Fatigue and corrosion behavior of in-service AA7075 aircraft component after thermo-mechanical and retrogression and re-aging treatments

Abstract

Fatigue crack growth and corrosion are the two important failure mechanisms for aircraft structural components and, therefore, various treatments have been developed to improve the fatigue and corrosion resistance of aircraft materials. In the present study, thermo-mechanical and retrogression and re-aging treatments were applied to AA7075T7352 specimens, which were extracted from a nearly 40 years in-service F-4 Phantom component. The in-service component was selected in order to observe the influence of thermo-mechanical and retrogression and re-aging treatments on the properties of a used aircraft material and it was expected that the service life of the material is extended in the maintenance stage. In the experimental work, electrical, mechanical, fatigue crack growth, and corrosion tests were carried out using the specimens with T7352 (as-received), thermo-mechanical and retrogression and re-aging conditions. Based on the results, fatigue crack growth resistance of the material benefited from the thermo-mechanical and retrogression and re-aging treatments; however, both treatments lowered the corrosion resistance of the material.