Effect of high iron content on direct recycling of unhomogenized aluminum 6063 scrap by Shear Assisted Processing and Extrusion

Abstract

Iron contamination in secondary aluminum scrap must be diluted with primary aluminum during conventional recycling to bring subsequent alloys within allowable Fe limits. In this study, Shear Assisted Processing and Extrusion (ShAPE) was investigated as a methodology for tolerating high Fe content during extrusion of secondary aluminum scrap. ShAPE was used to fabricate aluminum alloy 6063 tubing from secondary industrial scrap billets in the as-cast, unhomogenized condition. Iron content up to 0.3 wt% was investigated to explore the tolerance of ShAPE to ferrous contamination in the feedstock. Extensive refinement of Fe-rich second phases enabled tensile properties to meet, and in some cases exceed, industry standard values. For process temperatures of 470–530 °C, using unhomogenized billets with 0.3 wt% Fe and T6 properties yielded an average of 214 MPa yield strength, 243 MPa ultimate strength, and 15.5 % uniform elongation. For 0.2 wt% Fe and T6 condition, properties averaged 233 MPa yield strength, 260 MPa ultimate strength, and 16.5 % uniform elongation. These results suggest that ShAPE is a potential manufacturing route that can avoid the need for adding primary aluminum to dilute Fe during recycling.