SYMPOSIA PAPER Published: 01 January 1988
STP24514S

Thermal Fatigue Testing of Coated Monocrystalline Superalloys

Source

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.

Author Information

Holmes, JW
Massachusetts Institute of Technology, Cambridge, MA
McClintock, FA
Massachusetts Institute of Technology, Cambridge, MA
O'Hara, KS
General Electric Company, Lynn, MA
Conners, ME
Massachusetts Institute of Technology, Cambridge, MA
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Details
Developed by Committee: E08
Pages: 672–691
DOI: 10.1520/STP24514S
ISBN-EB: 978-0-8031-5035-5
ISBN-13: 978-0-8031-0944-5