STP767: Accelerated Atmospheric-Corrosion Testing

    Khobaib, M
    Coauthor Chang, Systems Research Laboratories, Inc.Army Materials and Mechanics Research Center, DaytonWatertown, OhioMass.

    Chang, FC
    Coauthor Chang, Systems Research Laboratories, Inc.Army Materials and Mechanics Research Center, DaytonWatertown, OhioMass.

    Keppler, EE
    Coauthor Chang, Systems Research Laboratories, Inc.Army Materials and Mechanics Research Center, DaytonWatertown, OhioMass.

    Lynch, CT
    Air Force Wright Aeronatical Laboratories, Wright-Patterson Air Force Base, Ohio

    Pages: 21    Published: Jan 1982


    Abstract

    No accurate methods are known for accelerated testing of corrosion which yield reliable results for predicting the service life of aircraft components and materials which degrade or fail due to environmental attack. In an effort to provide the basis for development of realistic accelerated corrosion tests, research is being conducted in controlled atmospheres on the localized environmental enhancement of crack-growth rates of aerospace alloys. Corrosion-fatigue and rising-load experiments have been conducted using accelerating pollutants such as sulfur dioxide (SO2) and ambient air to 100 percent relative humidity air in a specially designed atmospheric chamber. Initial results indicate that realistic environmental enhancement of crackgrowth rates can be employed to develop accelerated tests which can be related to actual in-service degradation. For materials with high stress-corrosion susceptibility, the threshold for crack growth (KIscc) was estimated to be 45 to 46 MPa √m for 4340 steel at a 1440-MPa yield strength level, as compared to 49 to 52 MPa √m as determined by means of rising-load test and 44 to 46 MPa √m by fracture analysis in 1000-ppm SO2 at 80 percent relative humidity. Thus, a rapid and reproducible method for KIscc determination appears feasible.

    Keywords:

    accelerated corrosion testing, realistic environments, crack growth, localized environmental enhancement, rising-load testing, low-cycle corrosion fatigue


    Paper ID: STP33204S

    Committee/Subcommittee: G01.04

    DOI: 10.1520/STP33204S


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