The effect of temperature on the formability of a high strength aluminium automotive alloy

The desire to reduce weight in automotive products is driven by a need to reduce CO2 emissions. As such, to allow further weight reduction, higher performance aluminium alloys are in demand for sheet metal body structures. Due to their high strength to weight ratio 7xxx alloys are seen as an ideal candidate for this, however their use to date has been limited by poor formability. The formability of a 7xxx candidate alloy, 7021, has been assessed by way of tensile testing and deep drawing experimentation, both at room temperature and over an elevated temperature range. The formability of the alloy improved as the temperature was increased due to the lower flow stress experienced by the material during drawing. Microstructural analysis of samples post-forming showed a dimpled fracture surface with the dimple size increasing with temperature. Voids close to the fracture surface were shown to initiate at Fe-containing particles. Copyright ?? 2013 MS&T'13??.