STP1263

    Thermo-Mechanical Fatigue of the Monocrystalline Nickel-Base Superalloy CMSX-6

    Published: Jan 1996


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    Abstract

    Total strain-controlled thermo-mechanical fatigue (TMF) tests were performed between 600 and 1100‡C on as-grown near to [001]-orientated specimens of the γ′ precipitate-strengthened monocrystalline nickel-base superalloy CMSX-6. The strain-temperature cycle (in-phase, out-of-phase, diamond) has a strong influence on the mechanical and microstructural events occurring during TMF. For given temperature intervals, the fatigue lives were shortest for out-of-phase tests and longest for in-phase tests, respectively. For all cycle shapes applied, the maximum tensile stress level was concluded to be the lifetime-limiting factor. The failure mode of the investigated alloy depends also on the conducted strain-temperature history. While strongly localized crystallographic shearing along {111} planes was dominant for in- and out-of-phase cycling, creep-induced damage occurred in diamond cycle tests. The evolution and coarsening of the microstructure were also studied. The latter is compared with the formation of stress-, strain- and diffusion-induced coarsened raft-like structures found in creep testing of similar materials.

    Keywords:

    single crystal, cyclic softening/hardening behaviour, nickel-base superalloy, low-cycle fatigue, thermo-mechanical fatigue, microstructure, rafting, fatigue life, fatigue damage


    Author Information:

    Kraft, SA
    Research Associate and Professor, Institut für Werkstoffwissenschaften, Lehrstuhl I, UniversitÄt Erlangen-Nürnberg, Erlangen,

    Mughrabi, H
    Research Associate and Professor, Institut für Werkstoffwissenschaften, Lehrstuhl I, UniversitÄt Erlangen-Nürnberg, Erlangen,


    Paper ID: STP16444S

    Committee/Subcommittee: E08.06

    DOI: 10.1520/STP16444S


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