An investigation on the effect of crystal orientation on corrosion behaviour of ECAP processed Aluminium 7075 alloy

In recent years, Equal Channel Angular Pressing (ECAP) has attracted a lot of attention as a novel method in implementing strain. In this study, the effect of crystallographic orientations on corrosion behaviour of aluminium 7075 alloy was studied. ECAP was used to provide samples with a textural microstructure form. The samples were cut in 0°, 22.5°, 45°, 67.5° and 90° angles to obtain the corrosion characteristics of varying surfaces. Polarization and EIS tests were performed to study the corrosion behaviour of the samples. XRD TEXTURE analysis was performed to verify crystallographic orientations of the samples along with the relation between the crystallographic orientations and the corrosion characteristics. Results showed that the structure was greatly influenced by the ECAP process. Corrosion verifications demonstrated that, when the surface were created at 0° cutting angle, corrosion potential for two pass pressed sample was more positive than the sample which was pressed once. However, in case of surfaces created by cutting angles of 22.5°, 45°, 67.5° and 90°, the corrosion potential of one pass pressed samples was more than two pass pressed counterparts. The dependence of the corrosion behaviour of samples on different cutting angles was explained by the XRD TEXTURE analysis results.

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