STP302: Influence of Sheet Thickness on Sharp-Edge-Notch Properties of a β Titanium Alloy at Room and Low Temperatures

    Repko, A. J.
    Research Engineer, National Aeronautics and Space Administration Lewis Research Center, Cleveland, Ohio

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

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

    Pages: 18    Published: Jan 1962


    Abstract

    The influence of sheet thickness on the sharp-edge-notch properties of B120 VCA titanium alloy was investigated. Tests were made at both room and low temperatures. Thicknesses between 0.010 and 0.130 in. were obtained by: (1) machining material from one sheet to the desired thickness, (2) rolling material from this same sheet to the desired thickness, and (3) using material from individual heats of various thicknesses. Tests at low temperature were confined to the last condition. Room-temperature data for aged (900 F, 72 hr) sheet were analyzed to yield the absolute effect of thickness on fracture toughness, per cent shear, and slow crack extension. At room temperature, solution treated sheet in all thicknesses was extremely tough. Inherently large differences in the sharp-notch properties between the various heats of aged material obscured the thickness effect when each thickness represented a different heat. The absolute thickness effect for aged material was established by machining the desired thicknesses from a single heat of the alloy. In general this effect corresponded to that expected on the basis of Irwin's fracture mechanics with the exception that no abrupt fracture mode transition was observed and that the slow crack extension was independent of thickness. Regarding the effect of testing temperature, it was shown that the solution treated condition of B120 VCA is very tough down to −110 F but quite brittle at −320 F.


    Paper ID: STP49629S

    Committee/Subcommittee: A01.19

    DOI: 10.1520/STP49629S


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