Intergranular corrosion of AA 5083 - H321 aluminum alloy

The 5083 alloy H321 temper is one of the most common alloy used in marine environments due to intergranular corrosion resistance in seawater. When the local concentration of Mg is high enough, beta (β) phase (Al 3Mg2) forms in order to lower the stored energy in the material. The β phase is anodic to the matrix of alloy in seawater and this potential difference provides the driving force for dissolution of the β from the grain boundaries causing intergranular corrosion (IGC). Influence of rolling and annealing parameters on the intergranular corrosion was studied by ASTM G67 Standard Test-Nitric Acid Mass Loss (NAMLT), using optical microscopy (OM), scanning electron microscopy (SEM) and energydispersive X-ray spectroscopy. Results show an increase of the amount of the Al xFeyMnz and Al3Mg2 particles along the grain boundary when the annealing temperature is maintained at 260°C and at slow cooling, seeing a high resistance to intergranular corrosion. © 2009 Universitatea Politehnica Bucuresti.