Monotonic and cyclic deformation behaviour of ultrafine-grained aluminium

May, Johannes; Amberger, D.; Dinkel, Markus; Höppel, Heinz Werner

doi:10.1016/j.msea.2006.12.177

Cited by 27 publications

(23 citation statements)

References 21 publications

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“…41) Therefore, the obtained average grain size of 1.3 µm in the present study is reasonably larger than that of commercially pure Al fabricated by the same ECAP condition. 28,29) Nevertheless, we have chosen high purity Al for the purpose of avoiding the effects of impurities and investigating the primary mechanical and physical properties of Al.…”

Section: Methodsmentioning

confidence: 99%

“…Since UFG Al generally shows shorter fatigue life than CG Al at low-cycle fatigue tests, 28,29,31) it is reasonable that UFG Al reached stress saturation at smaller cumulative plastic strain than CG Al. No cracks were observed on the surface of specimens after the fatigue tests mentioned above.…”

Section: Methodsmentioning

confidence: 99%

“…2831) For the low-cycle tests, it is also known that UFG pure aluminum shows hardening followed by softening 28,29) and distinct fatigue dislocation structure has not been observed in grains at room temperature. 28) In contrast, single-crystalline and CG Al show initial hardening, softening and secondary hardening 3234) with the formation of characteristic dislocation structure such as vein, 35,36) wall, 35,36) labyrinth 32,35,37) and cell 28,34) structures.…”

Section: )mentioning

confidence: 99%

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Stability of Fatigued Dislocation Wall Structure in Coarse-Grained and Ultrafine-Grained Aluminum against Monotonic Tensile Deformation

et al. 2013

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Coarse-grained (CG) and ultrafine-grained (UFG) pure aluminum samples fabricated by equal channel angular pressing (ECAP) were cyclically deformed at 77 K under constant plastic strain amplitude. Monotonic tensile tests were performed at 300 and 77 K soon after the fatigue tests. In spite of the increase in the tensile strength of fatigued CG Al, tensile ductility decreased remarkably in comparison to that of as-annealed CG Al. On the other hand, the ultimate tensile strength (UTS) and tensile ductility of UFG Al were much higher at 77 K than those at 300 K. Furthermore, UFG Al at 77 K maintained high UTS and high tensile ductility even after fatigue tests. Microstructural observation has revealed that dislocation wall structure formed in fatigued CG Al persists after the monotonic tensile tests. However, dislocation wall structure formed in fatigued UFG Al disappeared during early stages of monotonic tensile tests at both 300 and 77 K. These results indicate that the dislocation wall structure in UFG Al is unstable against succeeding monotonic tensile deformation.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: )mentioning

confidence: 99%

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Stability of Fatigued Dislocation Wall Structure in Coarse-Grained and Ultrafine-Grained Aluminum against Monotonic Tensile Deformation

et al. 2013

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“…Many of the reports on the cyclic deformation behavior of SPDed metals have been based on metals processed by ECAP, e.g., for high purity copper [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38], technical purity copper [33,[39][40][41][42][43][44], aluminium and aluminum alloys [45][46][47][48][49][50][51], commercial purity titanium [52], IF steel [53,54], and α-brass [55]. There are also reports, albeit fewer in quantity, based on products of different techniques, such as high purity copper processed by HPT [36], high purity copper processed by ARB [56,57], and aluminum and aluminum alloys processed by cryogenic rolling [58,59].…”

Section: Overview Of the Cyclic Deformation Behavior Of Spded Metalsmentioning

confidence: 99%

“…A transition from cyclic hardening response to cyclic softening response with increasing applied plastic strain amplitudes or increasing cyclic stress amplitudes can be observed in many of the cases with technical purity copper [40][41][42], and that of aluminum alloys [45][46][47][49][50][51]. It is worth mentioning that Kunz et al [44] have reported that cyclic softening is observed only in strain controlled tests, whereas load controlled tests generally yield cyclic hardening or cyclic saturation response.…”

Section: Overview Of the Cyclic Deformation Behavior Of Spded Metalsmentioning

confidence: 99%

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

Kwan

Wang

2012

Metals

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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.

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Macro‐ and Nanomechanical Properties and Strain Rate Sensitivity of Accumulative Roll Bonded and Equal Channel Angular Pressed Ultrafine‐Grained Materials

et al. 2011

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Ultrafine-grained (UFG) metals produced by severe plastic deformation (SPD), i.e. equal channel angular pressing (ECAP) or accumulative roll bonding (ARB), exhibit outstanding mechanical properties. They show a high strength often paired with good ductility under monotonic loading and a strain rate sensitive behavior. [1] This is not only true for pure metals like aluminium of technical purity but also for other materials. [2][3][4][5][6] The enhanced strain rate sensitivity (SRS) is widely accepted to be a key issue for the improved ductility of UFG metals.Both processes are in principle suitable for industrial application. However, the ARB process is advantageous due to the possibility of continuous processing of large sheets. It is of interest if the mechanical behavior and especially the strain rate sensitivity SRS depend on the process of SPD. Such comparisons have already been performed for ECAP and high pressure torsion (HPT) by Alkorta et al. [7] on bcc metals. For fcc metals, the correlation of the microstructures and mechanical properties terms of strain rate sensitivity is up to now not completely understood.In this context UFG aluminium of technical purity (Al99.5) was produced with ECAP and ARB up to almost identical effective plastic strains of e ARB ¼ 6.4 and e ECAP ¼ 6.3. The mechanical properties as well as the strain rate sensitivity were investigated. Significant differences were observed and are discussed in terms of microstructural differences in this paper.

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Monotonic and cyclic deformation behaviour of ultrafine-grained aluminium

Cited by 27 publications

References 21 publications

Stability of Fatigued Dislocation Wall Structure in Coarse-Grained and Ultrafine-Grained Aluminum against Monotonic Tensile Deformation

Stability of Fatigued Dislocation Wall Structure in Coarse-Grained and Ultrafine-Grained Aluminum against Monotonic Tensile Deformation

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

Macro‐ and Nanomechanical Properties and Strain Rate Sensitivity of Accumulative Roll Bonded and Equal Channel Angular Pressed Ultrafine‐Grained Materials

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