Title:
HIGH-STRENGTH STAINLESS STEEL SEAMLESS PIPE FOR OIL WELLS
Document Type and Number:
WIPO Patent Application WO/2021/131445
Kind Code:
A1
Abstract:
The purpose of the present invention is to provide a high-strength stainless steel seamless pipe for oil wells, said high-strength stainless steel seamless pipe having excellent carbon dioxide gas corrosion resistance and excellent SSC resistance in a low temperature environment, while having high strength and excellent hot formability. A high-strength stainless steel seamless pipe for oil wells, said high-strength stainless steel seamless pipe having a composition that contains a specific component composition with the balance being made up of Fe and unavoidable impurities, while satisfying formula (1) and formula (2). With respect to this high-strength stainless steel seamless pipe for oil wells, the number density of inclusions having a length of 5 μm or more and satisfying 0.5 < Ti/(Ti + Al + Mg + Ca) < 1.0 is from 0.5 per mm2 to 3 per mm2, and the yield strength is 655 MPa or more. (Meanwhile, Ti, Al, Mg and Ca in 0.5 < Ti/(Ti + Al + Mg + Ca) < 1.0 represent the respective contents (mass%) of the elements in the inclusions, while representing zero in cases where the corresponding element is not contained therein.) Formula (1): Cr + 0.65Ni + 0.6Mo + 0.55Cu - 20C ≥ 15.0
Formula (2): Cr + Mo + 0.3Si - 43.3C - 0.4Mn – Ni - 0.3Cu - 9N ≤ 11.0
In the formulae, Cr, Ni, Mo, Cu, C, Si, Mn and N represent the respective contents (mass%) of the elements, while representing zero in cases where the corresponding element is not contained therein.
Inventors:
EGUCHI KENICHIRO (JP)
MURAI TAKESHI (JP)
ENDO MAMI (JP)
YUGA MASAO (JP)
MURAI TAKESHI (JP)
ENDO MAMI (JP)
YUGA MASAO (JP)
Application Number:
PCT/JP2020/043310
Publication Date:
July 01, 2021
Filing Date:
November 20, 2020
Export Citation:
Assignee:
JFE STEEL CORP (JP)
International Classes:
C21D9/08; C22C38/00; C22C38/58; C21D8/10
Domestic Patent References:
| WO2019065114A1 | 2019-04-04 | |||
| WO2018181404A1 | 2018-10-04 | |||
| WO2019225280A1 | 2019-11-28 | |||
| WO2019225281A1 | 2019-11-28 |
Foreign References:
| JP2001131698A | 2001-05-15 |
Other References:
See also references of EP 4043591A4
Attorney, Agent or Firm:
KUMASAKA Akira et al. (JP)
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