Influence of microstructure and load ratio on fatigue threshold behavior in 7075 aluminum alloy

✍ Scribed by S.E Stanzl-Tschegg; O Plasser; E.K Tschegg; A.K Vasudevan

• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 612 KB
• Volume: 21
• Category: Article
• ISSN: 0142-1123
• DOI: 10.1016/s0142-1123(99)00096-1

✦ Synopsis

The influence of microstructure and load ratio on fatigue crack propagation in the near-threshold regime has been investigated on the 7075-aluminum alloy. The alloy heat treatment was varied to give underaged and overaged microstructures with approximately the same yield strength properties. Crack growth measurements were performed at constant load ratios between R=Ϫ1 and +0.8 in ambient air. The influence of load ratio is discussed in terms of deformation slip, crack branching and fracture mode.

Vacuum data from the literature are compared with the current air results. For both environmental conditions, it was observed that the crack growth and threshold properties of the underaged alloy were better than the overaged alloy. The overall fatigue behavior is discussed in terms of the two parameter concept namely ⌬K and K max .