Effect of ECAP process on structure and hardness of AlMg3 aluminium alloy

Abstract

Purpose: In the present study, the effect of ECAP die and number of ECAP pressings on the structure evolution and hardness of AlMg3 aluminium alloy was investigated. Design/methodology/approach: Commercial AlMg3 aluminium alloy in the as-cast condition was processed by Equal Channel Angular Pressing method through route A using two different ECAP dies – conventional and modified with additional twist angle. Samples were processed at ambient temperature up to four passes. The investigation was carried out at ambient temperature. Two different ECAP dies were used to investigate the effect of design modification on the possibility of grain refinement to sub-micrometer size. Findings: The experimental results showed that the modification of ECAP die provides to additional grain refinement and introduces a greater amount of plastic strain into the material which results in greater increase in the properties of the investigated material. Research limitations/implications: The presented investigation results were carried out on samples, not on final products. Practical implications: Current research is moving towards to develop high strength materials with increased mechanical properties and refined microstructure that are known as ultra-fine-grained materials, compared to well-known with coarse-grained microstructure. Originality/value: The paper focuses on the investigation of microstructure evolution using mainly polarised light microscopy that reveals shear, micro-shear and slip bands that refine the microstructure of aluminium alloys. In addition, to evaluate the grain size of as ECAPed specimen, EBSD investigation was carried out.