STP397: Chemical and Physical Mechanisms of Salt Stress-Corrosion Cracking in the Titanium 8-1-1 Alloy

    Logan, H. L.
    PhysicistPersonal member ASTM, Nat. Bureau of Standards, Washington, D. C.,

    McBee, M. J.
    Chemist, chemist, technologist, and metallurgist, Nat. Bureau of Standards, Washington, D. C.,

    Bechtoldt, C. J.
    Chemist, chemist, technologist, and metallurgist, Nat. Bureau of Standards, Washington, D. C.,

    Sanderson, B. T.
    Chemist, chemist, technologist, and metallurgist, Nat. Bureau of Standards, Washington, D. C.,

    Ugiansky, G. M.
    Chemist, chemist, technologist, and metallurgist, Nat. Bureau of Standards, Washington, D. C.,

    Pages: 15    Published: Jan 1966


    Abstract

    Stress-corrosion tests were performed on hollow cylinders and sheet-metal specimens of Ti-8Al-1Mo-1V in contact with solid sodium chloride or synthetic sea-water salt. Specimens were heated to 750 F and subjected to a 73,500 psi tensile stress. Specimens failed in times as short as 18 hr. The hollow specimens were evacuated and then filled with oxygen or argon. No cracking occurred unless oxygen or water vapor was present. Cracking was also introduced in specimens preoxidized for about 65 hr and coated with sodium chloride in an inert atmosphere under the same condition of temperature and stress. The authors propose that chlorine diffuses down through a stress, and probably an oxygen concentration gradient reacts with the metal to destroy atomic bonds and produce stress corrosion. Specific reactions, however, have not yet been determined. X-ray diffraction studies of corrosion products indicate that the usual oxides of titanium are present along with an unidentified phase that may be formed by reaction between sodium chloride, oxygen, and the alloy.

    Keywords:

    titanium alloys, stress corrosion, stress-corrosion tests, sodium chloride, chlorine, diffusion


    Paper ID: STP46435S

    Committee/Subcommittee: E08.06

    DOI: 10.1520/STP46435S


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