SYMPOSIA PAPER Published: 01 January 1997

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


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 εfpmσfl) and the crack-tip stress/strain fields governed by alloy flow properties. Uncertainties in εfpmσfl), 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.

Author Information

Haynes, MJ
University of Virginia, Charlottesville, VA
Somerday, BP
University of Virginia, Charlottesville, VA
Lach, CL
NASA Langley Research Center, Hampton, VA
Gangloff, RP
University of Virginia, Charlottesville, VA
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Developed by Committee: E08
Pages: 165–190
DOI: 10.1520/STP16323S
ISBN-EB: 978-0-8031-5356-1
ISBN-13: 978-0-8031-2413-4