  Warm forming processes have been successfully applied at laboratory level to
overcome some important drawbacks of the Al-Mg alloys, such as poor formability
and large springback. However, the numerical simulation of these processes
requires the adoption of coupled thermo-mechanical finite element analysis,
using temperature-dependent material models. The numerical description of the
thermo-mechanical behaviour can require a large set of experimental tests.
These experimental tests should be performed under conditions identical to the
ones observed in the forming process. In this study, the warm deep drawing of a
cylindrical cup is analysed, including the split-ring test to assess the
temperature effect on the springback. Based on the analysis of the forming
process conditions, the thermo-mechanical behaviour of the AA5086 aluminium
alloy is described by a rate-independent thermo-elasto-plastic material model.
The hardening law adopted is temperature-dependent while the yield function is
temperature-independent. Nevertheless, the yield criterion parameters are
selected based on the temperature of the heated tools. In fact, the model
assumes that the temperature of the tools is uniform and constant, adopting a
variable interfacial heat transfer coefficient. The accuracy of the proposed
finite element model is assessed by comparing numerical and experimental
results. The predicted punch force, thickness distribution and earing profile
are in very good agreement with the experimental measurements, when the
anisotropic behaviour of the blank is accurately described. However, this does
not guarantee a correct springback prediction, which is strongly influenced by
the elastic properties, namely the Young's modulus.
