STP942

    Thermal Fatigue Testing of Coated Monocrystalline Superalloys

    Published: Jan 1988


      Format Pages Price  
    PDF Version (520K) 20 $25   ADD TO CART
    Complete Source PDF (27M) 20 $271   ADD TO CART


    Abstract

    Induction heating of stepped-disk specimens to study thermal fatigue of coated superalloys is well suited for studying anisotropic alloys and is easily adaptable for corrosive or inert atmosphere testing. Details of the experimental apparatus and results of a thermoelastic finite element analysis to find the stress-strain history are given.

    To illustrate the technique, the effect of cyclic thermal strains on the durability of an aluminide coating applied to a typical monocrystalline nickel-base superalloy was studied in air. Results show that both the compressive strain encountered on specimen heatup and the tensile strain encountered on cooldown critically affect the aluminide coating degradation. After 6000 cycles of heating from 520 to 1080°C in 5 s, followed by 30 s cooling, 80% coating penetration by scalloping was observed. A similar treatment with 6 s cooling resulted in alumina-filled “cracks” extending into the substrate.

    Keywords:

    thermal fatigue, induction heating, stepped-disk specimen, aluminide coating, monocrystalline, nickel-base, superalloy, René N4, finite element


    Author Information:

    Holmes, JW
    Graduate Student, Massachusetts Institute of Technology, Cambridge, MA

    McClintock, FA
    Professor and Undergraduate Student, Massachusetts Institute of Technology, Cambridge, MA

    O'Hara, KS
    Metallurgist, General Electric Company, Lynn, MA

    Conners, ME
    Professor and Undergraduate Student, Massachusetts Institute of Technology, Cambridge, MA


    Paper ID: STP24514S

    Committee/Subcommittee: E08.05

    DOI: 10.1520/STP24514S


    CrossRef ASTM International is a member of CrossRef.