FATIGUE BEHAVIOR OF 8090-AL-LI ALLOY IN CHLORIDE-CONTAINING ENVIRONMENTS

The effect of an environment containing chloride on the fatigue behavi our of a 8090 Al-Li-Mg-Cu alloy was studied. Results were compared wit h those obtained on a traditional 2024 Al-Cu-Mg alloy. Fatigue and cor rosion-fatigue tests were carried out both on smooth specimens and riv eted samples. In order to assess the corrosion behaviour of the materi als and their susceptibility to stress corrosion cracking, potentiodyn amic polarization and slow strain rate tests were carried out. Results showed a remarkable effect of the aggressive environment on the fatig ue behaviour both of the innovative 8090 alloy (in T8 ageing condition s) and on the traditional clad 2024 alloy (in T3 natural ageing condit ions), though the former showed slightly better behaviour. Nevertheles s, in the presence of rivets the reduction in fatigue strength in the aggressive environment was negligible. Slow strain rate tests showed p remature fractures under anodic polarization above the pitting potenti al and with a strain rate of 10(-6) s(-1), only for the 8090 T8 alloy.