Effect of environment's aggressiveness on the corrosion damage evolution and mechanical behavior of AA 2024‐T3

Abstract

The aim of this work is to contribute on establishing correlations between corrosion damage from accelerated laboratory corrosion tests of varying aggressiveness; by accounting for both, the metallographic features of corrosion damage and the mechanical properties of the corroded material. The work is based on the investigation of corrosion damage caused by the exposure of 2024‐T3 aluminum alloy to 3.5% NaCl solution, which is presently considered to properly represent in‐service exposure. Corrosion damage evolution was quantified for periods ranging between 500 and 3000 hours by evaluating pitting density, depth, and diameter. It was compared to available results of corrosion damage of the same alloy subjected to exfoliation corrosion test. Furthermore, the tensile properties of precorroded material in each solution were evaluated. The results allow the formulation of correlation functions between corrosion damage geometrical metallographic features from low‐ to high‐aggressiveness environment exposures. On the other hand, the degradation of tensile properties, and particularly of tensile ductility, is more pronounced in specimens exposed to higher corrosion rate environments, even when damage in both environments leads to equivalent metallographic features. This suggests significant differences in the underlying physical mechanisms of the damage accumulation process when the same material is exposed to different corrosive solutions. This work suggests the need to expand current corrosion damage interpretation, to account not only for geometrical metallographic features but also for mechanical properties of the affected material.

Numerical Simulation of Tensile Behavior of Corroded Aluminum Alloy 2024 T3 Considering the Hydrogen Embrittlement

“…With distancing of the affected layer, and approaching the characteristics of the raw material, load carrying capacity is restored and the maximum depth of penetration decreases, leading to increased nanoindentation hardness values. However, the HEDE mechanism alone does not seem sufficient to explain all the effects of HE observed in previous works, such as the presence of a quasi-cleavage zone in tensile fracture surfaces or the decrease in strain of corroded specimens [2][3][4][5][6]21,23]. Most likely, a combination of different mechanisms is responsible for these results, with the need of more experimental observations to fully characterize the main acting mechanism.…”

“…Only a few concepts were reported, aiming to directly correlate the metallographic features, which characterize corrosion damage of a material to the resulting degradation of its mechanical properties. Such a correlation is not an easy task, as the term "corrosion damage" is in the first place, a qualitative term, which needs to be first related to specific and measurable material features in order to be quantified and, in addition, the evolution of these features follows usually non-linear time functions [5][6][7]. In [8], a correlation between the metallographic features of corrosion damage developed on the magnesium alloy AZ31 and the mechanical properties of the corroded material has been made manageable by using artificial neural networks.…”

Simulation of the corrosion-induced damage on aluminum alloy 2024 specimens with equivalent surface notches

“…% NaCl solution, with pitting density, depth and shape evolving with exposure time. Vasco et al [32] performed correlations between corrosion damage from accelerated corrosion tests of varying aggressiveness by accounting for both, the metallographic features of corrosion damage and the mechanical properties of the corroded material. Correlations regarding geometrical metallographic features were found under dominance of pitting corrosion and up to 8 hours in EXCO solution; higher variations after the occurrence of pit coalescence and transition to dominance of exfoliation corrosion were presented.…”