Microstructural and mechanical properties of Al 7075 alloy processed by Equal Channel Angular Pressing

In this paper the effect of Equal Channel Angular Pressing (ECAP) on microstructures, mechanical properties of Al-7075 alloys has been investigated. Due to ECAP, tensile yield strength, ultimate tensile strength, and micro hardness of the material increase by 168%, 73%, and 93%, respectively. On the other hand, elongation to failure decreases. The quantum of decrease is high after the first pass while after the subsequent passes it remains almost constant. TEM analysis shows that the rod-like η1 (MgZn2) precipitates, present in the annealed condition, are broken in to small spherical particles during ECAP and are distributed uniformly throughout the material. The presence of these fine particles, combined with their uniform distribution is very effective in restricting grain growth resulting in ultrafine grains. Analysis of the deformation and fracture morphologies of ECAPed samples by scanning electron microscope (SEM) shows that the average dimple size gradually decreases with increasing number of ECAP passes.