The AA5XXX family of alloys is widely used alloys for marine application. However these alloys are
susceptible to intergranular corrosion (IGC) at high temperatures when they experience significant
thermal cycling. In this work we investigated the effect of constant thermal exposure and thermal cycling
on corrosion performance of these alloys. AA5456 and AA6061 alloys were also studied along with
AA5083 alloys with different temper designation O, H116 and H321 for comparative purpose. ASTMG67
tests were conducted on the heat treated alloys to measure their susceptibility to intergranular
corrosion. Constant exposure tests showed a steady rise in mass loss with the increase of thermal
exposure time. Thermal cycling tests were also carried out by exposing the samples at 43°C and 70°C for
different numbers of cycles. It was observed that samples exposed at 70°C were susceptible to
intergranular corrosion. However, no such evidence of intergranular corrosion was observed for those
samples exposed at 43°C. In addition mass loss test results for thermally exposed samples at constant
temperature were compared with the corrosion behavior of cyclically exposed alloy samples.
Keywords: AA5XXX alloys , intergranular corrosion, ASTM-G67 test