Hot ductility behavior of an extruded 7075 aluminum alloy

The ductility behavior of an extruded 7075 aluminum alloy was studied using the tensile testing method in a wide range of temperatures (100-450 degrees C) and strain rates (10(-1)-10(-3) s(-1)). The mechanical behavior of the experimental alloy at high temperatures was also studied through hot compression testing method to explain the related deformation mechanisms. The results indicated that the ductility was monotonically increased by increasing deformation temperature. This was justified considering the fact that the volume fractions of the second phase particles might decrease at higher temperature thereby their detrimental effects on cavity nucleation and growth would be decreased. However, two regions were found where the general trend changed and the ductility decreased. The observed ductility drops at 350 degrees C/0.01, 0.001 s(-1) were attributed to the dynamic precipitation of Fe-rich secondary phases during deformation. The second ductility trough was observed at 450 degrees C/0.1 s(-1) and attributed to the occurrence of grain boundary sliding phenomena, which would facilitate the development of W-type or R-type cracks thereby reducing the ductility. (C) 2015 Elsevier B.V. All rights reserved.