Mechanical and microstructural characterization of commercial AA5083 aluminum alloys

The superplastic forming (SPF) process has been of interest to automotive manufacturers for several years because of two imperative goals. The first one is the simplification of the manufacturing process for sheet-body panels and the second reason is to follow government regulations to reduce vehicle mass, by using aluminum. However, the high cost associated with superplastic materials and slow production cycle times have limited the use of SPF to niche automobile manufacturing operations. To overcome these limits, research on SPF has been directed to forming at lower temperatures, at faster strain rates and with lower cost materials. AA5083 superplastic materials hold great promise for high-volume SPF production. However, several technical issues related to the material are still not well understood. The present investigation characterizes the mechanical and microstructural behavior of eight commercial 5083 materials. Conclusive evidence on the deformation mechanisms active in the range of conditions typical for SPF operations, low rates and high temperatures, but also at high-rate and low-temperature conditions, are presented. Predictive equations, useful to establish a predictive basis for SPF forming, are constructed. The issue of cavitation in superplastic materials, leading to poor post-formed properties of the material and ductility variations, is treated. A relation between cavitation, ductility and microstructural features is presented. These results should be quite useful in the development of improved commercial superplastic 5083 materials and for enhancing the capabilities of the SPF process.