Microstructural development during hot forging of Al 7075 powder

The present investigation deals with the microstructural evolution attained during hot forging of Al 7075 prealloyed powders at various temperatures and strains. Preforms were fabricated by uniaxial compaction at 350 MPa followed by sintering at 610 degrees C for 40 min in nitrogen atmosphere. Sintered preforms were subsequently hot forged at various temperatures (0.6, 0.7, 0.8 and 0.9 T-m) and under various strains (0.51, 0.92 and 1.14). The effect of strain at various forging temperatures on the particle morphology, interparticle porosity, prior particle boundary (oxide layer) and hardness has been investigated. It was observed that a temperature of 0.8 T-m and a true strain of 0.92 is required for the disruption of oxide layer during hot forging of the powder preforms. The hardness values reveal that the strain of 0.92 is sufficient for optimum deformation and consolidation of the particles even at lower forging temperatures of 0.6 T-m. (C) 2015 Elsevier B.V. All rights reserved.