Influence of environment on response characteristics of a high-strength aluminum alloy

Abstract

This paper presents the results of a study aimed at understanding the stress corrosion cracking behavior of aluminum (Al) alloy 2219 with specific reference to understanding the mechanisms governing initiation of cracks and their progressive growth through the alloy microstructure. The influence of stress level on the initiation of stress corrosion cracks was determined. Results of this study revealed pitting to be the main type of corrosion that occurred during the early stages of exposure of the chosen aluminum alloy to an acidic environment. After the formation and presence of a pit, the applied stress was found to induce local stress concentration, promoting the early initiation of one or more microscopic cracks, while concurrently enabling fine microscopic cracks to expand and grow through the alloy microstructure. The cracks were observed to propagate along the grain boundaries, with few of the cracks growing through the crystals. With appropriate selection of electrochemical parameters, the influence of applied stress, coupled with the use of a solid mechanics module in synergism with an electrochemical corrosion module, on the stress corrosion behavior of the chosen aluminum alloy 2219 was studied using an iterative approach, and numerical prediction of corrosion was made possible.