Tensile Behavior and Microstructure Evolution of an Extruded 6082 Aluminum Alloy Sheet at High Temperatures

The hot tensile behavior of an extruded 6082 alloy sheet at varying temperatures and strain rates was investigated by a Gleeble3500 thermal simulation testing machine. The optical microscope (OM), scanning electron microscope (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) were applied to observe the microstructure evolution. It is found that the flow stress of the studied alloy declines with increasing deformation temperature. When deformed at high temperatures, the density of dislocation decreases obviously. In addition, precipitate coarsening occurs, resulting in a decrease in deformation resistance. The dimple number of the fracture samples increases with temperature and the size of the dimple becomes deeper, exhibiting an excellent plasticity. The 6082 sheet presents anisotropy of mechanical behavior at 300 °C, this can be attributed to the fibrous grain and the Brass component {011}<211>. The anisotropic behavior seems to be slighter with an increase in temperature. No obvious anisotropic behavior was found when tensiled at 400 °C. Because it is easier to activate the slip system at elevated temperatures, meanwhile, the recrystallization begins to occur at 400 °C.