Title:
HIGH-STRENGTH SEAMLESS STEEL PIPE FOR OIL WELLS, AND PRODUCTION METHOD FOR HIGH-STRENGTH SEAMLESS STEEL PIPE FOR OIL WELLS
Document Type and Number:
WIPO Patent Application WO/2016/103537
Kind Code:
A1
Abstract:
Provided is a high-strength seamless steel pipe for oil wells that has excellent sulfide stress corrosion cracking resistance. The seamless steel pipe includes, by mass%, 0.20%-0.50% of C, 0.05%-0.40% of Si, 0.3%-0.9% Mn, 0.015% or less of P, 0.005% or less of S, 0.005%-0.1% of Al, 0.006% or less of N, more than 1.0% but 3.0% or less of Mo, 0.01% or more but less than 0.05% of V, 0.001% or more but less than 0.01% of Nb, 0.0003%-0.0030% of B, 0.0030% or less of O, and 0.003%-0.025% of Ti, wherein Ti/N is 2.0-5.0. The seamless steel pipe has a volume fraction of tempered martensite of 95% or higher, has a prior austenite grain size number of 8.5 or higher, and, within a cross-section that is orthogonal to the rolling direction, has, per 100 mm2, 100 or fewer nitride inclusions that have a grain size of 4 μm or more, 1000 or fewer nitride inclusions that have a grain size of less than 4 μm, 40 or fewer oxide inclusions that have a grain size of 4 μm or more, and 400 or fewer oxide inclusions that have a grain size of less than 4 μm.
Inventors:
YUGA MASAO (JP)
ISHIGURO YASUHIDE (JP)
NABESHIMA SEIJI (JP)
OKATSU MITSUHIRO (JP)
OTA HIROKI (JP)
ISHIGURO YASUHIDE (JP)
NABESHIMA SEIJI (JP)
OKATSU MITSUHIRO (JP)
OTA HIROKI (JP)
Application Number:
PCT/JP2015/004621
Publication Date:
June 30, 2016
Filing Date:
September 10, 2015
Export Citation:
Assignee:
JFE STEEL CORP (JP)
International Classes:
C22C38/00; C21D8/10; C21D9/08; C22C38/14; C22C38/54
Foreign References:
| JP2007016291A | 2007-01-25 | |||
| JP2001172739A | 2001-06-26 | |||
| JP2012519238A | 2012-08-23 | |||
| JP2006028612A | 2006-02-02 | |||
| JP2014129594A | 2014-07-10 |
Other References:
See also references of EP 3202942A4
Attorney, Agent or Firm:
KUMASAKA, Akira et al. (JP)
Akira Kumasaka (JP)
Akira Kumasaka (JP)
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