Review: Modes and Processes of Severe Plastic Deformation (SPD)

Abstract

In this review, severe plastic deformation (SPD) is considered as a materials processing technology. The deformation mode is the principal characteristic differentiating SPD techniques from common forming operations. For large plastic strains, deformation mode depends on the distribution of strain rates between continuum slip lines and can be varied from pure shear to simple shear. A scalar, invariant, and dimensionless coefficient of deformation mode is introduced as a normalized speed of rigid rotation. On this basis, simple shear provides the optimal mode for structure modification and grain refinement, whereas pure shear is “ideal” for forming operations. Special experiments and SPD practice confirm this conclusion. Various techniques of SPD are classified and described in accordance with simple shear realization or approximation. It is shown that correct analyses of the processing mechanics and technological parameters are essential for the comparison of SPD techniques and the development of effective industrial technologies.

Semi-Continuous Equal-Channel Angular Extrusion and Rolling of AA5083 and AZ31 Alloys

“…The schematic shown in Figure 1 illustrates and explains the principle and tooling design of sc-ECAE. The original billet (2) is inserted into the vertical channel (8) of the die block (1). A horizontal channel (3) is formed between the die block (1) and a slider (5).…”

“…Among the numerous severe plastic deformation (SPD) techniques available [1], equal-channel angular extrusion (ECAE) is the most developed and promising for the fabrication of ultrafine-grained and bulk nanostructured materials. Presently, ECAE is the only SPD technique that found practical applications and, therefore, could be considered as an industrially mature technology [2].…”

High Performance Fine-Grained Biodegradable Mg-Zn-Ca Alloys Processed by Severe Plastic Deformation

“…Severe plastic deformation (SPD) resulting in remarkable microstructure refinement and effective texture modification concomitantly with strength enhancement appears as an ideal tool for the successful implementation of this strategy for Mg alloys. A broad variety of SPD techniques have been proposed for materials processing, microstructure refinement, and strengthening [16][17][18][19]. None of those can be considered universal.…”

Equal-Channel Angular Extrusion (ECAE): From a Laboratory Curiosity to an Industrial Technology

“…The original aim was the optimization of SPD using translation shear instead of twist, and the development of a related processing technique as an effective metal-forming operation. After extensive theoretical and experimental research, equal-channel angular extrusion (or pressing) (ECAE/P), providing a near "ideal" simple shear deformation mode for structure modification and optimal technological characteristics, was introduced [4]. In contrast to HPT, this technique was identified as "simple shear processing" [5].…”