Accession Number:

ADA052586

Title:

Microstructural Effects and Fatigue Life Predictions of Notched and Un-notched Nickel Base Superalloys at Elevated Temperatures.

Descriptive Note:

Interim rept. 1 Jan-31 Dec 77,

Corporate Author:

CINCINNATI UNIV OHIO DEPT OF MATERIALS SCIENCE AND METALLURGICAL ENGINEERING

Personal Author(s):

Report Date:

1978-02-01

Pagination or Media Count:

38.0

Abstract:

The low cycle fatigue LCF of Rene 80 has been investigated at 1400, 1600 and 1800 F. Emphasis has been placed on the 1800 F studies using smooth bar continuous cycling and 90 sec hold time and notch LCF specimens. The detailed transmission electron microscopy shows that at 1600 and 1800 F the dislocation debris is independent of test rate over two orders of magnitude. The test results can not be explained in terms of the conventional approaches to high temperature LCF for which damage is assumed to result from creepfatigue interactions. Instead, it is suggested that the important damage mechanism is an interaction between the deformation mode and the environment. Based on that understanding a model is developed for crack propagation at elevated temperatures and a similar model is being developed for crack initiation. Author

Subject Categories:

  • Properties of Metals and Alloys

Distribution Statement:

APPROVED FOR PUBLIC RELEASE