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The stage 1 compaction behaviour of tool steel powder under die pressing was studied. The effects of friction between the powder and the die wall were also investigated under different die pressing modes. The e1astop1asticconstitutive equations based on the yield functions by Fleck et al. and by Shima and Oyane were implemented in a finite element programme to simulate die compaction processes. Finite element calculations were compared with experimental data for densification and density distributions of tool steel powder under single and double action die pressing. Finite element calculations using the yield function by Fleck et al. agreed better with experimental data than those by Shima and Oyane. PM/0775

The thermoviscoplastic response and the densification behaviour of porous alloy steel preforms under hot upsetting conditions are investigated at various temperatures and strain rates. A higher den...

A mathematical model is proposed to describe the variation with time of pressure, relative density, and temperature for metal powders during hot compaction. The model includes instantaneous response, equilibrium response, and creep response and is based on a micromechanical (hollow sphere) analysis. However, the development is mostly empirical, based on experimental data from hot compaction of iron powder. The instantaneous and equilibrium responses are described by linear response laws, whereas time dependent densification is described by a power law creep response. The experimental data support these assumptions. Agreement between theoretical curves and experimental data is very good. PM/0500

The densification behaviour of iron and copper powders during die compaction has been simulated with several plastic models and the results compared with actual experimental data. The experimental data of Brown were used to obtain the empirical constants of the Cam–clay model. The Cam–clay model simulates actual behaviour during die compaction significantly better than do the Shima and Fleck models. PM/0750