Marine atmospheric corrosion of Al-Mg joints by friction stir blind riveting

•Marine atmospheric corrosion of Al-Mg FSBR joints was investigated.•Severe corrosion on Mg (not in crevice region) was found due to general and galvanic corrosion.•Al corroded in the coupled region near the rivet with the formation of gibbsite.•Al corrosion was caused by the alkaline environment generated by cathodic reaction.•The highly alkaline environment passivated Mg deep inside the crevice.

This paper investigated the atmospheric corrosion behavior of Al-Mg friction stir blind riveting joints exposed at a severe marine test environment. Besides the severe corrosion that occurred on Mg alloy AZ31B-H23, Al alloy 5754-O also corroded in the coupled region because of the alkaline condition generated by the cathodic reaction inside of the crevice. The highly alkaline environment, however, passivated Mg deep inside the crevice. The corrosion products on Mg were identified as magnesium carbonates and that on Al was mainly gibbsite, which was an unusual corrosion product of Al exposed to atmospheric conditions.