STP1085: Corrosion Fatigue Crack Arrest in Aluminum Alloys

    Wanhill, RJH
    National Aerospace Laboratory, Amsterdam,

    Schra, L
    National Aerospace Laboratory, Amsterdam,

    Pages: 22    Published: Jan 1990


    Abstract

    The economic life of airframes is largely determined by widespread initiation and growth of fatigue cracks at low stress intensities. Any factor reducing the low stress-intensity fatigue damage rate could, if controllable, increase the structural durability. One such factor is corrosion fatigue crack retardation and arrest. This was investigated for two high-strength aluminum alloys. Results indicate that two mutually competitive processes, hydrogen embrittlement and crack-tip blocking by corrosion products, have opposing effects on low stress-intensity fatigue. Crack blocking is dominant at the lowest stress intensities. Prospects for enhancing corrosion fatigue crack arrest are reasonable. It is suggested that multifunctional inhibitors could be added to the environment and metal surface treatments to promote corrosion product buildup and prevent hydrogen entry at the crack tip.

    Keywords:

    aluminum alloys, corrosion fatigue, fatigue crack growth, fatigue thresholds, fractography, fracture mechanisms, hydrogen embrittlement


    Paper ID: STP23539S

    Committee/Subcommittee: E08.04

    DOI: 10.1520/STP23539S


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