Date Dec. 27, 2002. |
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| Prior Publication US 2003/0145913 A1, Aug. 07, 2003 | ||
| Int. Cl. C21D 9/08 (2006.01); C22C 38/00 (2006.01) | ||
| U.S. Cl. 148—519 [148/320] | 12 Claims |
| 1. A method of producing a high-workability steel pipe comprising:
seam-welding strip steel into a steel pipe;
heating the steel pipe to temperatures of more than Ac3; and
immediately or after cooling and reheating said steel pipe, performing diameter-reducing rolling of the steel pipe in a temperature
range of from 700° C. to Ac3 with a reduction in diameter of the steel pipe of not less than 30% such that the pipe and a weld in the pipe have an r-value
of 1.3 or more.
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