A preliminary study on the feasibility of friction stir back extrusion

The feasibility of producing fine-grained tubes via the novel concept of friction stir back extrusion was investigated. A rotating tool is plunged into aluminium round bar specimens at a selected feed rate, forcing the processed material radially outwards and thus forming tubes. Preliminary results show that the process is capable of producing structurally-sound, void-free tubes; optical microscopy clearly shows the presence of a stir zone, and grain size measurements indicate significant refinement in the microstructure of the starting material.

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