Title:
HIGH-STRENGTH STEEL SHEET FOR SOUR-RESISTANT LINE PIPE AND METHOD FOR MANUFACTURING SAME, AND HIGH-STRENGTH STEEL PIPE USING HIGH-STRENGTH STEEL SHEET FOR SOUR-RESISTANT LINE PIPE
Document Type and Number:
WIPO Patent Application WO/2023/248638
Kind Code:
A1
Abstract:
The present invention provides a high-strength steel sheet that is for a sour-resistant line pipe and that has not only excellent HIC resistance and SSCC resistance but also excellent low temperature toughness. A high-strength steel sheet for a sour-resistant line pipe according to the present invention has a component composition containing, in mass%, 0.030-0.060% of C, 0.01-0.50% of Si, 0.80-1.80% of Mn, 0.015% or less of P, 0.0015% or less of S, 0.010-0.080% of Al, 0.05-0.50% of Cr, 0.005-0.080% of Nb, 0.0010-0.0080% of N, and 0.0005-0.0050% of Ca, the remaining portion being Fe and unavoidable impurities. The steel structure at 0.25 mm below the surface of the steel sheet includes granular bainite and tempered island martensite. At the center in the sheet thickness, the maximum crystal grain size is 80 μm or less and the average crystal grain size is 20 μm or less. The ductile-brittle transition temperature of the steel sheet in a Charpy impact test is -100℃ or lower. The steel sheet has a tensile strength of 535 MPa or more.
Inventors:
IZUMI DAICHI (JP)
TAMURA YUTA (JP)
SHIMAMURA JUNJI (JP)
SHIBAMOTO YUHEI (JP)
YAMANE TAKESHI (JP)
TAMURA YUTA (JP)
SHIMAMURA JUNJI (JP)
SHIBAMOTO YUHEI (JP)
YAMANE TAKESHI (JP)
Application Number:
PCT/JP2023/017639
Publication Date:
December 28, 2023
Filing Date:
May 10, 2023
Export Citation:
Assignee:
JFE STEEL CORP (JP)
International Classes:
C22C38/00; B21B3/00; B21C37/08; C21D8/02; C22C38/38; C22C38/58
Domestic Patent References:
| WO2020003499A1 | 2020-01-02 | |||
| WO2021020220A1 | 2021-02-04 | |||
| WO2020067209A1 | 2020-04-02 |
Attorney, Agent or Firm:
SUGIMURA Kenji (JP)
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