Densification of sintered porous metal under hydrostatic pressure

Understanding of the deformation behavior of porous metals during forming is very important in achieving good quality powder metallurgy parts. The elastic-plastic response of porous metals is influenced by the internal pores. Yield criteria for porous metals should take the pore effect into account. Deformation behavior of porous metals has been analyzed by many investigators using slip-line field theory, limit analysis, and finite element analysis. Recently Lee and Kim reviewed yield criteria for porous metals and modified a yield equation suggested by Doraivelu et al. so that it could incorporate one parameter which could be estimated from the yield stress vs. initial relative density data. Biner et al. have reported densification results for porous iron specimens with various initial porosities when they were subjected to hydrostatic pressure. In order to explain their measured results, they modified Gurson's yield equation to fit their experimental value. The purpose of this work is to examine how the yield equation predicts the data by Biner et al.