Abstract: The paper presents an investigation into the heading of rivet shape head form aluminum-copper porous cylindrical composite specimen clamped at one of its ends, at different strain rates (based on ram velocity) during cold forging under lubricated end conditions. The composites of different compositions were prepared and forged into rivets at different ram velocities: 1.5, 50, 100 and 150 mm/min. The forgeability of all the porous composites into rivet shape head was observed. The yield criterion as proposed by Tabata and Masaki, composite friction law, an appropriate velocity field, a mathematical model considering ‘Upper Bound’ analysis was developed for relative average forging pressure on the platen during cold forging of the aluminum-copper porous composites into rivet at different ram velocities. Theoretical results have been presented graphically showing the variation of the relative average forging pressure versus percent reduction in height of the porous composites. The required ram travel has also been ascertained. Theoretical and experimentally obtained values of relative average forging pressure versus percent reduction in height were plotted for different composite- specimen and a good correlation was observed. Strain rate effect on forging load during circular rivet head forming process versus percentage reduction in height were presented graphically, analyzed and discussed critically.
Keywords: Al-Cu porous composite, strain rate, yield criterion, interfacial friction law, forgeability.