Cold upsetting experiments were carried out on sintered Fe-0.8%C-1.0%Si-0.8%Cu steel preforms in order to evaluate stress — strain, stress — densification and work hardening characteristics.  Powder preforms of 86% theoretical density and 0.40 of initial aspect ratio were prepared using a suitable die — set assembly on a 1MN capacity hydraulic press. Sintering was carried out in an electric muffle furnace for a period of 90 minutes at 11500C.  Each sintered compact was subjected to incremental compressive loading of 0.04MN under two different lubricating constraints namely nil/no and graphite lubricant till fracture appears at free surfaces.  The behavior of applied stresses with strain and densification exhibits a continuous enhancement but with three different modes of responses.  The first and third stage offers high resistance to deformation, whereas the second stage shows virtually steady state, deformation needed gradual increase in applied stresses but with high rate of densification. The instantaneous strain hardening exponent ni and strength co-efficient Ki of the aforementioned steel preforms were calculated and found to enhance continuously with the continuous enhancement of deformation and densification.