Effect of Environmental Factors on the Determination and Quantification of Corrosion Modes in AA7075

Multiple modes of corrosion can occur simultaneously in a given environment, however generally, corrosion damage accumulation models only account for one type of corrosion (e.g. pitting or intergranular, but not both.). This work seeks to determine which modes of corrosion manifest under different environmental conditions and how they evolve with time. Furthermore, this study aims to quantify all forms of corrosion present for use in the development of a comprehensive damage accumulation model. In order to achieve this, AA7075-T651 (a structural aerospace alloy, Al-5.6Zn-2.5Mg-1.6Cu) samples were constantly immersed in solutions of varying pH, chloride concentration and temperature and serially removed after 1 hr, 1 day, and 1 month exposure time. These samples were then assessed by scanning electron microscopy, optical microscopy, and optical profilometry to characterize the types and extent of corrosion present.