Grain size and temperature significantly influence flow behaviour in metal-forming processes. This influence is even more pronounced in micro metal forming, because so-called ‘size effects’ cause inhomogeneity within the material and inaccuracy in the shape of the items produced. In this study, a specialized metal forming system was developed to investigate the effects of grain size and temperature on the micro upsetting of copper. To refine the grains of copper, the study used equal channel angular extrusion (ECAE) and annealing techniques, after which the treated copper was carefully machined to prepare billets. The results clearly indicate how the flow stress of fine-grained copper exhibited a greater degree of sensitivity to forming temperature than coarse-grained copper. With the refinement to the grain size and increased forming temperature, it was possible to reduce inhomogeneous flow, leading to improvements in the edge quality of the deformed workpieces in micro upsetting.
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