SYMPOSIA PAPER Published: 01 January 1988
STP23242S

The Effect of Loading History on Closure Behavior in Rene' 95

Source

Experimental observations of closure in fatigue crack growth as a function of loading history are presented for a high-strength nickel-base superalloy, Rene' 95, at 649°C. Fatigue crack propagation (FCP) tests were conducted under either constant load amplitude (increasing ΔK) or under threshold load shedding (decreasing ΔK) test conditions. Closure loads were determined from load-offset displacement traces that were recorded with the aid of a crack mouth opening displacement extensometer. Plots of Kcl versus Kmax revealed that Kcl remained constant for both the constant load and decreasing load FCG tests, indicating that Kcl was not a consequence of the loading history. Similar plots for side-grooved specimens and smooth specimens revealed identical behavior, thus ruling out plasticity-induced closure as the operating closure mechanism.

Author Information

Zawada, LP
AFWAL/MLLN, Wright-Patterson Air Force Base, OH
Nicholas, T
AFWAL/MLLN, Wright-Patterson Air Force Base, OH
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Details
Developed by Committee: E08
Pages: 192–205
DOI: 10.1520/STP23242S
ISBN-EB: 978-0-8031-5036-2
ISBN-13: 978-0-8031-0949-0