Effect of Equal Channel Angular Extrusion on the Microstructures and Properties of Two Extruded Al-Mg-Si Alloys

The effect of equal channel angular extrusion (ECAE) on the microstructure of two Al-Mg-Si extrusion alloys wasinvestigated by high resolution electron backscattered diffraction (EBSD) using a field emission gun scanning electronmicroscope (FEG-SEM) and a transmission electron microscope (TEM). Two contrasting alloys: a dilute alloy, basedon alloy 6061 and a concentrated alloy, based on alloy 6069 were employed for this research. It has been foundthat prior ECAE to extrusion promotes high angle grain boundaries (HAGBs) in the extrusions, and the increase inHAGBs ratio is due to the large shear deformation involved in the process of ECAE. Tensile testing results show thata further ageing treatment strengthens the alloys after extrusion and the ECAE processed extrusions are more ductilethan conventional extrusions.