A mathematical theory of plasticity for compressible powder metallurgy materials - Part III

A new mathematical equation taking into account of all new and relevant par ameters to represent the flow behaviour of partially dense PI M materials d uring the case of simple upsetting-compression test is proposed in this pap er. The ratio of the yield stress of the PIM-porous material to the yield s tress of 100% dense material is found to be increasing with increase in def ormation strain. Further, a theory for simple plastic instability and work hardening rate of porous P/M-material has been developed with strain harden ing index and strain rate sensitivity parameters. (C) 2000 Elsevier Science S.A. All rights reserved.