STP610: Removal of Iron-Sulfide Deposits from Fracture Surfaces

    Interrante, CG
    Metallurgists, National Bureau of Standards, Washington, D. C.

    Hicho, GE
    Metallurgists, National Bureau of Standards, Washington, D. C.

    Pages: 17    Published: Jan 1976


    Abstract

    Steels are most commonly used at moderate strength levels at which they have high ductility and resistance to subcritical crack growth due to hydrogen. Thus, in testing the susceptibility to hydrogen damage of these steels, severe charging conditions are commonly used, and hydrogen sulfide is often used in low-pH solutions to obtain the desired high fugacity for the test. The fracture faces of specimens tested in this type of solution become covered with iron and other sulfides that are difficult to remove without affecting the underlying metal as well. The removal of these sulfide deposits from the fracture surfaces is a prerequisite to fractographic analysis of the failure mode, and it was attempted by various methods. Hydrogen reduction of the sulfides at elevated temperatures followed by ultrasonic cleaning in alcohol was found to be much more successful than the other methods studied. This is true principally because the hydrogen-reduction treatment did not attack the fracture surface. Procedures for four different cleaning treatments are described, and they are rated in terms of their relative capability for cleaning sulfide-contaminated fracture surfaces without affecting the underlying metal. Evaluations of these methods for double-cantilever-beam and Charpy V-notch specimens of a 2¼Cr-1Mo steel with fracture surfaces that were created at various stress-intensity levels provides information needed for studying the cracking mechanism under severe sulfide exposure conditions.

    Keywords:

    stress corrosion, crack propagation, ductility, hydrogen, failure, fracture tests, steels, fractography


    Paper ID: STP28689S

    Committee/Subcommittee: G01.06

    DOI: 10.1520/STP28689S


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