Equal Channel Angular Pressing of Canned 2124-Al Compacts: Processing, Experiments, and Modeling

Abstract

A detailed experimental and computational investigation of the influence of equal channel angular pressing (ECAP) on the microstructure and properties of precompacted 2124-Al nanostructured powder, canned in copper, was conducted. Measurements and observations were obtained by densitometry and optical, scanning, and transmission electron microscopy. Based on experimental observations, it was found that hot compacts subjected to a single ECAP pass had significant microstructural refinement and subgrain formation, and significant density changes were not attained. Green compacts, on the other hand, were observed to lose coherency under ECAP. Three-dimensional finite element modeling of the ECAP process was also conducted to further elucidate the evolution of the extrusion process, and to understand how it affects plastic strains, porosity, and thermal distributions.

Feasibility of attaining uniform grain structure and enhanced ductility in aluminum alloy by employing a beveled punch in equal-channel angular pressing

“…The strain rate tensor (see equations [3][4][5] is the symmetrical part of the velocity gradient field, which can be calculated by partial derivation of the admissible velocity field corresponding to the flow function represented in equation 2. …”

“…Equal-channel angular pressing (ECAP) is one of the most important processes in order to produce nanostructured and ultrafine-grained materials [2][3][4][5]. In this process, a work-piece with circular or rectangular cross section is pressed using a plunger through a die containing a channel, bent through a sharp angle.…”

Microstructure, Mechanical Properties, and Thermal Stability of Al-Al2O3 Nanocomposites Consolidated by ECAP or SPS from Milled Powders

“…However, it must be kept in mind that, in spite of the denomination «ECAP-BP-RT», severe plastic deformation naturally induces thermal dissipation, and thus a non-negligible temperature rise. Based on numerical simulations of ECAP consolidation of precompacted 2124 Al alloy powder at room temperature, Elkhodary et al [22] estimated that even at a moderate pressing rate, the temperature can rise locally up to 216 • C. Since the load (and thus the stresses) are nearly ten times higher during ECAP-BP-RT than during ECAP-HT, while the shear strains, controlled by the die geometry, are similar, the plastic deformation energy (partly dissipated as heat_ is thus much higher in the first case. The temperature differential between ECAP-BP-RT and ECAP-HT is thus probably less than the 360 • C nominal temperature difference.…”

Fabrication of High Performance PM Nanocrystalline Bulk AA2124

“…Such cracks appear in the ECAP consolidates either due to opening of inherent defects in the HC or due to shear localization induced by poor lubrication and/or low forming temperature ( Ref 13,20,21). The uniform plastic deformation via ECAP one-pass and two-pass route (A) were conducted at 235 and 245°C, for the micro-and nanopowder HCs, respectively.…”