STP1419: Local Elasto-Plastic Properties of Bearing Steels determined by Nano-Indentation Measurements

    Vincent, A
    Professor, research scientist and assistant professor, Groupe ďEtudes de Métallurgie Physique et de Physique des Matériaux (U.M.R. C.N.R.S. 5510) / I.N.S.A., Villeurbanne,

    Elghazal, H
    Professor, research scientist and assistant professor, Groupe ďEtudes de Métallurgie Physique et de Physique des Matériaux (U.M.R. C.N.R.S. 5510) / I.N.S.A., Villeurbanne,

    Lormand, G
    Professor, research scientist and assistant professor, Groupe ďEtudes de Métallurgie Physique et de Physique des Matériaux (U.M.R. C.N.R.S. 5510) / I.N.S.A., Villeurbanne,

    Hamel, A
    Professor, research scientist and assistant professor, Groupe ďEtudes de Métallurgie Physique et de Physique des Matériaux (U.M.R. C.N.R.S. 5510) / I.N.S.A., Villeurbanne,

    Girodin, D
    Research engineer, S.N.R. Roulements, Annecy,

    Pages: 16    Published: Jan 2002


    Abstract

    Methods for obtaining local elasto-plastic properties of bearing steels through nano-indentation measurements are described. The usual way to analyze the unloading part of a nano-indentation test in order to obtain the elastic modulus of nonmetallic inclusions or primary carbides in bearing steels is summarized. Then, emphasis is given to a new method mat enables one to derive the profile of micro-plastic properties of a surface hardened bearing steel. Experimentally, it consists of measuring the residual displacement dr of a spherical indenter, following loading-unloading cycles at increasing maximal force Fmax. First, the direct problem, i.e., simulating by the finite element method the nano-indentation response, dr(Fmax), from the knowledge of the strain-hardening law, σ(εp), is studied. It is validated on steel specimens that are carburised homogeneously with different carbon concentrations. Second, the inverse problem, i.e. obtaining the strain-hardening law from the nano-indentation response, is studied on carburised and nitrided layers.

    Keywords:

    Nano-indentation, micro-plasticity, micro-yield stress, surface hardened steel, carburised layer, nitrided layer


    Paper ID: STP10871S

    Committee/Subcommittee: A01.28

    DOI: 10.1520/STP10871S


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