Formability of Aluminum Alloy Sheets

High strength-to-weight ratio materials are becoming of increasing importance in the automotive industry. Some aluminum alloy sheets offer strength equivalent to low-carbon sheet steel at one third of the weight. However, for these alloys no production stamping experience exists and little meaningful laboratory data have been accumulated. This study was conducted to provide such laboratory information. Complete tensile properties and forming limit curves (FLC), as measured by a laboratory technique developed by the author, were determined for the aluminum alloys with a wide range of properties and were compared to the properties of low-carbon steel. All the aluminum alloys were found to have lower FLC’s, lower r values and equal or lower strain hardening capacities than sheet steel. Therefore their formabilities will be less than those of steel for all modes of sheet forming. This predicted press performance was verified for some of these alloys in limited press trials on a deck lid (inner panel) stamping.