The Cyclic Deformation Behavior of Severe Plastic Deformation (SPD) Metals and the Influential Factors

Abstract

Abstract:A deeper understanding of the mechanical behavior of ultra-fine (UF) and nanocrystalline (NC) grained metals is necessary with the growing interest in using UF and NC grained metals for structural applications. The cyclic deformation response and behavior of UF and NC grained metals is one aspect that has been gaining momentum as a major research topic for the past ten years. Severe Plastic Deformation (SPD) materials are often in the spotlight for cyclic deformation studies as they are usually in the form of bulk work pieces and have UF and NC grains. Some well known techniques in the category of SPD processing are High Pressure Torsion (HPT), Equal Channel Angular Pressing (ECAP), and Accumulative Roll-Bonding (ARB). In this report, the literature on the cyclic deformation response and behavior of SPDed metals will be reviewed. The cyclic response of such materials is found to range from cyclic hardening to cyclic softening depending on various factors. Specifically, for SPDed UF grained metals, their behavior has often been associated with the observation of grain coarsening during cycling. Consequently, the many factors that affect the cyclic deformation response of SPDed metals can be summarized into three major aspects: (1) the microstructure stability; (2) the limitation of the cyclic lifespan; and lastly (3) the imposed plastic strain amplitude.

High cycle fatigue behavior of Al1070 alloy severely deformed by equal channel angular pressing process

“…The cyclic deformation responses of UFG materials have been categorized into three basic factors which consist of microstructure stability of the initial microstructure, cyclic lifespan and applied cyclic plastic strain level. 14 For Al1070, it seems changing the driving force for the grain coarsening phenomenon is more important than other factors. 14 The microstructure stability can affect the cyclic deformation response of the UFG metals by affecting the extent of grain coarsening.…”

“…14 For Al1070, it seems changing the driving force for the grain coarsening phenomenon is more important than other factors. 14 The microstructure stability can affect the cyclic deformation response of the UFG metals by affecting the extent of grain coarsening. 14…”

“…14 The microstructure stability can affect the cyclic deformation response of the UFG metals by affecting the extent of grain coarsening. 14 Figure 9 shows the cleavage and dimple areas at stress amplitude a of 80 MPa for ECAP-ed sample after 4 passes. Figure 9(a) shows the dimple area, represented by striations, where the path of crack propagation is evident.…”

“…[1][2][3][4][5][6] The cyclic deformation response and behavior of SPD-ed materials in the form of bulk were among the major research subjects for last decade. [7][8][9][10][11][12][13][14] The ultra-fine grained (UFG) metals produced by SPD techniques exhibit an enhanced high cycle fatigue at small strain amplitudes, but a reduced low cycle fatigue life occurs at relatively large strains. 11 It is believed that fatigue damage behavior depends on the cracking mechanisms and the formation of shear bands on surface.…”

Analyzing the Deformation and Fracture of Bioinert Titanium, Zirconium and Niobium Alloys in Different Structural States by the Use of Infrared Thermography

“…The SPD treatment used to obtain UFG titanium and its alloys, as well as the microstructure and physical and mechanical properties of these materials have been thoroughly studied [3]; however, research continues [5]. The mechanisms of plastic deformation and the fracture of titanium alloys under various combinations and profiles of thermal and mechanical stresses are being studied [6][7][8].…”