STP866

    An Improved Intergranular Corrosion Test for HASTELLOY® Alloy C-276

    Published: Jan 1985


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    Abstract

    Presently, the most widely used susceptibility test for intergranular corrosion of HASTELLOY® Alloy C-276 is the ferric sulfate-sulfuric acid test. The corrosion rate obtained by this test has uniform and intergranular corrosion components. The uniform corrosion rate, which is a function of minor variations in alloy chemistry, may easily mask the intergranular corrosion component of the overall corrosion rate. A new solution chemistry identified through laboratory tests resolves the problem and displays a step function response in corrosion rate when there are high levels of grain boundary precipitation. Over 700 production specimens have been comparatively tested in both solutions, spanning a time period of two years. The new test consistently detects undesirable microstructural conditions in HASTELLOY Alloy C-276 that, in many cases, are not detected by the ferric sulfate-sulfuric acid test.

    Keywords:

    corrosion, intergranular corrosion, pitting, NiCrMo alloy, sensitization, ASTM G 28


    Author Information:

    Manning, PE
    Corrosion group leader, Cabot Corporation, Kokomo, IN


    Paper ID: STP33796S

    Committee/Subcommittee: G01.05

    DOI: 10.1520/STP33796S


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