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Title:
STEEL FOR HIGH-STRENGTH BOLTS WHICH HAS EXCELLENT DELAYED FRACTURE RESISTANCE AND BOLT MOLDABILITY, AND BOLT
Document Type and Number:
WIPO Patent Application WO/2015/045951
Kind Code:
A1
Abstract:
Provided is a steel for high-strength bolts, which can exhibit satisfactory delayed fracture resistance even under a severe condition and has good bolt moldability. The steel for high-strength bolts according to the present invention has a properly controlled chemical composition in which 0.10 to 0.30% of C and 0.4 to 0.7% of Ni are contained, and meets requirements respectively expressed by the formulae (1) and (2): (1) 0.85 ≤ [C]+[Si]/7+[Mn]/5+[Ni]/20+[Cr]/9+[Mo]/2 ≤ 1.3; and (2) [C]-(0.07×[Mo]+0.20×[V]) ≤ 0.20.

Inventors:
MATSUMOTO, Yosuke
INADA, Atsushi
CHIBA, Masamichi
URESHINO, Yoshimasa (1 Toyota-cho, Toyota-sh, Aichi 71, 〒4718571, JP)
KATO, Reiko (1 Toyota-cho, Toyota-sh, Aichi 71, 〒4718571, JP)
Application Number:
JP2014/074393
Publication Date:
April 02, 2015
Filing Date:
September 16, 2014
Export Citation:
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Assignee:
KABUSHIKI KAISHA KOBE SEIKO SHO(KOBE STEEL, LTD.) (2-4 Wakinohama-Kaigandori 2-chome, Chuo-ku Kobe-sh, Hyogo 85, 〒6518585, JP)
International Classes:
C22C38/00; C21D1/18; C21D9/00; C22C38/50; F16B35/00
Foreign References:
JP2006291295A2006-10-26
JP2011047010A2011-03-10
JP2006045670A2006-02-16
JPH09263876A1997-10-07
JP2004076086A2004-03-11
JPH06271975A1994-09-27
JPH1017985A1998-01-20
JP2004084010A2004-03-18
JP2007031734A2007-02-08
Other References:
See also references of EP 3050987A4
Attorney, Agent or Firm:
UEKI, Kyuichi et al. (Fujita-Toyobo Building 9th floor, 1-16 Dojima 2-chome, Kita-ku, Osaka-sh, Osaka 03, 〒5300003, JP)
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