STP1297: Micromechanical Modeling of Temperature-Dependent Initiation Fracture Toughness in Advanced Aluminum Alloys

    Haynes, MJ
    Graduate research assistant, University of Virginia, Charlottesville, VA

    Somerday, BP
    Graduate research assistant, University of Virginia, Charlottesville, VA

    Lach, CL
    Research engineer, NASA Langley Research Center, Hampton, VA

    Gangloff, RP
    Professor, University of Virginia, Charlottesville, VA

    Pages: 26    Published: Jan 1997


    The temperature dependence of the plane-strain initiation fracture toughness (KJICi) is modeled micromechanically for a variety of advanced aluminum alloys that fail by microvoid processes. Materials include precipitation-hardened ingot metallurgy, spray formed, submicron-grain-size powder metallurgy, and metal-matrix composite alloys. A critical-plasticstrain-controlled model, employing tensile yield strength, elastic modulus, work hardening, and reduction of area measurements, successfully predicts KJICi versus temperature for eight alloys, providing a strong confirmation of this approach. Modeling shows that KJICi is controlled by the interplay between the temperature dependencies of the intrinsic failure locus fpmσfl) and the crack-tip stress/strain fields governed by alloy flow properties. Uncertainties in fpmσfl), as well as the critical distance (volume) for crack-tip damage evolution, hinder absolute predictions of KJICi. Critical distance (calculated from the model) correlates with the nearest-neighbor spacing of void-nucleating particles and with the extent of primary void growth determined from quantitative fractography. These correlations suggest a means to predict absolute plane-strain fracture toughness.


    fracture toughness, ductile fracture, micromechanical modeling, aluminum alloys, elevated temperature

    Paper ID: STP16323S

    Committee/Subcommittee: E08.09

    DOI: 10.1520/STP16323S

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