Establishing first order correlations between pitting corrosion initiation and local microstructure in AA5083 using automated image analysis

A rapid image segmentation and correlation-based approach to investigating the local microstructural effects on pitting corrosion susceptibility is introduced. The impact of four different microstructural features, consisting of grain orientation, proximity to grain boundaries, proximity to intermetallic particles, and local geometrically necessary dislocation (GND) density, on pitting initiation in the 5083 aluminum alloy was directly investigated using automated pit detection processing in combination with electron microscopy-based characterization. Three different thermomechanical treatments were used to vary the system microstructure and samples were immersed in 3.5 wt% NaCl aqueous solution for 24 h to induce pitting. GND density and proximity to intermetallic particle both showed positive correlations, while grain orientation and proximity to grain boundary showed no correlation with pit initiation sites.

Automated summary

The study showed that there is a positive correlation between geometrically necessary dislocation (GND) density and proximity to intermetallic particles with pit initiation sites in 5083 aluminum alloy, while grain orientation and proximity to grain boundary have no correlation with pit initiation sites.