Microstructure Homogeneity in AA6063 Alloy Processed by Cyclic Expansion Extrusion

Abstract:

Aluminium (AA6063) alloy was subjected at 200oC to cyclic expansion extrusion (CEE) - a severe plastic deformation (SPD) process - up to 10 passes. The extrusion die angle is 22.5o. Microstructure examination revealed evidence for grain refinement, which had reduced from 20μm±5.8 (average) in the parent material to 4.8 μm±1.4 (average) after 10 passes (i.e. ~76% of reduction). The microhardness and tensile strength had increased, while the elongation decreased with the number of passes. The specimen after 4 passes had the highest hardness of 591 HV (about 40% improvement) and the highest tensile strength value of 153 MPa which is ~23% more than that of the parent material. The hardness and tensile strength values decrease marginally on further processing, although throughout they are higher than that of the parent material. With increasing of number of passes, grain refinement and the fraction of high-angle boundaries continued to increase, which in the end was ~ 40%.

• Periodical: Defect and Diffusion Forum (Volume 385)
• Pages: 223-227
• DOI: https://doi.org/10.4028/www.scientific.net/DDF.385.223
• Online since: July 2018
• Authors: V. Babu, S. Balasivanandha Prabu*, K. Anantha Padmanabhan
• Keywords: Cyclic Expansion Extrusion (CEE), Mechanical Properties, Severe Plastic Deformation, Ultrafine Grain (UFG)

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