Recycled Metal Utilization on the Microstructure and Mechanical Properties of Casting Alloys

Abstract

Recycled metals have become a strategic resource for the casting industry in the transition toward sustainable manufacturing and circular material flows. This review summarizes the present understanding of using 100% recycled alloys in foundry applications, covering microstructural evolution, mechanical properties and energy efficiency. The aim is to make an integrated assessment of the scientific findings and industrial practices that underpin the wider adoption of recycled feedstock in metal casting. This review summarizes what is known about the influence of impurities, oxide formation and melt treatment on the resultant microstructure. Various observations are reported that trace impurities of alloying elements may modify the dendritic morphology, eutectic phases, and porosity of recycled metals; often these can be minimized by proper refining and filtration. The mechanical performance results vary depending on the alloy type, recycling route and melting practices; nevertheless, a considerable number of research findings prove that tensile strength, hardness and fatigue resistance of castings manufactured from 100% recycled feedstock remain comparable to those produced from primary metals when proper process control is applied. This review also points out the importance of melt cleanliness, degassing procedures and alloy chemistry stabilization in achieving consistent quality. Overall, the collected research indicates that 100% recycled metals can be effectively integrated into the casting processes and are an essential part of sustainable foundry operations. In this context, the utilization of recycled metals brings considerable benefits in terms of energy consumption reduction, minimizing carbon emissions, and supporting circular economy principles. This review is expected to help future studies and industrial practices by summarizing challenges, key technological developments, and opportunities for full-scale implementation.