Hot Deformation of AA6082 Containing Fine Intermetallic Particles

Hot deformation of AA6082 aluminum alloy was studied by compression tests carried out between 573 K and 823 K (300 °C and 550 °C) under a wide range of strain rates. Light optical and scanning electron microscopy were used to study the as-received microstructure, which consisted of elongated, partially recrystallized grains containing fine Mg₂Si and AlFeMnSi particles. The hot-deformed material showed the effects of dynamic recovery, i.e., small low angle grain boundary formation and dislocation pinning by fine particles. The flow data were used to calculate the constitutive equations, obtaining high values of n exponent. This behavior was attributed to the interaction of particles with dislocations during hot deformation. Threshold stresses were introduced to adjust the constitutive equation to a n exponent value of 5 at high stresses and a value of 3 in the low stresses range, which was related to dislocations’ climbing and sliding and thus to dynamic recovery. The threshold values were related to the detachment stresses in close connection with the precipitation state which was a function of the deformation temperature.