Volume 6, Issue 2 (February 2009)

    Statistical Analysis of Fatigue Related Microstructural Parameters for Airframe Aluminum Alloys

    (Received 12 November 2007; accepted 10 November 2008)

    Published Online: 2009

    CODEN: JAIOAD

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    Abstract

    This paper presents the results of statistical analysis of the fatigue related microstructural parameters, mainly on constituent particles and pores, in 7050-T7452 aluminum forging materials. The statistical distributions of the particle and pore area data, which were obtained from the metallographic measurements on polished surfaces, were fitted well with three-parameter lognormal functions. Comparative studies were carried out for the particle and pore size distributions between the core and periphery materials, and between the hand and die forging materials. An extreme value theory-based model was investigated to correlate the overall material particle distribution with the fatigue crack-nucleating particle distribution. The results indicated that the particle size is not the only parameter affecting the fatigue process; other parameters, such as grain size and grain orientation, are also important parameters for microstructure-based fatigue modeling. Therefore, orientation image microscopy (OIM) analyses were carried out on pristine 7050 samples, on different planes, to determine the grain orientation distributions. Finally, a preliminary OIM analysis was performed on a fractured sample to measure the misorientation angles between the grains near the crack nucleation and short crack regions. It is expected that the test observations and quantitative microstructural data could help to understand the effects of microstructure on the fatigue process and develop a microstructure-based fatigue modeling.


    Author Information:

    Liao, Min
    Structures and Materials Performance Laboratory, Institute for Aerospace Research (IAR), National Research Council Canada (NRC), Ottawa

    Chisholm, Kyle
    Structures and Materials Performance Laboratory, Institute for Aerospace Research (IAR), National Research Council Canada (NRC), Ottawa

    Mahendran, Mario
    Structures and Materials Performance Laboratory, Institute for Aerospace Research (IAR), National Research Council Canada (NRC), Ottawa


    Stock #: JAI101558

    ISSN: 1546-962X

    DOI: 10.1520/JAI101558

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    Author
    Title Statistical Analysis of Fatigue Related Microstructural Parameters for Airframe Aluminum Alloys
    Symposium Seventh International ASTM/ESIS Symposium on Fatigue and Fracture Mechanics (36th ASTM National Symposium on Fatigue and Fracture Mechanics), 2007-11-16
    Committee E08