STP771

    Effect of Platelike Carbides Below the Rolling Surface in a Ball-Washer Thrust Rolling Contact Fatigue Tester

    Published: Jan 1982


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    Abstract

    It has been observed that platelike carbides form immediately underneath the rolling track of a specimen subjected to rolling contact fatigue tests on the ball-washer thrust type of tester. These carbides are less likely to form when the carbon concentration of the martensite matrix is low and more likely to present themselves when the carbon content is high.

    Carbon is diffused in the matrix by repeated stresses in the specimen during rolling contacts. This carbon is caught by dislocations between oxide inclusions in fields right beneath the rolling track, where the density of such dislocations is high, and it precipitates as carbide.

    We have assumed that flakings of the specimen from rolling contact fatigue are attributable to the development and propagation of cracks which originate at the site of the platelike carbides under the rolling track. In order to improve the rolling contact fatigue strength of bearing steel, it is necessary to lower the carbon concentration of the matrix while maintaining the hardness required for the rolling element, and also to reduce and finely disperse oxide inclusions.

    Keywords:

    ball-washer thrust-type rolling contact fatigue tester, microstructural alteration, platelike carbide, rolling contact fatigue mechanism, bearing steels


    Author Information:

    Tsubota, K
    Manager, Research Section II, Technological Research Laboratory, and managing director and general manager, Technical Administration Headquarters, Sanyo Special Steel Co., Ltd., Himeji,

    Koyanagi, A
    Manager, Research Section II, Technological Research Laboratory, and managing director and general manager, Technical Administration Headquarters, Sanyo Special Steel Co., Ltd., Himeji,


    Paper ID: STP36150S

    Committee/Subcommittee: A01.28

    DOI: 10.1520/STP36150S


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