Mechanical properties and microstructure of primary and secondary AA6063 aluminum alloy after extrusion and T5 heat treatment

The mechanical properties of primary and secondary AA6063 aluminum alloy were investigated in tension on samples with different orientation (extrusion direction, ED and transverse direction, TD), after quenching in forced air and after artificial aging (T5) at 185 °C for 6 h. The microstructure of the samples was analyzed using both light optical microscopy and scanning electron microscopy on the surface of the extrudate. The strength values after artificial aging are higher than the strength after quenching in forced air due to the precipitation hardening. The tensile properties show a slight anisotropy between ED and TD. The optical microscopy investigation carried out on the extruded billet after forced air quenching shows a fully recrystallized equiaxed grains. Artificial aging improves the strength and hardness due to the precipitation of Mg2Si observed by scanning electron microscopy (SEM)