Outlining the Limits of Friction Stir Consolidation as Used as an Aluminum Alloys Recycling Approach

Friction stir consolidation (FSC) is a solid-state process that recycles metal scraps economically and eco-friendly compared to the conventional melting method. The process parameters especially processing time and rotational speed, have a crucial role in achieving a sound disc during FSC. The current study answers the research question of how far these process parameters can be effective when the mass of chips to be recycled increases. In specific, an experimental setup was analyzed that was previously identified as challenging for recycling 20 g chips of aluminum alloy AA 2024-O. Rotational speed was set doubled, and processing time was increased up to 1.5 times of their initial values. The results were found opposing to the reported one. It was noticed that raising the processing time and rotational speed are not always promising to achieve a quality consolidated disc with better mechanical properties. In contrast, they can lead to unconsolidated discs with more non-homogeneous mechanical properties. Thus, this research work highlights the hidden challenges in producing a sound disc during friction stir consolidation.