A Micromechanistic Interpretation of Cyclic Crack-Growth Behavior in a Beta-Annealed Ti-6Al-4V Alloy

Abstract

The cyclic crack-growth resistance of a Ti-6Al-4V-0.20 w/o 0 alloy, originally mill annealed, is found to be improved significantly through beta annealing. This improvement is particularly pronounced below a transition point in the crack-growth behavior of the beta-annealed material, which occurs at a stress-intensity range Delta K = 23 MPa.(m to the 1/2 power). Below this point, the exponent in the growth rate law (da/dN = C(Delta K)to the m power) changes from approximately 3.1 (above) to 6.3 (below). Consequently, crack-growth rates da/dN below the transition point are reduced by as much as an order of magnitude below the levels determined for the mill-annealed condition at comparable Delta K levels. This reduction is due to crack bifurcation.

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Document Details

Document Type
Technical Report
Publication Date
Nov 24, 1976
Accession Number
ADA033874

Entities

People

  • George R. Yoder
  • L. A. Cooley
  • Thomas W. Crooker

Organizations

  • United States Naval Research Laboratory

Tags

Communities of Interest

  • Air Platforms

DTIC Thesaurus Topics

  • Classification
  • Crack Propagation
  • Cracks
  • Crystal Structure
  • Electron Microscopy
  • Heat Treatment
  • Materials
  • Mechanical Properties
  • Microscopes
  • Microscopy
  • Military Research
  • Resistance
  • Scanning Electron Microscopy
  • Stress Intensity Factors
  • Titanium
  • Titanium Alloys
  • Transitions

Readers

  • Analytical Mechanics
  • Materials Science (Mechanical Engineering).
  • Powder metallurgy of Titanium alloys.