Etude du comportement microstructural d'une poudre de fer au cours du pressage (French text)

The forming process of powder pressing in rigid dies leads to the manufacturing of porous green parts. The factors which are involved in the pressing process may be divided in three different categories: (a) factors characterizing the material: hardness, plasticity, etc., (b) factors characterizing the powder: shape, size, porosity, granular homogeneity of particles etc., (c) experimental variables characterizing the forming process: pressure, lubrication, pressing time, pressing temperature, compact shape and size, etc.; The aim of the present study was to analyze the influence of certain variables like the previous b and c categories on the densification process by using iron powder. The density variation within the green compact volume was evaluated from the particle deformation. This could be measured microscopically by defining a shape factor, which describes the modification of particle size within precisely located zones of the compact. These zones have been chosen to highlight the variation of particles' deformation on the middle section of the green compact.; The final goal of the study was to obtain a relation between the mean values of the shape factors measured on different regions of the median section of a green compact and the average density determined experimentally. (Abstract shortened by UMI.)...