Microstructure and its Relationship to Mechanical Properties in Equal Channel Angular Rolled Al6061 Alloy Sheets

Equal channel angular rolling (ECAR) is a severe  plastic deformation (SPD) technique which has been used to produce metal sheets with ultra-fine grain structure. In the present work, the relationships between the mechanical properties and microstructure of samples during the ECAR process have been investigated. The Rietveld method was applied to analyze the X-ray diffraction pattern and to determine the microstructural characteristics including the crystallite size, microstrain, and dislocation density. It was observed that the average crystallite size and dislocation density increased by increasing the strain during the ECAR process. The results showed that ECAR is a procedure intended to obtain meaningful structural refinement appearing in a crystallite. It can be justified by using Taylor equation that the mechanical properties are related to the dislocation density. The ECAR process strongly increases the yield strength and microhardness due to an increase in the dislocation density over a wide range of strain.