A finite element analysis of the superplastic forming of an aluminum alloy processed by ECAP

Finite element analysis (FEA) was used to simulate a superplastic forming operation for an aluminum alloy processed by equal-channel angular pressing (ECAP). An earlier report described the processing of an Al-3% Mg-0.2% Sc alloy by ECAP and the subsequent gas-forming of the as-pressed alloy into domes at 673 K using an unconstrained bulge test. The experiments provided detailed information on the uniaxial tensile behavior over a range of strain rates at 673 K and these stress-strain curves are now used to develop a constitutive relationship based on a strain hardening form of the power-law creep model. The FEA was performed by representing the aluminum disk as linear reduced integration continuum elements and incorporating adaptive remeshing. It is shown that, by assuming a reasonable value of 0.5 for the coefficient of friction between the disk and the clamps, the predicted superplastic forming of the disks is in good agreement with the experimental data for forming times of 30 and 60 s.