Morphology of γ′ Precipitates in a First Stage Low Pressure Turbine Blade of a Ni-Based Superalloy after Service and after Following Aging

    Volume 9, Issue 2 (February 2012)

    ISSN: 1546-962X

    CODEN: JAIOAD

    Published Online: 4 October 2011

    Page Count: 9


    Miura, Nobuhiro
    National Defense Academy,

    Kondo, Yoshihiro
    National Defense Academy,

    (Received 11 October 2010; accepted 5 September 2011)

    Abstract

    To estimate the temperature distribution, stress distribution, and stress direction in a blade in service, the morphology of γ′ precipitates in Ni-based superalloy serviced in the first stage low pressure turbine (1st LPT) blade of a jet engine was investigated before and after aging. Using a field emission scanning electron microscope, microstructures were observed in forty portions of the blade. Most of the γ′ precipitates remained cuboidal in the serviced blade. Many secondary γ′ precipitates were observed in the γ matrix at the root part. In contrast, there were no secondary γ′ precipitates at the leading edge of the tip part. After simple aging, low-completion rafted γ/γ′ structures appeared on the suction side of the 70 mm part, while in other portions, coarsening of the γ′ precipitates was observed. Therefore, the leading edge of the 1st LPT blade tip was exposed to the highest temperatures in service. However, the stresses were extremely low in all portions of the blade.


    Paper ID: JAI103463

    DOI: 10.1520/JAI103463

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    Title Morphology of γ′ Precipitates in a First Stage Low Pressure Turbine Blade of a Ni-Based Superalloy after Service and after Following Aging
    Symposium , 0000-00-00
    Committee E08