Microstructure and Fatigue Strength of the Bearing Steel 52100 after Shortened Bainitic Treatment

    Volume 7, Issue 2 (February 2010)

    ISSN: 1546-962X

    CODEN: JAIOAD

    Published Online: 21 December 2009

    Page Count: 10


    Dong, J.
    Scientific Assistant, Foundation Institute of Materials Science, Bremen,

    Vetters, H.
    Professor, Foundation Institute of Materials Science, Bremen,

    Hoffmann, F.
    Professor, Foundation Institute of Materials Science, Bremen,

    Zoch, Hans W.
    Professor, Foundation Institute of Materials Science, Bremen,

    (Received 14 May 2009; accepted 13 November 2009)

    Abstract

    Quenching to obtain martensite is the mostly applied process for standard rolling element bearings. Isothermal treatment in the lower bainitic range is used as an alternative method to generate favorable compressive residual stress on the surface of components, e.g., in spherical roller bearings. The duration of the bainitic treatment, however, is much longer than that of a martensitic treatment because more or less a complete transformation of austenite to bainite is usually requested. This causes higher energy consumption and a longer production period. Therefore it is desirable to perform bainitic treatment with a shortened process duration. In the present work possible processes for shortening the bainitic treatment of the bearing steel 52100 were primarily investigated by dilatometric experiments. Some selected processes were carried out in an industrial salt bath. The microstructures of bainite were observed by optical microscope, transmission electron microscope, and field emission scanning electron microscope. These were compared to martensitic microstructures. The cyclic fatigue strength of the steel after shortened bainitic treatments was examined using a rotating-bar fatigue test. The results show that the fatigue resistance while maintaining the requested minimum hardness of 58 HRC was even enhanced significantly through the shortened treatments particularly by means of a two-step bainitic treatment. The process duration was only about 25 % of the conventional time. The influence of the bainitic microstructure on the fatigue strength of the steel is discussed.


    Paper ID: JAI102511

    DOI: 10.1520/JAI102511

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    Author
    Title Microstructure and Fatigue Strength of the Bearing Steel 52100 after Shortened Bainitic Treatment
    Symposium Eighth International Symposium on Bearing Steel Technologies: Developments in Rolling Bearing Steels and Testing, 2009-05-22
    Committee A01