STP397

    Investigation of Long-Term Exposure Effects Under Stress of Two Titanium Structural Alloys

    Published: Jan 1966


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    Abstract

    Notched and unnotched sheet specimens of two titanium alloys, Ti-6Al-4V and Ti-8Al-1Mo-1V, were exposed at 650 F and stressed by a cantilever arrangement to 25 to 30 per cent of their yield stress. Specimens were tested for periods up to 20,000 hr as received, coated with salt, coated with a silver brazing alloy, and coated with a silver brazing alloy and salt. A fifth set was prepared like the last but was exposed cyclically to furnace atmosphere for two-week periods and then in a humidity cabinet at 100 F for two weeks. Specimens were studied by optical microscopy, electron microscopy, and X-ray diffraction. Electron microscopy indicates that cracking is primarily intergranular, but transgranular cracks are possible. X-ray diffraction studies show that titanium chloride and sodium titanate are absent from the corrosion products. Silver braze coatings cause rapid surface deterioration. There is a complete loss of adhesion between braze and parent material after a few thousand hours exposure.

    Keywords:

    titanium alloys, stress corrosion, stress-corrosion tests, brazing alloys, sodium chloride


    Author Information:

    Martin, George
    Program managerPersonal member ASTM, North American Aviation, Inc., Los Angeles, Calif.


    Paper ID: STP46429S

    Committee/Subcommittee: E08.06

    DOI: 10.1520/STP46429S


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