Microstructure, mechanical properties and deformation mechanisms of an Al-Mg alloy processed by the cyclical continuous expanded extrusion and drawing approach

Abstract

Al-Mg alloys are an important class of non-heat treatable alloys in which Mg solute and grain size play essential role in their mechanical properties and plastic deformation behaviors. In this work, a cyclical continuous expanded extrusion and drawing (CCEED) process was proposed and implemented on an Al-3Mg alloy to introduce large plastic deformation. The results showed that the continuous expanded extrusion mainly improved the ductility, while the cold drawing enhanced the strength of the alloy. With the increased processing CCEED passes, the multi-pass cross shear deformation mechanism progressively improved the homogeneity of the hardness distributions and refined grain size. Continuous dynamic recrystallization played an important role in the grain refinement of the processed Al-3Mg alloy rods. Besides, the microstructural evolution was basically influenced by the special thermomechanical deformation conditions during the CCEED process.