Some studies on the warm solid- and hollow-extrusion of sintered powder metallurgical copper preforms

The warm extrusion of sintered P/M preforms of electrolytically pure copper has been investigated for extrusion strains of 0.35, 0.5, 0.66 and 0.81 for the solid configuration and 0.43, 0.62, 0.85 and 1.09 for the tubular configuration at temperatures of 303, 363, 433, 493 and 563 K with densities of 7.45 and 7.90 g cm^?3 for the solid configuration and 7.0 and 7.7 g cm^?3 for the tubular configuration. Force requirements and microstructural property evaluation have been attempted. Using the standard axial ring-compression test on the initial preforms, the plastic properties were evaluated to enable the computation of theoretical forces. The actual forces were compared with these theoretical forces and a correction factor, φ, then determined. The influence of strain, temperature and the geometry in ensuring near to theoretical density of the extrudates has been assessed.