SYMPOSIA PAPER Published: 01 January 1996

Thermomechanical Fatigue Behaviour of Coated and Bare Nickel-Based Superalloy Single Crystals


The thermal-mechanical fatigue behaviour of chromium-aluminium coated [001] single crystals of AM1, a nickel-base superalloy for turbine blades, is studied using a “diamond” shape cycle from 600‡ to 1100‡C. Comparison with bare specimens does not show any significant difference in thermal-mechanical fatigue nor in isothermal low cycle fatigue at high temperature. Metallographic observations on fracture surfaces and longitudinal sections of specimens tested to fatigue life or to a definite fraction of expected life have shown that the major crack tends to initiate from casting micropores in the sub-surface area very early in bare and coated specimens, under low cycle fatigue or thermal-mechanical fatigue. But the interaction between oxidation and fatigue cracking seems to play a major role. A simple model proposed by Reuchet and Rémy has been identified for this single crystal superalloy. Its application to the life prediction under low cycle fatigue and thermal-mechanical fatigue for bare and coated single crystals with different orientations is shown.

Author Information

Chataigner, E
Remy, L
Centre des Matériaux P.M. FOURT E.N.S.M.P., EVRY, FRANCE
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Developed by Committee: E08
Pages: 3–26
DOI: 10.1520/STP16443S
ISBN-EB: 978-0-8031-5325-7
ISBN-13: 978-0-8031-2001-3