STP727: An Electrochemical Technique to Measure Diffusible Hydrogen in Metals (Barnacle Electrode)

    DeLuccia, JJ
    Division superintendent and research chemist, Aeronautical Materials Division, Aircraft and Crew Systems Technology Directorate, Naval Air Development Center, Warminster, Pa.

    Berman, DA
    Division superintendent and research chemist, Aeronautical Materials Division, Aircraft and Crew Systems Technology Directorate, Naval Air Development Center, Warminster, Pa.

    Pages: 18    Published: Jan 1981


    Abstract

    The electrochemical measurement of mobile hydrogen, utilized in hydrogen-through-iron permeation studies, is adapted to yield an extremely sensitive, yet simple, practical device to assess embrittlement in high-strength steel parts. The electrochemical permeation of hydrogen through metal foils is achieved by causing an electrochemical source and sink for hydrogen to co-exist on either side of a foil. The hydrogen is cathodically introduced at the input side and anodically extracted (oxidized to water) at the exit side. The extraction side of the permeation cell provides the basis for the barnacle electrode hydrogen measurement device. The hydrogen oxidation current is measured and related to the mobile hydrogen concentration by the solution to the diffusion equation using the appropriate boundary conditions. The device can accurately detect and measure diffusible hydrogen contents in the range of 100 parts per billion by weight. Its effectiveness has been demonstrated in (1) indexing embrittlement of high-strength AISI 4340 steel as a function of hydrogen content, (2) the loss of hydrogen in an HY-130 steel weldment, and (3) changes in hydrogen content of cadmium plated steel which were measured, leading to a better understanding of bakeout and delayed failure mechanisms.

    Keywords:

    hydrogen embrittlement, embrittlement indexing, mobile hydrogen, hydrogen permeation, hydrogen measurement, environmental embrittlement, electrochemical technique, barnacle electrode, high strength steels, sustained load testing, electroplating


    Paper ID: STP28037S

    Committee/Subcommittee: G01.11

    DOI: 10.1520/STP28037S


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