Hydrogen enhanced crack propagation of SCM440H low-alloy steel under long-term varying load

Yoshiyuki Kondo, Masanobu Kubota, Katsuya Shimada

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    17 Citations (Scopus)


    Crack propagation behavior of SCM440H low-alloy steel enhanced by absorbed hydrogen is investigated. Six materials tempered at different temperatures are used. Effects of stress ratio, loading frequency, hold time and material hardness on the crack propagation rate are examined under long-term varying load. Tests have been performed under continuous hydrogen charging, in which the crack tip has been isolated from the electrolyte and kept dry. An acceleration of crack propagation rate about six times compared to the uncharged material is found in all materials. In addition to this, however, an unexpected acceleration of crack propagation up to 1000 times is experienced under certain conditions. In materials with Vickers hardness higher than 280 tested at low frequency, the above marked acceleration is experienced. The crack surface morphology is quasi-cleavage. This critical hardness (HV= 280) is a little lower than the usually accepted critical hardness for delayed failure (HV= 350). In material with Vickers hardness lower than 268, however, such a marked acceleration is not experienced.

    Original languageEnglish
    Pages (from-to)1963-1974
    Number of pages12
    JournalEngineering Fracture Mechanics
    Issue number11
    Publication statusPublished - Jul 2010

    All Science Journal Classification (ASJC) codes

    • Mechanics of Materials
    • Mechanical Engineering
    • General Materials Science


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