STP287: Sharp-Edge-Notch Tensile Characteristics of Several High-Strength Titanium Sheet Alloys at Room and Cryogenic Temperatures

    Espey, G. B.
    Research Engineer, National Aeronautics and Space Administration, Cleveland, Ohio

    Jones, M. H.
    Research Engineer, National Aeronautics and Space Administration, Cleveland, Ohio

    Brown, W. F.
    Chief, National Aeronautics and Space Administration, Cleveland, Ohio

    Pages: 34    Published: Jan 1961


    Abstract

    The 1-in. wide sharp edge notch tensile test was used to establish the notch sensitivity of several titanium sheet alloys including those of interest in the DOD Titanium Alloy Sheet Rolling Program. The influence of aging temperature was investigated in room-temperature tests and selected alloy conditions were also evaluated at −320 and −423 F. Room-temperature notch sensitivity develops with the aging reaction being most pronounced for the fully aged conditions and decreasing with overaging. A considerable reduction in notch sensitivity in some alloys can be obtained by overaging with relatively small loss in yield strength. At tensile strength to density ratios below about 1,000,000, the best ferritic steels known to the authors have notch sensitivities essentially equal to the poorest of the titanium alloys investigated. At higher strength to density values, the superiority of the titanium alloys rapidly increases. However, it should be noted that the strongest conditions of the titanium alloys possess fracture toughness, KC2, values sufficiently low that careful attention must be given to elimination of flaws in highly stressed components. At cryogenic temperatures, the titanium alloys exhibited higher notch sensitivity than alloys now normally employed for light weight cryogenic tankage. However, the −320 F and −423 F yield strength to density ratios of the commonly used materials are from 40 to 50 per cent lower than obtainable from titanium alloys. The elongation for several of the investigated titanium alloys exhibited a sharp drop between −320 F and −423 F. However, an equally sharp transition in the notch properties did not occur in this temperature range.


    Paper ID: STP46978S

    Committee/Subcommittee: E28.10

    DOI: 10.1520/STP46978S


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