STP425

    Environmental Factors Affecting the Stress Corrosion Cracking Behavior of an Aluminum-Zinc-Magnesium Alloy

    Published: Jan 1967


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    Abstract

    The stress corrosion cracking phenomenon in an aluminumzinc-magnesium alloy is affected by the environmental factors in a different fashion than the way these factors affect other corrosion processes. The presence of traces of moisture is sufficient for stress corrosion cracking to proceed; the absence of moisture prevents cracking. The time required to initiate stress corrosion cracking is affected mostly by the temperature of the environment. Wide variations in sodium chloride concentration have no effect on the time-to-failure. Changes in solution pH and contamination with dissolved copper alter the time required to produce failure, so that stress corrosion cracking is not a continuous function of either variable. Evidence is presented which shows that the manner of stressing a specimen and specimen configuration both affect failure time. These anomalies may be used to understand the lack of reproducibility of stress corrosion testing and the difficulties encountered in correlation studies, either among different tests or the same test carried out by different laboratories.

    Keywords:

    corrosion, stress corrosion, environmental testing, cracking (fracturing), aluminum alloys, zinc alloys, magnesium alloys, sodium chloride, pH, copper ions, temperature, humidity, immersion tests (corrosion)


    Author Information:

    Romans, H. B.
    Scientist and research supervisorPersonal members ASTM, Reynolds Metals Co., Richmond, Va.

    Craig, H. L.
    Scientist and research supervisorPersonal members ASTM, Reynolds Metals Co., Richmond, Va.


    Paper ID: STP46469S

    Committee/Subcommittee: G01.05

    DOI: 10.1520/STP46469S


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