Flow stress and hot deformation activation energy of 6082 aluminium alloy influenced by initial structural state

Abstract

Stress-strain curves of the EN AW 6082 aluminium alloy with 1.2 Si-0.51 Mg-0.75 Mn (wt.%) were determined by the uniaxial compression tests at temperatures of 450-550 degrees C with a strain rate of 0.5-10 s(-1). The initial structure state corresponded to three processing types: as-cast structure non-homogenized or homogenized at 500 degrees C, and the structure after homogenization and hot extrusion. Significantly higher flow stress appeared as a result of low temperature forming of the non-homogenized material. Hot deformation activation energy Q-values varied between 99 and 122 kJ.mol(-1) for both homogenized materials and from 200 to 216 kJ.mol(-1) for the as-cast state, while the Q-values calculated from the measured steady-state stress were always higher than those calculated from the peak stress values. For the extruded state of the 6082 alloy, the physically-based model was developed to reliably predict the flow stress influenced by dynamic softening, temperature, strain rate, and true strain up to 0.6.