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

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 creep/fatigue 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)

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Document Details

Document Type
Technical Report
Publication Date
Feb 01, 1978
Accession Number
ADA052586

Entities

People

  • Stephen D. Antolovich

Organizations

  • University of Cincinnati

Tags

Communities of Interest

  • Biomedical
  • C4I
  • Energy and Power Technologies

DTIC Thesaurus Topics

  • Air Force
  • Alloys
  • Crack Propagation
  • Crystal Structure
  • Electron Microscopy
  • Engineering
  • Fatigue Life
  • Heat Energy
  • Heat Treatment
  • High Temperature
  • Materials
  • Materials Science
  • Strain Rate
  • Stress Strain Relations
  • Students
  • Superalloys
  • Transmission Electron Microscopy

Readers

  • Mechanical Engineering/Mechanics of Materials.
  • Powder metallurgy of Titanium alloys.

Technology Areas

  • Microelectronics