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

A new mathematical equation taking into account of all new and relevant parameters to represent the flow behaviour of partially dense P/M materials during the case of simple upsetting-compression test is proposed in this paper. The ratio of the yield stress of the P/M-porous material to the yield stress of 100% dense material is found to be increasing with increase in deformation strain. Further, a theory for simple plastic instability and work hardening rate of porous P/M-material has been developed with strain hardening index and strain rate sensitivity parameters.