Densification of iron compacts with various initial porosities under hydrostatic pressure

Abstract

This study evaluated the effects of hydrostatic pressures up to 1104 MPa on densification of porous iron containing 0.3–11.1% porosity. For the porosities studied, densification as a result of pressurization increased with hydrostatic pressure and initial porosity. The 0.3% porosity iron was the only one whose density did not increase with pressurization up to 1104MPa. Current deformation models of ductile porous materials based on Gurson's yield criterion and rigid-plastic FEM analysis predicted much faster densification with pressurization than observed for porosity contents of 6.2% or less. A reason proposed for this behavior is the omission in the models of an internal pressure which builds up in the pores during the compaction process. A modification is introduced to Gurson's model to take account of internal pressure effects. The modified model exhibited excellent agreement with the experimental observations and provides a constitutive relation for the simulation of compaction and forming processes of P/M parts.