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Document Type and Number:
WIPO Patent Application WO/2017/119224
Kind Code:
The present invention relates to a large crankshaft having a pin fillet portion, the large crankshaft being characterized in that: an average initial compressive stress of a surface layer region having a depth of 500 μm from the surface of the pin fillet portion is 500 MPa or greater; an average Vickers hardness of the surface of the pin fillet portion is 600 or greater; an arithmetic average roughness Ra of the surface of the pin fillet portion is 1.0 μm or less; and a prior austenite average grain size of a metallographic structure is 100 μm or less. The large crankshaft preferably has a composition that includes 0.2 to 0.4% by mass of C, 0 to 1.0% by mass of Si, 0.2 to 2.0% by mass of Mn, 0.005 to 0.1% by mass of Al, and 0.001 to 0.02% by mass of N with the remainder being Fe and incidental impurities.

TAKAOKA, Hiroyuki
YAMADA, Mariko
Application Number:
Publication Date:
July 13, 2017
Filing Date:
December 02, 2016
Export Citation:
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KABUSHIKI KAISHA KOBE SEIKO SHO (KOBE STEEL, LTD.) (2-4 Wakinohama-Kaigandori 2-chome, Chuo-ku Kobe-sh, Hyogo 85, 〒6518585, JP)
International Classes:
C21D9/30; C22C38/00; C22C38/06; C22C38/58; F16C3/08; B21J5/00; B21K1/08; C21D1/06; C21D8/06
Foreign References:
Other References:
HIDEAKI NAGASAKA ET AL.: "Fatigue Strength Improvements of Solid Type Crankshafts through Fillet Cold Rolling", KOBE STEEL ENGINEERING REPORTS, vol. 48, no. 1, April 1998 (1998-04-01), pages 68 - 71, XP055513142
BARAGETTI, SERGIO ET AL.: "A Numerical and Experimental Investigation on the Fatigue Behavior of a Steel Nitrided Crankshaft for High Power IC Engines", JOURNAL OF ENGINEERING MATERIALS AND TECHNOLOGY, vol. 132, no. 3, 24 July 2010 (2010-07-24), pages 1 - 11, XP009511777, DOI: 10.1115/1.4001834
Attorney, Agent or Firm:
KOTANI, Etsuji et al. (Osaka Nakanoshima Building 2nd Floor, 2-2 Nakanoshima 2-chome, Kita-ku, Osaka-sh, Osaka 05, 〒5300005, JP)
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