Title:
HIGH-STRENGTH SEAMLESS STEEL PIPE FOR OIL WELL AND METHOD FOR PRODUCING SAME
Document Type and Number:
WIPO Patent Application WO/2018/074109
Kind Code:
A1
Abstract:
Provided is a high-strength seamless steel pipe for oil wells that has excellent sulfide stress corrosion cracking resistance, wherein: the composition is, in mass%,0.20 to 0.50% C, 0.05 to 0.40% Si, 0.3 to 0.9% Mn, at most 0.015% P, at most 0.005% S, 0.03 to 0.1% Al, at most 0.006% N, greater than 0.6% to at most 1.7% Cr, greater than 1.0% to at most 3.0% Mo, 0.02 to 0.3% V, 0.001 to 0.02% Nb, 0.0005 to 0.0040% B, at most 0.0030% O, and less than 0.003% Ti; the volume percentage of tempered martensite is at least 90%; and, in a cross section perpendicular to the rolling direction, the number of nitride-based inclusions with particle sizes of at least 4 µm is at most 50 per 100 mm2 and the number of inclusions with particle sizes of smaller than 4 µm is at most 500 per 100 mm2, and the number of oxide-based inclusions with particle sizes of at least 4 µm is at most 40 per 100 mm2 and the number of inclusions with particle sizes of smaller than 4 µm is at most 400 per 100 mm2.
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Inventors:
YUGA MASAO (JP)
OKATSU MITSUHIRO (JP)
OKATSU MITSUHIRO (JP)
Application Number:
PCT/JP2017/033007
Publication Date:
April 26, 2018
Filing Date:
September 13, 2017
Export Citation:
Assignee:
JFE STEEL CORP (JP)
International Classes:
C22C38/00; C21D8/10; C21D9/08; C22C38/32; C22C38/54
Domestic Patent References:
| WO2016038810A1 | 2016-03-17 | |||
| WO2016079908A1 | 2016-05-26 | |||
| WO2016103537A1 | 2016-06-30 | |||
| WO2016103538A1 | 2016-06-30 | |||
| WO2016093161A1 | 2016-06-16 | |||
| WO2015011917A1 | 2015-01-29 | |||
| WO2016079908A1 | 2016-05-26 |
Foreign References:
| US20160184875A1 | 2016-06-30 | |||
| JP2000178682A | 2000-06-27 | |||
| JP2000297344A | 2000-10-24 | |||
| JP2001172739A | 2001-06-26 | |||
| JP2007016291A | 2007-01-25 | |||
| JPS5930140B2 | 1984-07-25 |
Other References:
See also references of EP 3527684A4
Attorney, Agent or Firm:
KUMASAKA Akira et al. (JP)
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