Relationship between corrosion properties and heat treatment in aluminium alloys
This paper is an outcome of long-standing collaboration with industrial companies that had to address changes in corrosion properties in wrought aluminium alloys in relation to their microstructural condition. The decisive aspect for the microstructure was heat treatment. Four aluminium alloy grades (EN AW 2024; 5083; 6082; 7075) and several heat treatments were studied. The resulting mechanical properties and changes in corrosion behaviour were evaluated. The findings were correlated with the microstructural condition and the intermetallics found in the materials. This highlighted the effects of heat treatment on corrosion properties for the individual aluminium alloys of which an engineering designer should be aware as they alter the original condition substantially. In addition, the effects of the environment on the corrosion properties of selected aluminium alloys in terms of theoxonium cation activity were monitored. Based on the findings, recommendations were developed for use of aluminium alloys and their heat treatment for various basic or acidic environments.