STP520: Combined Creep-Fatigue Behavior of Inconel Alloy X-750

    Venkiteswaran, PK
    Research assistant and associate professors, University of Waterloo, Waterloo, Ont.

    Ferguson, DC
    Research assistant and associate professors, University of Waterloo, Waterloo, Ont.

    Taplin, DMR
    Research assistant and associate professors, University of Waterloo, Waterloo, Ont.

    Pages: 11    Published: Jan 1973


    Abstract

    A study has been made of the effect of superimposing a small lateral vibratory stress on the axial creep behavior of Inconel Alloy X-750 at 700 C. Tests were conducted in a specially designed creep-fatigue testing machine using specimens simulating gas turbine blades. From preliminary data in combined creep-fatigue, it was found that the creep rate was lower and rupture life higher by almost an order of magnitude compared to the creep values. Fracture mode in combined creep-fatigue was a mixture of intergranular, fatigue, and cleavage. It was also observed that the cleavage fracture was “bowed out” or serrated indicating that the intragranular γ/precipitates arrest the propagation of cracks. This and the change in fracture mode could be responsible for the lower creep rates and longer rupture lives. There was no evidence of grain boundary migration, change in grain size, or formation of “diamond” grains.

    Keywords:

    fatigue (materials), fatigue tests, creep rupture strength, stresses, crack propagation, tests


    Paper ID: STP38862S

    Committee/Subcommittee: E08.05

    DOI: 10.1520/STP38862S


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