Search

The plastic deformation behavior of forward extrusion, equal channel angular pressing, and a combination of the forward extrusion and equal channel angular pressing processes are analyzed by the finite element method. Simulations were carried out under realistic conditions by considering the strain hardening of the material and the degree of friction. Strain homogeneity in the combined processes is also compared to that of the individual forward extrusion and equal channel angular pressing processes. The plastic flow is more complicated and the strain induced is non-uniform in the combined processes. However, the combined processes show no corner gap formation. Moreover, it led to the development of higher strains in a single step compared to the individual processes. In addition, the load requirements for the combined processes are higher than the summation of loads of the individual processes. © 2010 The Japan Institute of Metals.

In current studies, equal channel angular pressing process (ECAP) and modified ECAP processes are simulated under ideal conditions to compare the deformation characteristics. The deformation behaviour is more complicated and the strain induced during the processes is highly non-uniform in the modified ECAP processes except in the equal channel multi-angular pressing (ECMAP) process with Route C. The strain homogeneity is more of a possibility with ECAP and ECMAP with Route C processes. The deformation stress state is widely distributed in nature in modified ECAP processes than in conventional ECAP. In addition, the load requirements are also higher in modified ECAP processes with that of the ECAP process.

Equal channel angular pressing (ECAP) is so far the most viable severe plastic deformation procedure to extrude material by using specially designed channel dies without any substantial changes in geometry and to prepare an ultrafine grained material. Magnesium is the lightest of all structural metallic materials, but a typical hard-to-deform metallic material due to its HCP structure and associated slip systems. ECAP has been applied for a processing method of severe plastic deformation to achieve grain refinement of magnesium and to enhance it's low ductility. In particular, we investigated the deformation and fracture behavior of pure magnesium workpiece using experimental and numerical methods. The finite element method with different ductile fracture models was employed to simulate plastic deformation and fracture behavior of the workpiece.

In order to obtain high-quality products in powder metallurgy, it is important to control and understand the densification behavior of metallic powders. The effect of the powder characteristics of magnesium powders on the compaction behavior was investigated in this study by experimental and theoretical methods. A modified version of Lee-Kim’s plastic yield criterion, known as the critical relative density model, was applied to simulate the densification behavior of magnesium powders, and a new approach that extracts both the powder and the matrix characteristics was developed. The model was implemented via the finite element method, and powder compaction under upsetting conditions was simulated. The calculated and experimental results are in good agreement. [doi:10.2320/matertrans.MC200724]