STP536

    Influence of Stress Intensity Level during Fatigue Precracking on Results of Plane-Strain Fracture Toughness Tests

    Published: Jan 1973


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    Abstract

    One of the more troublesome parts of conducting a plane-strain fracture toughness test in accordance with ASTM Test for Plain Strain Fracture Toughness of Metallic Materials (E 399-72) is producing a satisfactory fatigue crack in the specimen prior to fracturing it. The 1968 version of ASTM E 399 indicated that the stress intensity during the last stage of fatigue cracking should not exceed 0.0012 in.½ E (modulus of elasticity) or 0.5 KIc, but that has been gradually eased so that the current limits are 0.002 in.½ E or 0.6 KIc. Data for four aluminum alloys support the fact that it is satisfactory to use stress intensities up to 0.002 in.½ E and suggest that the other limit could be increased to 80 percent of KIc. This may be unique to aluminum alloys, and additional data should be generated for other metals to determine whether or not this is generally true.

    Keywords:

    fracture properties, cracks, aluminum alloys, fracture strength, tests, modulus of elasticity, tests precracking


    Author Information:

    Kaufman, J. G.
    Manager, Aluminum Company of America, New Kensington, Pa.

    Schilling, P. E.
    Engineer, Aluminum Company of America, New Kensington, Pa.


    Paper ID: STP49648S

    Committee/Subcommittee: E08.05

    DOI: 10.1520/STP49648S


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