Microstructural Evolution and Plastic Flow Behavior of As-Equal Channel Angular Pressed 5083 Al Alloy in Low temperature superplastic Regime

Abstract

In this study, the plastic flow behavior of ultrafine grained 5083 Al alloy fabricated by severe plastic deformation was examined in conjunction with microstructural evolution during deformation in the low temperature super-plasticity regime. The present investigation was aimed at providing a better understanding of the nature of the low temperature superplasticity of ultrafine grained metallic materials. For this purpose, an ultrafine grained structure was introduced into the commercial 5083 Al alloy by equal channel angular pressing. A series of tensile tests was performed on the as-equal channel angular pressed samples at the initial strain rates of 10-5 ~10-2 sec-1 and temperatures of 498~548 K, belonging to the low temperature superplasticity regime. The relationship between the true stress and true strain rate showed a sigmoidal behavior in a double logarithmic plot. The superplastic elongation was obtained within the limited intermediate strain range of 10-4 ~10-3 sec-1 at 523 and 548 K. The microstructural examination and analysis of plastic flow curves revealed that low temperature superplasticity of the present alloy was attributed to dynamic recrystallization. In addition, necking instability during low temperature superplastic deformation of the alloy was discussed by applying Harts necking instability criterion.