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Title:
SEAMLESS STEEL PIPE AND METHOD FOR PRODUCING SAME
Document Type and Number:
WIPO Patent Application WO/2017/200033
Kind Code:
A1
Abstract:
Provided is a seamless steel pipe which has excellent SSC resistance, while being suppressed in strength variation in the circumferential direction and in the axial direction. A seamless steel pipe according to one embodiment of the present invention contains, in mass%, 0.21-0.35% of C, 0.10-0.50% of Si, 0.05-1.00% of Mn, 0.025% or less of P, 0.010% or less of S, 0.005-0.100% of Al, 0.010% or less of N, 0.05-1.50% of Cr, 0.10-1.50% of Mo, 0.010-0.050% of Nb, 0.0003-0.0050% of B and 0.002-0.050% of Ti, with the balance made up of Fe and impurities. With respect to the main body region of this seamless steel pipe, the crystal grain size number of prior austenite crystal grains in accordance with ASTM E112 is 7.0 or more; the difference between the maximum value and the minimum value of the crystal grain size number is 1.0 or less; the yield strength is 655 MPa or more but less than 862 MPa; and the difference between the maximum value and the minimum value of the tensile strength is 27.6 MPa or less.

Inventors:
SOMA, Atsushi (6-1 Marunouchi 2-chome, Chiyoda-k, Tokyo 71, 〒1008071, JP)
ARAI, Yuji (6-1 Marunouchi 2-chome, Chiyoda-k, Tokyo 71, 〒1008071, JP)
TATEBAYASHI, Yosuke (6-1 Marunouchi 2-chome, Chiyoda-k, Tokyo 71, 〒1008071, JP)
FURO, Keisuke (6-1 Marunouchi 2-chome, Chiyoda-k, Tokyo 71, 〒1008071, JP)
KURAMOTO, Takenori (6-1 Marunouchi 2-chome, Chiyoda-k, Tokyo 71, 〒1008071, JP)
KAMITANI, Hiroki (6-1 Marunouchi 2-chome, Chiyoda-k, Tokyo 71, 〒1008071, JP)
YAMANE, Kouji (6-1 Marunouchi 2-chome, Chiyoda-k, Tokyo 71, 〒1008071, JP)
Application Number:
JP2017/018618
Publication Date:
November 23, 2017
Filing Date:
May 18, 2017
Export Citation:
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Assignee:
NIPPON STEEL & SUMITOMO METAL CORPORATION (6-1 Marunouchi 2-chome, Chiyoda-ku Tokyo, 71, 〒1008071, JP)
International Classes:
C22C38/00; B21B19/04; C21D8/10; C21D9/08; C22C38/32
Domestic Patent References:
2016-04-21
2016-03-17
2015-12-17
2013-06-27
2013-02-28
Foreign References:
JP2015038247A2015-02-26
JP2014129594A2014-07-10
JP2014012890A2014-01-23
JP2011246798A2011-12-08
JP2007031756A2007-02-08
Attorney, Agent or Firm:
ASCEND IP LAW FIRM (5-17, Dojima 1-chome Kita-ku, Osaka-sh, Osaka 03, 〒5300003, JP)
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