Environmental effects on fatigue crack growth in 7075 aluminum alloy

A. Bonakdar, F. Wang, J. J. Williams, Nikhilesh Chawla

Research output: Contribution to journalArticlepeer-review

27 Scopus citations


The fatigue behavior of aluminum alloys is greatly influenced by the environmental conditions. In this article, fatigue crack growth rates were measured for 7075-T651 Al alloy under ultrahigh vacuum (UHV, ~10-10 Torr), dry air, and water vapor. Standard compact tension (CT) specimens were tested along the L-T orientation under various load ratios of 0.1, 0.5, and 0.8. Fracture surfaces and crack morphologies were studied using scanning electron microscopy and crack deflection analysis. The crack growth behavior under vacuum was affected by friction and possible rewelding of crack surfaces, causing an asymmetry in the crack growth behavior, from load shedding to constant load. The enhancement of crack growth at higher moisture levels was observed and is discussed in terms of moisture decreasing friction between the crack faces. The effect of crack deflection as a function of R ratio and environment is also presented.

Original languageEnglish (US)
Pages (from-to)2799-2809
Number of pages11
JournalMetallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
Issue number8
StatePublished - Aug 2012

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Metals and Alloys


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