Title:
ラインパイプ用鋼管及びその製造方法
Document Type and Number:
Japanese Patent JP6394809
Kind Code:
B2
Abstract:
A steel pipe for line pipe with reduced hardness of a surface layer portion is provided. A steel pipe for line pipe has a chemical composition of, in mass%: C: 0.02 to 0.11 %; Si: 0.05 to 1.0 %; Mn: 0.30 to 2.5 %; P: up to 0.030 %; S: up to 0.006 %; Cr: 0.05 to 0.36 %; Mo: 0.02 to 0.33 %; V: 0.02 to 0.20 %; Ti: 0.001 to 0.010 %; Al: 0.001 to 0.100 %; N: up to 0.008 %; Ca: 0.0005 to 0.0040 %; and other elements, the chemical composition satisfying Equation (1) below, the steel pipe having a microstructure containing tempered martensite and/or tempered bainite and further containing ferrite in at least one of a portion between an outer surface of the steel pipe and a depth of 1 mm from the outer surface, and a portion between an inner surface of the steel pipe and a depth of 1 mm from the inner surface, Cr + Mo + V ¤ 0.40 wherein each of the chemical symbols in equation (1) is substituted for by the content of the corresponding element in mass%.
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Inventors:
Taro Oe
Keiichi Kondo
Yuki Kamiya
Yuji Arai
Keiichi Kondo
Yuki Kamiya
Yuji Arai
Application Number:
JP2017531088A
Publication Date:
September 26, 2018
Filing Date:
June 23, 2016
Export Citation:
Assignee:
Nippon Steel & Sumitomo Metal Corporation
International Classes:
C22C38/00; C21D9/08; C22C38/58
Domestic Patent References:
| JP2004176172A | ||||
| JP2012241274A | ||||
| JP2014218707A | ||||
| JP2004124158A | ||||
| JP2013129870A | ||||
| JP2009133005A |
Foreign References:
| WO2013161567A1 | ||||
| WO2013147197A1 | ||||
| WO2008123025A1 | ||||
| WO2013002418A1 |
Attorney, Agent or Firm:
Hidetoshi Ueba
Satoshi Komiyama
Satoshi Komiyama