STP520: Thermal-Mechanical Fatigue Crack Propagation in Nickel- and Cobalt-Base Superalloys Under Various Strain-Temperature Cycles

    Rau, CA
    Group leader, and senior research associate, Materials Engineering and Research Laboratory, Pratt & Whitney Aircraft, Middletown, Conn.

    Gemma, AE
    Senior turbine structural engineer, Pratt & Whitney Aircraft, East Hartford, Conn.

    Leverant, GR
    Group leader, and senior research associate, Materials Engineering and Research Laboratory, Pratt & Whitney Aircraft, Middletown, Conn.

    Pages: 13    Published: Jan 1973


    Abstract

    Crack propagation rates under isothermal and thermal fatigue cycling have been determined for a conventionally-cast cobalt-base superalloy, and conventionally-cast and directionally-solidified nickel-base superalloys. Linear elastic fracture mechanics, where the crack growth rates under different strain ranges or for various crack lengths depend only on the strain intensity factor range, was found to be applicable over the range of crack growth rates of most practical importance. A comparison of crack growth rates is made for thermal fatigue under various strain-temperature cycles and isothermal low-cycle fatigue, and the influence of coatings and superimposed creep is discussed.

    Keywords:

    fatigue (materials), thermal fatigue, stresses, strains, coatings, crack propagation, cobalt containing alloys, nickel containing alloys, fracture properties, cycles


    Paper ID: STP38838S

    Committee/Subcommittee: E08.05

    DOI: 10.1520/STP38838S


    CrossRef ASTM International is a member of CrossRef.