No abstract

No abstract

No abstract

No abstract

No 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.

No abstract

Aluminum alloys are the first chosen materials for aircraft structures since 1930 due to their high ratio between properties and density. Currently, aircraft industries use Al-Zn-Mg-Cu alloys, with T7451 temper, which it shows high strength, fatigue and corrosion resistance. The improvements properties are result from the η’ phase formation, MgZn2. The aim the present work is to propose an alternative route for ageing heat treatment at one AA7050 aluminum alloy, the manner which the formation of η’ phase particles at lower temperatures and longer periods of treatment is obtained. According to the literature, ageing treatments at low temperatures and longer periods optimize the usage of the solution atoms, favoring the growth and nucleation particles. As a result, there is an increase in the density of the particle improving the alloy properties. These improvements show a decrease up to 13% in the crack propagation rate for moderate ΔK levels, keeping the same levels of Vickers hardness but with decay of 12% of ultimate tensile strength.