Fatigue crack growth behavior of PWA 1484 single crystal superalloy at elevated temperatures

Journal Article · Mon Apr 01 04:00:00 EST 1996 · Journal of Engineering for Gas Turbines and Power

DOI:https://doi.org/10.1115/1.2816603· OSTI ID:244714

Telesman, J ^[1]; Ghosn, L J ^[2]

---

1. NASA Lewis Research Center, Cleveland, OH (United States)
2. Case Western Reserve Univ., Cleveland, OH (United States)

A study was done to determine the fatigue crack growth behavior of a PWA 1484 single-crystal nickel-base superalloy in a temperature range of 427 C to 871 C. Two distinctive failure modes were observed, which were a function of both temperature and frequency. At lower temperatures and higher frequencies crack growth occurred on the {l_brace}111{r_brace} octahedral slip planes at an oblique angle to the loading direction. Higher temperatures and decrease in frequencies favored a Mode I type failure process. The failure mode transitions were explained by invoking arguments based on environmental damage mechanisms. The fatigue crack growth rate data were analyzed using three different crack driving force parameters. The parameters investigated consisted of the Mode I stress intensity parameter corrected for the inclined crack trajectory, and two different octahedral Mode II parameters, which are based on the calculation of resolved shear stresses on the {l_brace}111{r_brace} slip systems. The Mode I {Delta}K parameter did a fair job in correlating the data but did not collapse it into a single narrow band. The two octahedral crack driving force parameters, {Delta}K{sub RSS} and a newly proposed {Delta}K{sub OCT}, collapsed all the data into a single narrow band. In addition to correlating the fatigue crack growth rates, the two octahedral parameters also predicted the {l_brace}111{r_brace} planes on which the crack growth took place.

• OSTI ID: 244714
• Report Number(s): CONF-950629--
• Journal Information: Journal of Engineering for Gas Turbines and Power, Journal Name: Journal of Engineering for Gas Turbines and Power Journal Issue: 2 Vol. 118; ISSN 0742-4795; ISSN JETPEZ
• Country of Publication: United States
• Language: English

Related Subjects

33 ADVANCED PROPULSION SYSTEMS
36 MATERIALS SCIENCE
CRACK PROPAGATION
FAILURES
FATIGUE
FORECASTING
HEAT RESISTING ALLOYS
NICKEL BASE ALLOYS
SERVICE LIFE