• Login
    View Item 
    •   SMARTech Home
    • Georgia Tech Theses and Dissertations
    • Georgia Tech Theses and Dissertations
    • View Item
    •   SMARTech Home
    • Georgia Tech Theses and Dissertations
    • Georgia Tech Theses and Dissertations
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Study of rotational fretting of quenched and tempered 4340 steel

    Thumbnail
    View/Open
    MATHEW-THESIS-2014.pdf (8.474Mb)
    Date
    2013-07-08
    Author
    Mathew, Paul
    Metadata
    Show full item record
    Abstract
    Fretting phenomenon occurs when two bodies in contact undergo small repetitive relative motion such that the localized surface and subsurface material properties are altered leading to damage or failures. Fretting conditions are obtained by controlling externally applied parameters such as load, frequency of displacement, displacement amplitude. Material properties which influence fretting behavior include hardness, ductility, hardening behavior. External parameters like surface roughness, temperature also play a role in deciding the extent of damage. Based on fretting conditions and specimen geometry, various fretting modes can be classified. Rotational fretting is one such damage mode, observed in industrial applications such as cable ropes under tension used for support in construction industry and variable stator vanes (VSVs) in compressors of turbines. In spite of industrial and engineering relevance, rotational fretting has received little attention. In the present work, rotational fretting of self-mated AISI 4340 material pair was studied, with the objective of characterizing subsurface damage induced by fretting. AISI 4340 (EN 24) is a low alloy martensitic steel with an excellent combination of strength, ductility and toughness. It is widely used in high strength cyclic loading applications like gears, bearings, automobile pistons and aircraft landing gears as well as in low corrosion, high strength offshore applications. It can be readily machined and surface hardened which makes it useful for wear related applications. A novel rotational fretting test set up, capable of operating under various test loads, frequencies, displacement amplitudes and temperatures was used to perform experiments. Specimens were subjected to a combination of normal load and rotational displacement and caused to mutually contact on non-conformal curved surfaces which simulate a bearing or bushing geometry. Fretting results were primarily determined by the frictional torque versus angular displacement plots. The running condition response was linked to the fretting material response regime. Surface and subsurface characterization studies of fretted regions were conducted using Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). TEM studies revealed varying levels of fretting induced plastic deformation within the fretted contact zone. Good correlation with available literature relating to formation of dislocation cells and presence of high dislocation density in the fretting damaged regions was established. Although quantifying the dislocation density as a damage indicator is a challenge, it is proposed that a microstructural feature based approach has the potential to be developed into a useful tool for life assessment and life prediction studies.
    URI
    http://hdl.handle.net/1853/51771
    Collections
    • Georgia Tech Theses and Dissertations [23877]
    • School of Mechanical Engineering Theses and Dissertations [4086]

    Browse

    All of SMARTechCommunities & CollectionsDatesAuthorsTitlesSubjectsTypesThis CollectionDatesAuthorsTitlesSubjectsTypes

    My SMARTech

    Login

    Statistics

    View Usage StatisticsView Google Analytics Statistics
    facebook instagram twitter youtube
    • My Account
    • Contact us
    • Directory
    • Campus Map
    • Support/Give
    • Library Accessibility
      • About SMARTech
      • SMARTech Terms of Use
    Georgia Tech Library266 4th Street NW, Atlanta, GA 30332
    404.894.4500
    • Emergency Information
    • Legal and Privacy Information
    • Human Trafficking Notice
    • Accessibility
    • Accountability
    • Accreditation
    • Employment
    © 2020 Georgia Institute of Technology