Effect of salt-water fog on fatigue crack nucleation of al and al-li alloys

Abstract

Fatigue and corrosion-fatigue tests were performed to quantify the fatigue properties of AA2524-T3 and AA2198-T851 Al alloys. High cycle axial fatigue tests were carried out under air and salt-water fog conditions. In air, the specimens were fatigue tested at a frequency of 50 Hz, using specimens with and without preconditioning in a salt spray chamber, and for the corrosion fatigue condition, the tests took place at a frequency of 30 Hz in a salt-water fog condition. In all cases it was used a sinusoidal waveform and a stress ratio (R) of 0.1. The results indicate that the saline environment had a deleterious effect on the fatigue life of the two aluminum alloys. AA2524-T3 exhibited a better fatigue strength than AA2198-T851 when fatigue tested in air. However, considering the corrosion fatigue test in a saline fog environment an inverse behavior was observed with the AA2198-T851 exhibiting higher fatigue strength.