Mechanical and corrosion properties of AA5083 alloy sheets produced by accumulative roll bonding (ARB) and conventional cold rolling (CR)

Abstract

Influence of accumulative roll bonding (ARB) and conventional cold rolling (CR) on the mechanical and corrosion properties of AA5083 alloy sheets has been studied. Tensile tests showed significant increase in strength and a decrease in elongation after each ARB deformation and cold rolling reductions. Results of nitric acid mass loss test (NAMLT) revealed that cold rolled and ARB processed specimens were resistant toward intergranular corrosion (IGC) in as-deformed state. However, after 7 days of sensitization at 100 and 150 degrees C, cold rolled material became IGC sensitive, while ARB specimens stayed IGC resistant. IGC susceptibility can be correlated with different morphology and distribution of -phase (Mg2Al3) precipitated during sensitization. It was found that extensive shear banding contributed a favorable distribution of -phase precipitates in the structure of IGC resistant ARB processed specimens. In case of IGC susceptible conventionally cold rolled specimens, large amount of -phase precipitated preferentially along the elongated grain boundaries. Electrochemical parameters were in a good correlation with the results of NAML tests, which in turn, confirmed the superiority of ARB multilayered structure over conventional cold rolled structure in terms of IGC susceptibility and corrosion stability.