SEAMLESS STEEL PIPE AND METHOD FOR PRODUCING SAME - NIPPON STEEL & SUMITOMO METAL CORP

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 (JP)
ARAI YUJI (JP)
TATEBAYASHI YOSUKE (JP)
FURO KEISUKE (JP)
KURAMOTO TAKENORI (JP)
KAMITANI HIROKI (JP)
YAMANE KOUJI (JP)

Application Number:

PCT/JP2017/018618

Publication Date:

November 23, 2017

Filing Date:

May 18, 2017

Export Citation:

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Assignee:

NIPPON STEEL & SUMITOMO METAL CORP (JP)

International Classes:

C22C38/00; B21B19/04; C21D8/10; C21D9/08; C22C38/32

Domestic Patent References:

WO2016059763A1	2016-04-21
WO2016038810A1	2016-03-17
WO2015190377A1	2015-12-17
WO2013094179A1	2013-06-27
WO2013027666A1	2013-02-28

Foreign References:

JP2015038247A	2015-02-26
JP2014129594A	2014-07-10
JP2014012890A	2014-01-23
JP2011246798A	2011-12-08
JP2007031756A	2007-02-08

Other References: