Superplastic tensile ductility was attained when specially-processed AA5083 materials were strained in tension at relatively high strain rates, in the range of the transition from grain-boundary sliding to solute drag creep control of deformation. Quick plastic forming technology involved deformation at such strain rates, and the relative contributions of grain-boundary sliding and solute drag creep to the strain during deformation in this strain rate regime were examined in this investigation. The additive, independent contributions of grain-boundary sliding and solute drag creep to the elevated temperature deformation of fine-grained materials were reviewed. The transition from grain-boundary sliding to solute drag creep in grain-refined AA5083 materials was evaluated by several methods, including the assessment of initial transients during straining and of transients during strain-rate change tests; the strain-rate dependence of the flow stress; the dependence of ductility upon strain rate; flow localization behavior and fracture mode; cavitation growth; the evolution of microstructure and microtexture during deformation; and comparison with phenomenological models for the grain-boundary sliding to solute drag creep transition.

Characteristics of the Transition from Grain-Boundary Sliding to Solute Drag Creep in Superplastic AA5083. T.R.McNelley, K.Oh-Ishi, A.P.Zhilyaev, S.Swaminathan, P.E.Krajewski, E.M.Taleff: Metallurgical and Materials Transactions A, 2008, 39[1], 50-64