Vacuum Levels Needed to Simulate Internal Fatigue Crack Growth in Titanium Alloys and Nickel-base Superalloys: Thermodynamic Considerations

Abstract

Prior studies have examined fatigue growth of surface cracks in vacuum to simulate sub-surface growth in Ti-alloys and Ni-base superalloys. Even with the highest vacuum level attained using "state-of-the-art"pumps, it is unclear if conditions of internal crack growth are truly simulated. We consider thermodynamics of the oxidation process to help answer this question. This consideration helps explain a previously reported anomalous behavior of longer life in air than in vacuum under certain material/ test conditions

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Document Details

Document Type
Technical Report
Publication Date
Mar 01, 2012
Accession Number
ADA559012

Entities

People

  • James M. Larsen
  • V. Sinha

Organizations

  • Air Force Research Laboratory

Tags

Communities of Interest

  • Air Platforms

DTIC Thesaurus Topics

  • Air Force
  • Air Force Research Laboratories
  • Alloys
  • Crack Tips
  • Engineering
  • Equations
  • Fatigue Life
  • Governments
  • Manufacturing
  • Materials
  • Materials Science
  • Mechanics
  • Metals
  • New York
  • Thermodynamics
  • Titanium
  • Titanium Alloys

Readers

  • Materials Science (Mechanical Engineering).
  • Powder metallurgy of Titanium alloys.
  • Theoretical Analysis.