The Effect of Equal-Channel Angular Pressing Processing on Microstructural Evolution, Hardness Homogeneity, and Mechanical Properties of Pure Aluminum

Equal-channel angular pressing (ECAP) is among the most applicable severe plastic deformation processes used to fabricate ultrafine-grained materials with superior mechanical properties. In this work, a commercial purity aluminum has been processed via ECAP process up to four passes. The influence of ECAP routes (A and B_c) on the mechanical properties of the material and its grain size was investigated. Microstructural observations of the as-annealed and the rods processed via ECAP were undertaken using optical microscopy. Hardness profiles and contour maps of sections cut perpendicularly and parallel to the load direction were assessed to investigate the effect of ECAP processing on the hardness distribution across the deformed rods. Compressive properties of the rods were also examined. In addition, digital images correlation was used to display the stress distribution along the longitudinal section of the processed sample during the compression test. Experimental results showed that, 1-pass of ECAP results in an inhomogeneous distribution of strain hardening, which has lower values at the disc center, and increases gradually toward the center. The hardness values of the processed rod increase by 73 and 60.5% post ECAP processing at the rod periphery and center, respectively; on the other hand, ECAP processed rods via 4-A showed an increase in the yield and compressive strengths by 54 and 39%, respectively, compared to the as-annealed condition.