SYMPOSIA PAPER Published: 01 January 1988
STP23274S

Elevated Temperature Fatigue Crack Growth of Single Crystal René N4 Superalloy

Source

Constant-load-amplitude fatigue crack growth tests were conducted at 0.33 Hz over a temperature range of 538 to 871°C for single crystal René N4 nickel base superalloy. Crack growth behavior was found to be similar in the Paris law regime for the entire temperature range tested except for a slight increase in growth rate at 871°C at higher levels of the stress intensity range. Mainly, two distinct modes of fatigue fracture were observed, namely, a flat, featureless, Stage II fracture morphology and a faceted, crystallographic, Stage I cracking mode. The Stage II fatigue fracture occurred over the entire range of ΔK at the three highest temperatures. At 538°C, however, a transition from Stage II to Stage I fatigue fracture occurred with increase in ΔK. The higher crack growth rates at higher temperatures in the high-stress-intensity range were attributed to casting defects present in the material.

Author Information

Venkataraman, S
AFWAL MLLN, Wright-Patterson Air Force Base, OH
Nicolas, T
AFWAL MLLN, Wright-Patterson Air Force Base, OH
Khobaib, M
University of Dayton Research Institute, Dayton, OH
Price: $25.00
Contact Sales
Related
Reprints and Permissions
Reprints and copyright permissions can be requested through the
Copyright Clearance Center
Details
Developed by Committee: E08
Pages: 757–764
DOI: 10.1520/STP23274S
ISBN-EB: 978-0-8031-5036-2
ISBN-13: 978-0-8031-0949-0