STP1256

    The Application of a Logic Framework for Fatigue Crack Growth Analyses to Microstructural Effects

    Published: Jan 1995


      Format Pages Price  
    PDF (500K) 21 $25   ADD TO CART
    Complete Source PDF (17M) 21 $109   ADD TO CART


    Abstract

    △K has been widely used to correlate da/dN data. The relation between da/dN and △K is usually found empirically. However, fatigue crack growth relations can also be derived theoretically. Three fatigue crack growth theories are derived for the state of small scale yielding and plane strain. These three theories constitute a logic framework useful for fatigue crack growth analyses. The application of the logic framework to the analyses of microstructural effects on fatigue crack growth is illustrated.

    The fatigue crack growth curve of 7075-T651 aluminum alloy has five distinct regions. A fatigue crack grows by crack-tip shear decohesion forming striations and by brittle fractures of particles followed by localized shear decohesion at these microcracks forming dimples. The logic framework helps to relate the fatigue crack growth behaviors in these five regions to the fractures of inclusions and to the resistance of grain boundaries and dispersoids to shear decohesion.

    Keywords:

    Fatigue crack growth, microstructure, 7075-T651 aluminum alloy, inclusions, dispersoids, crack-tip shear decohesion, striation, dimple


    Author Information:

    Xu, JG
    Lecturer, Zhejiang University, Hangzhou, Zhejiang

    Liu, HW
    Professor Emeritus, Mechanical Engineering, Syracuse University, Syracuse, NY


    Paper ID: STP16411S

    Committee/Subcommittee: E08.06

    DOI: 10.1520/STP16411S


    CrossRef ASTM International is a member of CrossRef.