Developing a superplastic forming capability in a commercial aluminum alloy without scandium or zirconium additions

Tests were undertaken to determine the feasibility of producing a superplastic forming capability in a commercial Al-2024 alloy through processing by equal-channel angular pressing (ECAP), where this alloy was selected because it contains no scandium or zirconium additions that are generally beneficial in retaining an array of small grains. Processing by ECAP produced grain sizes in the range from ∼0.3 to ∼0.5 μm and static annealing showed these ultrafine grains were reasonably stable at temperatures up to ∼700 K. Superplastic elongations were achieved after ECAP with a maximum elongation of ∼500% at 673 K when using a strain rate of 1.0×10−2 s−1. The strain rate sensitivity was measured as ∼0.3 suggesting that dislocation glide is the rate-controlling mechanism. These results demonstrate the potential for achieving high tensile ductilities in conventional commercial aluminum alloys through processing by ECAP.