Influence of morphology of corrosion on fracture initiation in an aluminum alloy

Abstract

The image pertinent to the morphology of corrosion is an important feature that is essential for the purpose of evaluating the corrosive behavior of an aluminum alloy that finds selection and use in aircraft structural applications. Characteristic quantities pertinent to damage due to corrosion are extracted based on carefully executed, controlled and monitored experiments. The image processing technique was used to analyze the morphology of corrosion following exposure of an aluminum alloy to aggressive aqueous environment for different lengths of time. Parameters of Area-Box and surface corrosion ratio are introduced to describe the rule for the evolution of pitting corrosion. Based on the gray values for the different regions in an image, a three-dimensional (3-D) solid model was constructed in accordance with the damage data specific to pitting corrosion obtained from the experiments. A finite element analysis procedure was developed and used to predict the stresses and resultant site most susceptible for the onset of crack nucleation, or damage initiation, as a consequence of the pits resulting from exposure of the aluminum alloy to the aggressive environment.