Strengthening of AA5052 aluminum alloy by equal channel angular pressing followed by softening at room temperature

Effects of equal channel angular pressing (ECAP) on the microstructure and tensile properties of AA5052 aluminum alloy was investigated. XRD analysis showed that the maximum dislocation density was achieved after 4 passes ECAP and reduced with further deformation which was in line with formation of ultrafine grain structure with a high fraction of high angle grain boundaries (HAGBs). Increasing dislocation density in 4 passes deformed specimen resulted in increasing hardness, yield strength (YS) and ultimate tensile strength (UTS). With 6 passes ECAP, the hardness and YS were not changed while the UTS was further increased. Unchanged values of hardness and YS were attributed to the reduction of dislocation density and simultaneous formation of ultrafine grain structure. Room temperature softening was observed in the severely deformed samples and consequently, YS reduces, UTS remains unchanged and ductility and toughness improve significantly.