Effects of Potential and Anisotropy of Material on Mode II Fatigue Crack Growth of 7075-T6 Aluminum Alloy in 3.5% Saltwater

Abstract

The characteristics of mode II fatigue crack growth were investigated in air and in 3.5% saltwater on 7075-T6 aluminum alloy specimens extracted in the L-T and T-L orientations. The tests in saltwater were made under free corrosion and under application of anodic and cathodic potentials.
The mode II crack growth rates in saltwater were higher than those in air, regardless of the applied potential, in the higher ΔK_II region for L-T orientation. Almost no effect of saltwater and applied potential was found in the da/dN-ΔK_II relation for T-L orientation. A comparison between the behaviors of mode II and mode I fatigue crack growth was also made.