Investigation of Resistance of Intergranular Attack for Various Heat Treated 2011 Alloys After Hard Anodizing

The main alloying element of 2011 aluminum alloy is copper and it is disadvantageous from the point of corrosion compared to other aluminum alloys. 2011 alloy also contains bismuth and lead in their chemical composition. These elements have low melting point and enhance machinability of the alloy. In this way, 2011 alloys are frequently used in areas where machinability is important. Also, 2011 alloys are preferred in valve manufacture and therefore understanding its corrosion behavior is critical. In this study, 2011 aluminum billets were produced by direct chill (DC) casting and then homogenization was carried out. As the next step, billets were extruded. Different samples were taken from extruded profiles and heat treated to obtain T4, T6, T79, T73 conditions. Samples were then hard anodized. After anodizing, samples were taken to corrosive environment. Optical microscope, Scanning Electron Microscope (SEM) and Energy Dispersive Spectrometry (EDS) techniques were used for characterization and corrosion behavior of 2011 alloy under different heat treatment conditions was investigated. It was found that T6 condition, which is the most preferred heat treatment condition for 2011 alloys, has the maximum corrosion depth and other experimental results obtained agree well with expected properties.