Mechanisms of Heat Treatment Influencing Tensile Strength and Hardness of Recycled Aluminum Alloys in Brazil

Abstract

Brazilian recycled aluminum alloys are increasingly used in automotive, construction, and lightweight structural applications due to their favorable strength-to-weight ratio, corrosion resistance, and sustainability advantages. The heterogeneous composition of scrap materials, including automotive, industrial, and consumer sources, introduces challenges in achieving consistent mechanical performance. This paper reviews the mechanisms by which heat treatment affects tensile strength and hardness, emphasizing solution treatment, artificial and natural aging, precipitation hardening, solid solution strengthening, grain refinement, and residual stress interactions. Industrial case studies in Brazil illustrate how tailored heat treatment protocols mitigate material variability, optimize mechanical properties, and support sustainable production practices. Theoretical insights and mechanistic models are discussed to guide future research and industrial implementation, providing a framework for improving performance predictability in heterogeneous recycled aluminum batches.