Title:
SEAMLESS STEEL PIPE AND METHOD FOR MANUFACTURING SAME
Document Type and Number:
WIPO Patent Application WO/2022/038956
Kind Code:
A1
Abstract:
Provided are a seamless steel pipe and a method for manufacturing the same with which it is possible to improve fatigue life characteristics and suppress, even when performing cold working (cold drawing), occurrence of problems during the cold working, and thus improve the yield. In the seamless steel pipe according to the present invention, when Dout (mm) represents the outer diameter of the steel pipe and t (mm) represents the thickness thereof, t/Dout=0.05 to 0.40 is satisfied. In the seamless steel pipe, the maximum depth dmax (mm) of scratches in the steel pipe inner surface at the cross section perpendicular to the pipe axial direction is dmax ≤ 0.350 mm, the average depth dave (mm) of the scratches in a depth range of 0.050 mm or deeper in the steel pipe inner surface is dave ≤ 0.200 mm, and the number of the scratches per 1 mm of the inner circumferential length in the pipe circumferential direction, in a depth range of 0.050 mm or deeper in the steel pipe inner surface, is 30 or less.
Inventors:
SASAKI SHUNSUKE (JP)
TACHI RYOSUKE (JP)
YAMASAKI HIROYUKI (JP)
FUKUDA HIROYUKI (JP)
TACHI RYOSUKE (JP)
YAMASAKI HIROYUKI (JP)
FUKUDA HIROYUKI (JP)
Application Number:
PCT/JP2021/027349
Publication Date:
February 24, 2022
Filing Date:
July 21, 2021
Export Citation:
Assignee:
JFE STEEL CORP (JP)
International Classes:
B21B19/10; C21D8/10; C21D9/08; C22C38/00; C22C38/04; C22C38/54
Foreign References:
| JP2016196040A | 2016-11-24 | |||
| JP2007125588A | 2007-05-24 | |||
| JPH0957329A | 1997-03-04 | |||
| JP3082665B2 | 2000-08-28 | |||
| JP3463617B2 | 2003-11-05 |
Attorney, Agent or Firm:
KUMASAKA Akira et al. (JP)
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