Some Al-Mg-Si commercial alloys were extruded at various temperatures and rates. Mechanical properties, optical and electron microstructures, and textures of the as extruded and T6 tempered rods were investigated.
The press effect was observed in the T6 tempered rods extruded above about 450°C and the rods exhibited about 10kg/mm² higher yield and tensile strength than those of rods free from fibrous structures.
The critical extrusion conditions which produce the press effect depend on the magnitude of recrystallization retarding effect of dispersoids and can be understood qualitatively in terms of a critical stored energy.
The press effect may be resulted from two effects; the subgrain hardening effect and the <111> texture strengthening effect retained completely after solution heat treatment. The former contribution seems to be as large as that of the latter.