Characterization of double aluminium alloy specimens after ECAP

The Equal Channel Angular Processing or pressing, i.e. the ECAP, allows to modify the properties of materials at the microstructure level. It consists in the induction of a high amount of shear deformation in the material that leads in general to a grain size refinement, a precipitate dispersion and a redistribution of dislocations depending on experiment conditions.The objective of the present investigation is to understand how the ECAP can influence the surface and the bulk mechanical properties of double aluminium alloy specimens. Each specimen was composed of a tubular part of the series AA6026 as well as of a cylindrical part of the series AA6012 assembled together before ECAP. A negligible bonding effect was observed after ECAP and after uniaxial compression tests performed at constant temperatures varying between 200 and 300°C with different press ram velocities. The characterization of each ECAP condition was initially represented in terms of the stress versus deformation flow curves. The load versus stroke curves were preferred due to the friction acting at the forming tool- specimen interface. It was obtained a decrease in the load versus stroke levels with increasing the number of ECAP passes under the experiment conditions of the present investigation. The increase in the press ram velocity determined an increase in the load for a given stroke.