Quantification of corrosion mechanisms under immersion and salt-spray environments on an extruded AZ31 magnesium alloy

The corrosion mechanisms of pitting, intergranular, and general corrosion were examined on an extruded AZ31 magnesium alloy subjected to immersion and salt-spray environments. The three mechanisms were quantified using optical microscopy and laser profilometry for over 60 h of testing. Although both environments showed similar trends, the immersion environment was more deleterious with respect to intergranular and general corrosion. On the other hand, the salt-spray environment did allow deeper pits to form throughout the entirety of the experiments, which then led to a substantial thickness drop (general corrosion) compared with the immersion environment.

► Quantification of AZ31 corrosion mechanisms in two environments were obtained.
► General corrosion and surface characteristics were higher in the immersion environment.
► Pit characteristics, such as surface area and volume, were larger on the salt spray surfaces.
► The continuous presence of water affected the general corrosion and pit formation.
► The build-up of chloride ions affected pit growth on the salt spray surfaces.