Comparison in Deformation and Fracture Behavior of Magnesium during Equal Channel Angular Pressing by Experimental and Numerical Methods

Abstract

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.

The evolution of damage in perfect-plastic and strain hardening materials processed by equal-channel angular pressing

“…It is apparent from the simulation that there is a severe localization of flow around the internal cracks and this leads to crack propagation and billet segmentation. Furthermore, the curved surfaces at the tops of the individual segments are fully consistent with reports of billet failure by segmentation in magnesium [33,49] and titanium [23]. By contrast, Fig.…”

“…There have been some limited attempts to make use of FEM in evaluating the development of damage in ECAP [32,33]. However, any comprehensive analysis must incorporate the mechanical characteristics of the material by using the flow curve to provide information on the variation of stress with the imposed strain and by evaluation of the maximum damage for fracture.…”

“…(2), fracture occurs when C N reaches a critical value which depends upon the material and its processing history. To date, this criterion has been widely used to predict the occurrence of fracture in different metal-working processes including in some analyses of ECAP [14,16,[31][32][33].…”