Abstract
Repetitive Upsetting - Extrusion (RUE) process which was originally invented for bulk mechanical alloying is currently being used to process bulk materials. Bulk materials are subjected to severe plastic deformation (SPD) using the same die design that was used to process powder materials. A more recent study on the RUE process has revealed that the current die design is not appropriate for processing bulk materials as it imparts defects such as axial hole or funnel during extrusion and folds or laps during the upsetting stage of successive RUE cycles. A modified RUE die design is proposed in this work to avoid these defects. Deformation behaviour of a bulk commercial pure copper during RUE using the modified die design has been evaluated using finite element analysis (FEA). Actual RUE experiments on commercial pure copper have also been carried out to validate the FEA results. Results obtained indicate that the modified die design can be successfully used to subject bulk materials to large number of RUE cycles.

Key words
upsetting, extrusion, RUE, SPD, copper

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