Effects of Stress Ratio on Fatigue Crack Growth Rates in X70 Pipeline Steel in Air and Saltwater

    Volume 8, Issue 2 (March 1980)

    ISSN: 0090-3973

    CODEN: JTEOAD

    Page Count: 6


    Vosikovsky, O
    Research scientist, Canada Centre for Mineral and Energy Technology, Physical Metallurgy Research Laboratories, Ottawa, Ontario

    Abstract

    Fatigue crack growth rates in an X70 pipeline steel were measured over a wide range of stress intensities in laboratory air and in 3.5% sodium chloride solution under free corrosion and cathodic (coupled to zinc) potentials. The effects of stress ratio in all these environments and of cyclic frequency in the sodium chloride solution were studied. The results are compared with fatigue crack growth rates measured previously in lower strength X65 steel. The stress ratio strongly influences the fatigue crack growth thresholds and close-to-threshold growth rates. With increasing stress intensity range, the stress ratio effect decreases similarly in both air and aqueous environments. The lower cyclic frequency enhances corrosion fatigue crack growth rates at intermediate stress intensity ranges, as was observed earlier in X65 steel.


    Paper ID: JTE10597J

    DOI: 10.1520/JTE10597J

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    Author
    Title Effects of Stress Ratio on Fatigue Crack Growth Rates in X70 Pipeline Steel in Air and Saltwater
    Symposium , 0000-00-00
    Committee E08