Title:
METHOD FOR IMPROVING FATIGUE STRENGTH OF CAST IRON MATERIAL
Document Type and Number:
WIPO Patent Application WO/2012/073629
Kind Code:
A1
Abstract:
The purpose of the present invention is to provide a method for improving fatigue strength that is capable of improving the fatigue strength of cast iron, specifically spherical graphite cast iron, to the same level as that of carbon steel subjected to carburizing and quenching. To this end, this method contains a step for performing first, second and third shot peenings using shot of a prescribed diameter for each on spherical graphite cast iron on which a tempering heat treatment has been performed at 150-300°C and tensile strength made to be 800MPa or more, the spherical graphite cast iron containing the following elements in the following mass percentages: C=2.0-4.0%, Si=1.5-4.5%, Mn=2.0% or less, P=0.08% or less, S=0.03% or less, Mg=0.02-0.1%, and Cu=1.8-4.0%.
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Inventors:
NOZAKI YOSHIHIKO (JP)
TAGUCHI MAKOTO (JP)
HIRAKAWA KAZUHIRO (JP)
TAGUCHI MAKOTO (JP)
HIRAKAWA KAZUHIRO (JP)
Application Number:
PCT/JP2011/075033
Publication Date:
June 07, 2012
Filing Date:
October 31, 2011
Export Citation:
Assignee:
UD TRUCKS CORP (JP)
NOZAKI YOSHIHIKO (JP)
TAGUCHI MAKOTO (JP)
HIRAKAWA KAZUHIRO (JP)
NOZAKI YOSHIHIKO (JP)
TAGUCHI MAKOTO (JP)
HIRAKAWA KAZUHIRO (JP)
International Classes:
B22D29/00; B22D27/20; B24C1/10; C21D5/00; C21D7/06; C21D9/00; C21D9/30; C21D9/32; C22C37/04
Foreign References:
| JPH0987795A | 1997-03-31 | |||
| JP2007307678A | 2007-11-29 | |||
| JPH11207522A | 1999-08-03 | |||
| JPH09279229A | 1997-10-28 | |||
| JPH09217142A | 1997-08-19 | |||
| JP2009191342A | 2009-08-27 | |||
| JP2000239780A | 2000-09-05 | |||
| JPH1162945A | 1999-03-05 |
Attorney, Agent or Firm:
Patent Corporate Body TAKAHASHI Office (JP)
Patent business corporation Takahashi patent firm (JP)
Patent business corporation Takahashi patent firm (JP)
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Claims: