Title:
DELAYED-FRACTURE-RESISTANT BORON-CONTAINING STEEL FOR HIGH-STRENGTH BOLTS, AND HIGH-STRENGTH BOLTS
Document Type and Number:
WIPO Patent Application WO/2012/098938
Kind Code:
A1
Abstract:
The present invention provides, without adding an expensive alloying element such as Cr or Mo in a large amount, a boron-containing steel for high-strength bolts which combines excellent delayed fracture resistance and high strength of 1100MPa or more. This boron-containing steel contains 0.20 to less than 0.40% of C, 0.20 to 1.50% of Si, 0.30 to 2.0% of Mn, up to 0.03% (exclusive of 0%) of P, up to 0.03% (exclusive of 0%)of S, 0.05 to 1.0% of Ni, 0.01 to 1.50% of Cr, up to 1.0% (inclusive of 0%) of Cu, 0.01 to 0.10% of Al, 0.01 to 0.1% of Ti, 0.0003 to 0.0050% of B and 0.002 to 0.010% of N, and contains one ore more elements selected from the group consisting of Cu, Ni and Cr in a total amount of 0.10 to 3.0% with the balance consisting of iron and unavoidable impurities and the [Si]/[C] ratio being 1.0 or more. Further, the boron-containing steel has a ferrite/pearlite dual-phase structure.
Inventors:
MATSUMOTO YOUSUKE
INADA ATSUSHI
CHIBA MASAMICHI
INADA ATSUSHI
CHIBA MASAMICHI
Application Number:
PCT/JP2012/050157
Publication Date:
July 26, 2012
Filing Date:
January 06, 2012
Export Citation:
Assignee:
KOBE STEEL LTD (JP)
MATSUMOTO YOUSUKE
INADA ATSUSHI
CHIBA MASAMICHI
MATSUMOTO YOUSUKE
INADA ATSUSHI
CHIBA MASAMICHI
International Classes:
C22C38/00; C21D9/00; C22C38/58; F16B35/00
Foreign References:
| JPS5591935A | 1980-07-11 | |||
| JPH11124623A | 1999-05-11 | |||
| JPS596358A | 1984-01-13 | |||
| JP2004307932A | 2004-11-04 | |||
| JP2000212696A | 2000-08-02 | |||
| JPH0770695A | 1995-03-14 |
Attorney, Agent or Firm:
UEKI, Kyuichi et al. (JP)
Hisakazu Ueki (JP)
Hisakazu Ueki (JP)
Download PDF:
Claims: