Conjoint influence of equal channel angular pressing and annealing on microstructure and mechanical properties of aluminum alloy 7075

The effect of equal channel angular pressing combined with inter-pass and post-process annealing on the microstructure and mechanical properties of the Al-7075 alloy has been studied. The samples underwent successful equal channel angular pressing for three passes using the Bc route. The most significant changes in mechanical properties were observed after the first pass. Despite an 88 % reduction in grain size, the hardness of the alloy increased by 45 % and the fracture toughness decreased by 75 %. Post-process annealing was found to be an effective method for enhancing the alloy's toughness. Annealing the one-pass sample at 310 degrees C resulted in a 33 % increase in fracture toughness; from 15.8 J to 21.02 J. Inter-pass annealing had a lesser impact on improving fracture toughness compared to post-process annealing. It can be concluded that a balanced combination of strength and toughness can be achieved by utilizing a combination of equal channel angular pressing and inter-pass or post-process annealing. Examination of the fracture surfaces of the samples revealed intragranular fractures, with the annealed samples exhibiting higher energy absorption during impact and better toughness compared to the non-annealed sample. Applying the equal channel angular pressing in multiple passes, conducting annealing heat treatment between passes and after the final pass, and evaluating the mechanical properties of the final sample through micro-hardness and fracture tests. image