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Fatigue Crack Growth Resistance of Titanium Metal Matrix Composites

  • H. StanleyEmail author
  • M. Dear
  • T. J. A. Doel
  • P. Bowen
Conference paper
Part of the The Minerals, Metals & Materials Series book series (MMMS)

Abstract

Fatigue crack growth resistance has been assessed in continuous SCS-6 fibre reinforced Ti-6Al-4V composites from unbridged defects at room temperature, 300 and 450 °C in air and in vacuum. The initial applied stress intensity factor range (ΔKapp) (on the unbridged crack depth) was used to quantify the crack arrest/catastrophic failure (CA/CF) transitions for all test conditions. All tests were conducted at stress ratios of 0.1, 0.5 and 0.7 and at a frequency of 4 Hz. Fatigue crack growth tests revealed that increased temperature results in increased fatigue crack growth rates. The CA/CF transition reduced as the temperature increased from room temperature to 300 °C and to 450 °C. The CA/CF transition of the composite is greatly affected by the initial ΔKapp value due to its effect on fibre failures. Crack bifurcation appears to be a function of test piece geometry and not a function of test temperature or the initial ΔKapp value. Tests in vacuum demonstrate that fatigue crack growth rates are reduced. All cracks in vacuum grew in single mode I. Longer fibre pull out lengths were observed in tests performed in vacuum compared with air for similar conditions, especially during 0.5 mm of growth from the notch. These fibres are deduced to bridge the crack for a long time, suggesting that the fibres in the first few rows are important to reduce crack growth rates and to promote crack arrest.

Keywords

Fatigue crack growth Titanium metal matrix composites Temperature Environmental effects Crack arrest Fibre pull out 

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Copyright information

© The Minerals, Metals & Materials Society 2018

Authors and Affiliations

  • H. Stanley
    • 1
    Email author
  • M. Dear
    • 1
  • T. J. A. Doel
    • 1
  • P. Bowen
    • 1
  1. 1.School of Metallurgy and MaterialsThe University of BirminghamEdgbaston, BirminghamUK

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