An analysis of thermo-mechanical treatments of a 2618 aluminium alloy: study of optimum conditions for warm forging

The warm formability of a solution-treated 2618 aluminium alloy was investigated by means of torsion tests at temperatures between 423 and 573 K. Dynamic precipitation took place during deformation raising the flow stress and lowering ductility. The flow stresses were substantially higher than those observed by testing the same alloy in the as-extruded state. At the lowest temperatures dynamic precipitation resulted in a continuous increase of flow stress, while above 500 K dynamic precipitation and subsequent coarsening of precipitates resulted in a peak of equivalent-stress versus equivalent-strain curves, followed by softening. These differences in deformational behaviour were attributed to the nature of precipitates, as well as to different kinetics of the ageing processes at each testing temperature.