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Orientation and temperature dependence of some mechanical properties of the single-crystal nickel-base superalloy Rene N4. II - Low cycle fatigue behaviorThe low cycle fatigue (LCF) properties of a single-crystal nickel-base superalloy Rene N4, have been examined at 760 and 980 C in air. Specimens having crystallographic orientations near the 001, 011, -111, 023, -236, and -145 lines were tested in fully reversed, total-strain-controlled LCF tests at a frequency of 0.1 Hz. At 760 C, this alloy exhibited orientation dependent tension-compression anisotropies of yielding which continued to failure. Also at 760 C, orientations exhibiting predominately single slip exhibited serrated yielding for many cycles. At 980 C, orientation dependencies of yielding behavior were smaller. In spite of the tension-compression anisotropies, cyclic stress range-strain range behavior was not strongly orientation dependent for either test temperature. Fatigue life on a total strain range basis was highly orientation dependent at 760 and 980 C and was related chiefly to elastic modulus, low modulus orientations having longer lives. Stage I crack growth on 111 planes was dominant at 760 C, while Stage II crack growth occurred at 980 C. Crack initiation generally occurred at near-surface micropores, but occasionally at oxidation spikes in the 980 C tests.
Document ID
19860065584
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Gabb, T. P.
(NASA Lewis Research Center Cleveland, OH, United States)
Gayda, J.
(NASA Lewis Research Center Cleveland, OH, United States)
Miner, R. V.
(NASA Lewis Research Center Cleveland, OH, United States)
Date Acquired
August 12, 2013
Publication Date
March 1, 1986
Publication Information
Publication: Metallurgical Transactions A - Physical Metallurgy and Materials Science
Volume: 17A
ISSN: 0360-2133
Subject Category
Metallic Materials
Accession Number
86A50322
Distribution Limits
Public
Copyright
Other

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