Simulation of Powder Compaction using Equal Channel Angular Extrusion at Room Temperature: Comparison of Two Constitutive Theories
The process of powder compaction through Equal Channel Angular Extrusion (ECAE) at room temperature was modeled using the finite element analysis package ABAQUS. Two powder compaction models, the Gurson model and the Duva and Crow model, were used to test their efficacy in modeling this process. Modeling parameters like friction coefficients, interaction conditions were determined by comparing the simulations for solid billet and an empty can with actual experimental runs for loads, shear angle and workpiece geometry. The simulations using the two models showed no significant difference in the stress in the powder during the extrusion. 2-D simulations were used to show the efficacy of two passes of ECAE in achieving full densification in the extruded workpiece. The results obtained from the simulations were also compared to experiments conducted to compact copper powder with a size distribution of 10
μm to 45μm. It was found through experiments that the powder does not fully consolidate near the outer corner of the workpiece after the first ECAE pass and the results from the simulations were used to rationalize this phenomenon. Modifications made to the process by applying a back pressure during the simulations resulted in a uniformly compacted powder region. It was also found that the loads required to consolidate a powder through ECAE are much lower than conventional pressing or compression to achieve the same amount of compaction.