Authors:
Petr Mamykin (1), Jean-Philippe Chateau-Cornu (1), Frederic Bernard (1)
1- Institut Marey – Maison de la Métallurgie, France
Abstract:
This study examines the possibility of simulating the rearrangement stage of 316L steel powder using a modified cam-clay model. The oedometric compression tests were carried out at up to 900°C using an SPS device. Unlike clay soils, the virgin consolidation line is non-linear, with a slope dependent on volumetric deformation. The dependency of the slope is characterized at different temperatures and a consolidation law under isostatic pressure is proposed. The initial pressure at which the virgin powder starts to densify plastically was successfully adjusted. This adjustment was made using density measurements obtained after HIP interrupted tests performed on the same powder encapsulated in a spherical container. The complete consolidation law can be implemented in FEM simulations to take into account the rearrangement stage in the densification of industrial parts.
The second part aims at determining the optimal simulation parameters for oedometric cold pressing of the powder powder using the discrete element method. The simulation uses the Hertz-Mindlin contact model and the Spherical Johnson-Kendall-Roberts model to account for powder particle adhesion. Simulation parameters have been optimised through iterative refinement. The particle size distribution is measured experimentally by sieving. For this size distribution, the values determined for the simulation parameters were 5 nanoseconds for the minimum time step, 0.002 for the friction coefficient and 0.36 for the adhesion coefficient. These parameters ensure accurate representation of the powder behaviour in monotonic compression but the simulation lacks of efficiency when unloading-reloading stages are applied.
DOI:
https://doi.org/10.59499/EP235751775