STP516: Simplified Exfoliation Testing of Aluminum Alloys

    Sprowls, DO
    Section head, technician, and senior research engineer, Alcoa Research Laboratories, New Kensington, Pa.

    Walsh, JD
    Section head, technician, and senior research engineer, Alcoa Research Laboratories, New Kensington, Pa.

    Shumaker, MB
    Section head, technician, and senior research engineer, Alcoa Research Laboratories, New Kensington, Pa.

    Pages: 28    Published: Jan 1972


    Abstract

    A program was undertaken to develop accelerated tests to determine susceptibility to exfoliation in aluminum alloys. Experimentation was concentrated on total immersion procedures to develop a simple, easily controlled test. Chloride solutions did not cause exfoliation during immersion; however, formulations of chloride-nitrate solutions were found that produced severe exfoliation of highly susceptible Al-Mg-Mn alloy specimens in only one or two days. Investigation of the most effective chloride-nitrate ratios, concentrations, solution pH, and temperature led to the development of a new, simple, and rapid exfoliation test for Al-Mg-Mn alloys. Additional investigation resulted in the development of similar test media for Al-Cu-Mg, Al-Zn-Mg, and Al-Zn-Mg-Cu alloys, and showed that the optimum test conditions differ for the separate alloy families.

    Test data are presented for alloys 2024, 5086, 5456, 7005, 7075, and 7178 in metallurgical conditions that provide comparisons of high and low resistance to exfoliation. Comparisons with exposures to natural environments also are included.

    Keywords:

    corrosion, exfoliation corrosion, seawater corrosion, corrosion tests, salt spray tests, immersion tests (corrosion), aluminum alloys


    Paper ID: STP35415S

    Committee/Subcommittee: G01.14

    DOI: 10.1520/STP35415S


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