An Effective and Economical Method to Improve Structural Homogeneity and Mechanical Properties of Al–Mg Alloy Processed by ECAE

Abstract

The formation of the dead metal zone (DMZ) in equal channel angular extrusion (ECAE) process significantly affects the deformation uniformity and mechanical properties of work material. The aim of the present study is to investigate the effect of the dead metal zone on structural homogeneity and hardness of Al 5083 alloy processed by ECAE and suggest the way to minimize that adverse effect. In this work, the rectangular billets with 1-mm-thick copper casing on two longitudinal faces and square billets with no casing are processed by ECAE up to four passes in route A. It was observed that the soft and ductile nature of the copper casing allows smooth flow of the work material at low pressing loads as compared to the alloy ECAE’d without a casing. Field emission scanning electron microscope (FESEM) images of the processed material with casing show the noteworthy improvement in structural homogeneity and grain refinement than another set of billets. The obtained structural homogeneity indicates the uniform strain distribution in the processed material is achieved by minimizing the formation of the dead metal zone at the intersection of ECAE die channels. The higher hardness and tensile strength measurements of the processed materials indicate the significance of grain refinement and uniform strain distribution. The variations in the test results confirm the non-homogeneous strain distribution caused by the dead metal zone is high for the billets processed with no copper casing.