Recycling of Magnesium Machining Chips via Shear Consolidation Processing

In this research, the feasibility of solid-state recycling of pure magnesium (Mg) chips is investigated by applying a synthesis technique called shear consolidation processing (SCP). During the SCP, machining chips are first loaded into the container and slightly compacted, and then a rotating tool with a designated diameter is plunged into the Mg chips at a selected spindle rotation speed and feed rate. Due to the huge amount of heat generation, the softened materials are compressed and synthesized to form a consolidated part eventually. The results show that the SCP process is a feasible solution for producing a void-free consolidated material directly from Mg chips in a single step. The microstructure analysis using optical microscopy (OM) and scanning electron microscopy (SEM) shows a significant grain refinement in the produced part compared with the base material (from around 900 µm to 11 µm). The recycled specimen has a much higher hardness (at least 100% increase) than the parent material and also exhibits better wear resistance. This improvement is attributed to the resulting fine-grained microstructure due to severe plastic deformation during the SCP process.