Effect of superplastic deformation on the grain size and tensile properties of Al-6.2Zn-2.5Mg-1.7Cu (7010) alloy sheet

Abstract

An Al-Zn-Mg alloy (7010) was cold-rolled and annealed to produce a small recrystallized grain size, and superplastically deformed in the temperature range 475 to 520° C at strain rates $$\dot \varepsilon = {\text{1}}{\text{.1 x 10}}^{{\text{ - 5}}} $$ to 2.8×10−3 sec−1. At 500° C and $$\dot \varepsilon = {\text{2}}{\text{.8 x 10}}^{{\text{ - 5}}} $$ sec−1 superplastic elongations up to 350% were obtained, but above about 60% elongation the residual room-temperature tensile properties after heat treatment decreased due to increasing grain-boundary cavitation. Grain growth rates were increased by superplastic strain.