Study on crack opening displacement and hydrogen enhanced cruck propagation of low alloy steel

Yoshiyuki Kondo, Masanobu Kubota, Koshiro Mizobe

    Research output: Contribution to journalArticlepeer-review

    2 Citations (Scopus)

    Abstract

    Crack propagation rate of SCM440H low alloy steel under long term varying load is enhanced by absorbed hydrogen. Substantial acceleration of crack propagation rate up to 100 times was observed. Macroscopic approach to examine the role of hydrogen on the acceleration was investigated by changing loading condition and charging condition. ( 1 ) The predominant fracture mode of hydrogen charged material showing acceleration was quasi cleavage. The application of stress prior to hydrogen charge prevented the quasi cleavage cracking in the following hydrogen-charged condition. This suggests that hydrogen restrained blunting of crack tip, which resulted in relatively higher stress state in hydrogen charged material. The higher stress state caused quasi cleavage and acceleration of crack propagation. ( 2 ) The crack opening displacement (COD) was measured on hydrogen charged material and uncharged material. COD was smaller in hydrogen charged material. The stress for the onset of non-linear deformation in stress-COD relation was higher in hydrogen charged material. These examinations suggested that the mechanistic role of hydrogen is to prevent the blunting of crack tip and bring about higher stress field near the crack tip.

    Original languageEnglish
    Pages (from-to)594-601
    Number of pages8
    JournalNihon Kikai Gakkai Ronbunshu, A Hen/Transactions of the Japan Society of Mechanical Engineers, Part A
    Volume76
    Issue number765
    DOIs
    Publication statusPublished - May 2010

    All Science Journal Classification (ASJC) codes

    • Materials Science(all)
    • Mechanics of Materials
    • Mechanical Engineering

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