Achieving Superplasticity In the 7055 Aluminum Alloy

摘要

Superplasticity in a 7055 aluminum alloy subjected to intense plastic straining through equal-channel angular extrusion (ECAE) was studied in tension over a range of strain rates from 1.4×10{sup}(-5) to 5.6×10{sup}(-2)s{sup}(-1) in the temperature interval 300-450°C. The alloy had a grain size of ～1 urn. A maximum elongation-to-failure of -750% appeared at a temperature of 425°CC and an initial strain rate of 5.6×10{sup}(-4) s{sup}(-1), where the strain rate sensitivity coefficient, m, was about 0.46. The highest m value was -0.5 at a strain rate of 1.4×10{sup}(-3) s{sup}(-1) and T≥425°C. Moderate superplastic properties with a total elongation of about 435% and m of -0.4 were recorded in the temperature interval 350-400°C, where no cavitation was found.