Production of seamless tube from aluminum machining chips via double-step friction stir consolidation

At this present work, the feasibility of producing seamless tubes through recycling of aluminum machining chips via the double-step friction stir consolidation (FSC) process was investigated. This process was done in two distinct steps. At the first step, the chips are loaded into the container and slightly compacted, and then a rotating tool with a designated diameter is plunged into the chips at a chosen rotational speed and feed rate. Due to the frictional heating, the softened materials are compressed and merged to form a consolidated cylindrical bulk material eventually. In the second step, a rotating tool that is smaller in diameter than the first tool is again plunged into the recycled round bars at a selected rotational speed and feed rate, forcing the material radially outwards and afterwards forming tubes. The results show that the process is a feasible solution for producing structurally sound, void-free tubes directly from machining chips at two simple steps. A numerical model was implemented to predict the evolution of the main field variables including temperature, density, and strain in the process.