Fatigue crack nuclei in austempered ductile cast iron

T. J. Marrow, H. Çetinel, M. Al-Zalmah, S. Macdonald, P. J. Withers, J. Walton

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Short fatigue crack nuclei in austempered ductile cast iron have been studied using optical microscopy, scanning electron microscopy, atomic force microscopy and X-ray microtomography and by electron backscatter diffraction analysis. Fatigue cracks nucleate at graphite nodules and shrinkage microporosity. The crack nuclei are arrested and retarded by barriers in the microstructure, by either blocking of slip at boundaries or owing to the requirement for tilt and twist of the stage I crystallographic crack at grain boundaries. These observations indicate that both the size of the defects, such as graphite nodules and microporosity, and the size of the prior austenite grains control the largest crack nucleus that can develop, and hence determine the component fatigue limit.
    Original languageEnglish
    Pages (from-to)635-648
    Number of pages13
    JournalFatigue and Fracture of Engineering Materials and Structures
    Volume25
    Issue number7
    DOIs
    Publication statusPublished - Jul 2002

    Keywords

    • Austempered ductile cast iron
    • Fatigue limit
    • Short cracks

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