Comparative Characterisation of Aluminium Bars Produced from Discarded Aluminium Parts

Abstract

This research explores the mechanical and microstructural properties of aluminium bars made from discarded automotive, construction, and household materials. Samples: Ford gearbox casing (AGBC), Maltina cans (AMC), Tower long-span roofing sheets (ARS) and 33 kV overhead line cables (AHVC) were remelted and recast using the sand moulding method. The tests of hardness and impact were performed depending on ASTM E10 and ASTM E23, respectively. There was a significant difference in mechanical behaviour: AGBC had the highest Brinell hardness (382.39 +/- 3.12 BHN) and lowest impact energy (20.40 +/- 0.61 J), and AHVC had the best toughness (65.01 +/- 0.52 J) and moderate hardness (137.79 +/- 2.11 BHN). Analysis of the SEM indicated that porosity and Si- and Fe-rich intermetallics were the causes of the strength-ductility trade-offs in the samples. It is concluded that in recycled aluminium, alloy composition and solidification control are the determining factors in performance. These results offer a strategic framework in the selection and improvement of aluminium scrap towards specific industrial applications, including automotive, building construction, lightweight structural parts, etc.