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Patent Searching and Data


Title:
STEEL WIRE FOR BOLT, BOLT, AND PRODUCTION METHOD THEREFOR
Document Type and Number:
WIPO Patent Application WO/2015/083599
Kind Code:
A1
Abstract:
Provided are: a high-strength bolt that has a tensile strength of 1,000-1,400 MPa and a delayed fracture resistance that is on par with standard steel alloys even when Mo and Cr are omitted or reduced with respect to SCM steel or SCr steel; a steel wire for a bolt that is for producing the aforementioned high-strength bolt; and a useful method for producing the bolt and the steel wire for a bolt. The steel wire for a bolt satisfies a predetermined chemical composition. With regard to the boron content of the surface of the steel wire for a bolt, when the diameter of the steel wire for a bolt is denoted by D0 and the boron content of a D0/4 portion of the steel wire for a bolt is 100%, the average proportion of the boron content of the surface of the steel wire for a bolt is 75% or less and the difference between the maximum value and the minimum value of this proportion is 25% or less. The prior austenite grain size number in an area from the surface of the steel wire for a bolt to a depth of 100 µm is no. 8 or higher.

Inventors:
MATSUMOTO, Yosuke
CHIBA, Masamichi
Application Number:
JP2014/081324
Publication Date:
June 11, 2015
Filing Date:
November 27, 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; C21D8/06; C21D9/00; C22C38/32; C22C38/54; F16B35/00
Domestic Patent References:
WO2006088019A12006-08-24
WO2011108459A12011-09-09
Foreign References:
JP2013227647A2013-11-07
JP2013082963A2013-05-09
JP2012162798A2012-08-30
JP2012041587A2012-03-01
JP2009007644A2009-01-15
JP2001011575A2001-01-16
EP2423344A22012-02-29
JPH1143737A1999-02-16
JPH1053834A1998-02-24
JP2001062639A2001-03-13
Other References:
See also references of EP 3078758A4
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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