An analytic study of porosity evolution in powder metallurgy forming process

The behavior of a porous metal in a closed-die compression test is studied with the aid of a Gurson-type model, and the results are compared with the results obtained from its quadratic approximation and the yield functions of S. Shima and M. Oyane (1976) and S.M. Doraivelu et al. (1984). Once the initial porosity and the effective stress-strain relation for the matrix is provided, the response of the powder compact can be predicted for a closed-die compaction case. The simulation demonstrates that quadratic approximation gives a response very close to that predicted by the yield functions. The Gurson-type model seems to be inaccurate at high initial porosities. However, more mechanical tests need to be performed on these yield functions before any conclusions can be made.