Phenomenon of instantaneous strain hardening behaviour of sintered Al–Fe composite preforms during cold axial forming

Cold upsetting experiments were carried out on sintered Al–Fe composite preforms in order to evaluate their work-hardening characteristics. Preforms of 92% of theoretical density, with two initial aspect ratios were prepared using a suitable die-set assembly on a 0.6 MN capacity hydraulic press. Sintering was carried out in an electric muffle furnace for a period of 1 h at 520 °C. Each sintered compact was subjected to incremental compressive loading after each step of deformation. The instantaneous strain-hardening exponent instantaneous strain-hardening exponent (ni) and strength coefficient instantaneous strength coefficient (ki) of the Al–Fe composite preforms were calculated and found to be reached the peak value when the deformation or packing density is at low value. Further, it has been observed that the value of ni and ki decreased and found to be constant It has further been established that the iron particle-size of the preforms played a predominant role in influencing both ni and ki.