Mechanical Reliability of Scrap-Derived Al7075-Type Alloys

Abstract

Recycling of high-strength aluminum alloys has gained increasing importance due to sustainability and resource efficiency requirements. During recycling, the presence of melt-related defects may significantly affect the final product quality. In this study, the mechanical reliability of scrap-derived Al7075-type alloys was systematically investigated by correlating defect populations with mechanical performance. Scrap-derived alloys produced from Al6063 and Zamak-5 feedstocks were compared with a primary-cast alloy and a commercial wrought Al7075-T651 reference material. Mechanical behavior was evaluated using hardness, tensile strength, elongation, and impact toughness measurements through Weibull statistical analysis tools. The results reveal that mechanical reliability is strongly influenced by defect populations introduced during melt processing. While hardness showed limited sensitivity to defects, tensile strength, elongation, and impact toughness exhibited significant statistical scatter depending on melt quality. Alloys associated with lower bifilm index values generally demonstrated higher B10 reliability and larger Weibull modulus values. Fractographic observations confirmed the presence of oxide-film and bifilm-related fracture features. The findings demonstrate that recycled feedstocks can be used to produce reliable Al7075-type alloys when melt cleanliness and defect populations are properly controlled.