Optimizing homogenization parameters for better stretch formability in an Al–Mn–Mg alloy sheet

The present study examines the effect of homogenization of roll-cast material on the formability and microstructure of Al–Mn–Mg alloy sheets under uniaxial and biaxial deformation modes. The effect of various process variables investigated and an optimized homogenization cycle for improving the stretch formability are presented. The stretch formability of sheets have been characterized in terms of limit strains in forming limit diagrams (FLDs). The phenomenon of recrystallization and the effect of second phase particles have been investigated in cold rolled sheets and the limiting grain sizes at different annealing temperature calculated on the basis of the Zener limit equation. It appears that surface roughening which is in turn a result of grain coarsening is an important formability parameter in the homogenized materials annealed at high temperatures.