Abstract
The radial stress in the cylindrical compact of iron and copper powders of different characteristics during compaction has been evaluated by the indirect method, measuring the elastic strain of the steel die, and the following results have been obtained.
1) In pressing process the slope of the curve for the relation between the average axial and the average radial stress increases with increasing the average axial stress and gradually approaches to the unity.
2) By lubricating the powders with 0.5 wt% of zinc stearate, the sliding motion of the particles in the powder mass is kept up to the higher densification stage and the average radial stress is considerably reduced.
3) In unloading process after compaction, the reduction rate of the average radial stress is larger than that of the average axial stress at the outset of unloading and the curve for the relation between the average axial and the average radial stress does not coincide with that for pressing process.
4) The value of residual radial stress after complete unloading is varied with the class of powder but independent of the lubrication.
