The effect of solution aggressiveness on corrosion-induced mechanical properties degradation of aeronautical aluminum alloy 2198

The aim of the present work is to investigate the influence of different corrosive solutions on the corrosion degradation mechanism of Al-Cu-Li (2198) aluminum alloy. Exposure of tensile specimens was employed in three different corrosion solutions, namely exfoliation corrosion, 3.5 wt. % NaCl and Harrison's (diluted version) solution to study the corrosion-induced degradation of mechanical properties of the alloy. Additionally, macroscopical analysis of the surface deterioration was conducted for several exposure times. Tensile test results showed different corrosion behaviour for the three different corrosive solutions; specimens exposed to Harrison's solution exhibited the highest decrease as well as degradation rate of elongation at fracture (Af) even from the very short exposure times. Nevertheless, after 2160 h of exposure the Af decrease was stabilized. On the contrary, exposure to 3.5 wt. % NaCl solution showed the slowest degradation rate of elongation at fracture for the very short exposure times and up to 720 h, while essential degradation was noticed for higher exposure times with the property continuously decreasing with increasing exposure time. Severe localized attack was noticed in Harrison's solution, while corrosion attack in the other two solutions was found to be more homogeneously distributed on the specimen surfaces.