Title:
HIGH-STRENGTH HOT-ROLLED STEEL SHEET FOR ELECTRIC RESISTANCE WELDED STEEL PIPE, AND METHOD FOR MANUFACTURING SAME
Document Type and Number:
WIPO Patent Application WO/2017/130875
Kind Code:
A1
Abstract:
Provided are a high-strength hot-rolled steel sheet for an electric-resistance-welded steel pipe having high strength, excellent ductility, and minimal variation in material quality in the plane of the sheet, and method for manufacturing the same. A high-strength hot-rolled steel sheet for an electric-resistance-welded steel pipe, having: a composition containing, in terms of mass%, 0.10-0.18% C, 0.1-0.5% Si, 0.8-2.0% Mn, 0.001-0.020% P, 0.005% or less of S, 0.001-0.1% Al, 0.4-1.0% Cr, 0.1-0.5% Cu, 0.01-0.4% Ni, 0.01-0.07% Nb, and 0.008% or less of N, further including 0.5% or less of Mo and/or 0.1% or less of V, and containing the above composition so that Moeq defined by the expression Moeq = Mo + 0.36Cr + 0.77Mn + 0.07Ni is 1.4-2.2, and Mo and V satisfy the expression 0.05 ≤ Mo + V ≤ 0.5; and a metallographic structure having a bainite phase as a volume fraction of 80% or greater as the main phase and containing a martensite phase and a residual austenite phase as second phases as a combined volume fraction of 4-20%, the average crystal grain size of the bainite phase being 1-10 µm.
Inventors:
NAKATA HIROSHI (JP)
URABE MOTOHIKO (JP)
KAWAMURA SHUJI (JP)
URABE MOTOHIKO (JP)
KAWAMURA SHUJI (JP)
Application Number:
PCT/JP2017/002041
Publication Date:
August 03, 2017
Filing Date:
January 23, 2017
Export Citation:
Assignee:
JFE STEEL CORP (JP)
International Classes:
C22C38/00; C21D8/02; C21D9/46; C22C38/58
Domestic Patent References:
| WO2013108861A1 | 2013-07-25 | |||
| WO2014041802A1 | 2014-03-20 |
Foreign References:
| JPH1150188A | 1999-02-23 | |||
| JP2009270142A | 2009-11-19 |
Other References:
See also references of EP 3409803A4
Attorney, Agent or Firm:
KUMASAKA Akira et al. (JP)
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