Title:
STEEL FOR AUTOMOBILE UNDERCARRIAGE COMPONENT EXCELLING IN FATIGUE PERFORMANCE AND PROCESS FOR MANUFACTURING AUTOMOBILE UNDERCARRIAGE COMPONENT USING THE STEEL
Document Type and Number:
WIPO Patent Application WO/2008/018624
Kind Code:
A1
Abstract:
A steel for automobile undercarriage component that excels in fatigue performance,
not needing much cost in heat treatment and also excels in molding processability;
and a process for manufacturing an automobile undercarriage component with
the use of the steel. There is provided a steel doped with Nb in combination with
Mo, wherein after bend forming such that the bend radius (R) at plate external
surface becomes 2 to 5 times the thickness of the plate, the difference between
the Vickers hardness at the center of the plate thickness and the maximum value
of Vickers hardness within 0.5 mm from the surface ranges from 50 to 150 points.
As the surface hardness is high with the hardness of the center part lowered,
excellent fatigue performance and molding processability can be attained.
Further, when annealing is carried out under conditions such that temper parameter
(λ) defined by λ=T(20+log(t)) [wherein T: absolute temperature,
t: time (h), and temperature upper limit: 660˚C] ranges from 14,000 to
19,000, a relaxation of internal stress can be achieved to thereby attain a further
enhancement of fatigue performance.
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Inventors:
NAKAMURA HIDEYUKI (JP)
ANAI ISAO (JP)
YAMAMOTO YASUSHI (JP)
FUKUSHI TAKAAKI (JP)
YAMAMOTO IZURU (JP)
KONDO MASAAKI (JP)
SHIMAZU SATORU (JP)
ANAI ISAO (JP)
YAMAMOTO YASUSHI (JP)
FUKUSHI TAKAAKI (JP)
YAMAMOTO IZURU (JP)
KONDO MASAAKI (JP)
SHIMAZU SATORU (JP)
Application Number:
PCT/JP2007/065893
Publication Date:
February 14, 2008
Filing Date:
August 08, 2007
Export Citation:
Assignee:
NIPPON STEEL CORP (JP)
TOYOTA MOTOR CO LTD (JP)
NAKAMURA HIDEYUKI (JP)
ANAI ISAO (JP)
YAMAMOTO YASUSHI (JP)
FUKUSHI TAKAAKI (JP)
YAMAMOTO IZURU (JP)
KONDO MASAAKI (JP)
SHIMAZU SATORU (JP)
TOYOTA MOTOR CO LTD (JP)
NAKAMURA HIDEYUKI (JP)
ANAI ISAO (JP)
YAMAMOTO YASUSHI (JP)
FUKUSHI TAKAAKI (JP)
YAMAMOTO IZURU (JP)
KONDO MASAAKI (JP)
SHIMAZU SATORU (JP)
International Classes:
C22C38/00; B60G9/04; C21D9/00; C22C38/12; C22C38/58
Foreign References:
| JPH05195075A | 1993-08-03 | |||
| JP2004204315A | 2004-07-22 | |||
| JP2005264240A | 2005-09-29 | |||
| JP2005298957A | 2005-10-27 | |||
| JP2001321846A | 2001-11-20 |
Other References:
See also references of EP 2050835A4
Attorney, Agent or Firm:
AOKI, Atsushi et al. (Toranomon 37 Mori Bldg.5-1, Toranomon 3-chom, Minato-ku Tokyo 23, JP)
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