Effects of the Temperature of Warm Rolling on the Superplastic Behaviour of AA5083 Aluminium Base Alloy

Abstract

The effects of the temperature of preliminary thermomechanical treatment (TMT) on the superplastic forming parameters of commercial grade aluminium base alloy AA5083 have been studied. The TMT performed included multiple-pass warm rolling followed by cold rolling with a reduction ratio per pass approximately equal to two. The temperature of the warm rolling, T WR , was varied between 250 and 500 °C. The dependence of superplastic elongation on the temperature of warm rolling during TMT was investigated by tensile testing dog-bone samples at 350 and 500 °C. The research shows that material warm rolled at temperatures close to 350 °C yields maximum values of elongation to fracture. Refinement and change of distribution of intermetallic particles occur in the process of warm rolling AA5083. Pycnometric measurements show that the porosity of the material after a full cycle of TMT, encompassing warm and cold rolling, increases monotonically with the rolling temperature. SEM/EDS observations additionally show that warm rolling at lower temperatures is accompanied by the formation of Si- and Mg-rich segregations at the interfaces between the intermetallic particles and matrix. Both these phenomena lead to a significant decrease in the SPF properties of AA5083.