Improvement of mechanical properties for EN AW 6082 aluminium alloy using equal-channel angular pressing (ECAP) and post-ECAP aging
Keywords:EN AW 6082 aluminium alloy, ECAP, strength, tensile ductility, notch toughness heterogeneous microstructure, strain hardening
AbstractThe mechanical properties and microstructure ofEN AW 6082 aluminium alloy subjected to severe plastic deformation and aging treatment were compared with those of the extruded and artificially aged state (initial state). The initial state of alloy subjected to solution annealing and quenching was severely deformed at ambient temperature by equal channel angular pressing (ECAP) following route C up to three passes. Polyedric microstructure of initial state was considerably changed by the repetitive ECA-pressing. Deformation bands with different density of slip lines were observed in microstructure of ECAPed and aged states, which indicated non-uniform deformation across the cross-section of ECAPed specimens. The high strength of ECAPed states was the result of the strain hardening of alloy. Application of the artificial aging treatment after the severe plastic deformation of analyzed alloy in the ECAP die improves the ductility and the strength of EN AW 6082 aluminium alloy. This was due to that the hardening effect by expected sequence Mg2Si precipitation dominates the softening effect by microstructure with low recovery and relaxation of internal stress during aging treatment. The reason of low notch toughness of ECAPed and aged alloy is due to the intensive and heterogeneous strain hardening of alloy during ECA-pressing. A moderate improvement of notch toughness was induced by application of the artificial aging treatment for ECAPed alloy state instead of the natural aging.
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