A microscopic study on the corrosion fatigue of ultra-fine grained and conventional Al–Mg alloy

•Corrosion fatigue was investigated for an ultra-fine grained and conventional 5083 alloy.•Pit initiation, pit location and crack propagation were investigated.•In air, the ultra-fine grained alloy had superior fatigue performance compared to conventional 5083 alloy.•At low maximum stress, the ultra-fine grained alloy is more susceptible to fatigue by pitting.•At high maximum stress, slip enhanced dissolution is the dominant mechanism or the ultra-fine grained alloy.

The corrosion behavior of a nanocrystalline (NC)/ultrafine grained (UFG) Al–Mg based alloy was investigated and compared to its conventional counterpart 5083(H111). The corrosion fatigue (CF) was studied with respect to pit initiation, pit location and crack propagation as a function of environment. Scanning electron microscopy (SEM) with EDS was used to analyze the fracture surface of the failed specimen with respect to pitting characteristics, crack propagation and corrosion product. Load vs. cycles to failure was measured and S/N curves were generated for the UFG Al–Mg based alloy and the conventional counterpart 5083 in air and seawater.