Study of the Behaviour of Low Alloy Steel Powder During Uniaxial Cold Compaction by Means of Single Action Tests

摘要

This work investigated the behaviour of a low alloy steel powder (diffusion bonded iron powder, graphite and lubricant mix) in uniaxial cold compaction, aiming at determining the characteristics of the powder affecting densification. Single action compaction tests were performed, both upwards and downwards, producing specimens with two different H/D ratios. The data recorded by the press (forces applied to the upper punch and the die, displacements of both upper punch and die) were used to calculate the mean axial stress applied by the upper punch to the powder column and the mean radial stress exerted by the die. The relationships between axial and radial stress, relevant both to the elastic and to the plastic deformation, allowed determining the friction coefficient between the powder column and the die wall, the radial stress transmission coefficient and the flow stress of the material as functions of the relative density.