The present paper aims at studying the net-shape closed-die sinter-forging of centrally located cylindrical preforms within closed dies. The net-shape sinter-forging has been considered in two stages; where first stage consists of preform free barreling and the second stage consists of constraint deformation during which die corners are continuously formed and filled till the process is completed. The experiments were carried on a hydraulic press using closed-die set having upper and lower punches with centrally located cylindrical recess cavities having diameter equal to that of the cylindrical preforms, so that preforms can be loaded centrally with respect to the axis of the central container. Three separate modes of deformation were considered during the theoretical analysis using 'Upper Bound' approach, which were based on the different division of preform. The generalized expressions for the velocity field, strain rates, internal, frictional, inertia, energy dissipations and average forging loads have been formulated for each of these cases. The effect of die velocity, preform aspect ratio on energy dissipations, die cavity fills and die loads were investigated and results were verified experimentally and compared. It is expected that the present work will be useful for the analysis of net-shape forging of sintered materials.
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