Formation process of shear bands and protrusions in ultrafine grained copper under cyclic stresses

Goto, Masahiro; Han, Sen; Yakushiji, Terutoshi; Lim, Cha-Yong; Kim, S.S.

doi:10.1016/j.scriptamat.2006.03.001

Cited by 55 publications

(39 citation statements)

References 21 publications

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“…These structural features of the SBs characterized by the present study are consistent with those reported in the literature. 9,11,14,16,18) Changes in grain size and grain morphology of the fatigued specimens were observed using the EBSD method. Grain maps obtained from an as-ECAPed material and a specimen Fig.…”

Section: Cyclic Stress-strain Responsementioning

confidence: 99%

Cyclic Deformation Behavior of Ultra-Fine Grained Copper Produced by Equal Channel Angular Pressing

et al. 2009

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Cyclic deformation behavior of ultra-fine grained (UFG) Cu of 99.99% purity processed by equal-channel angular pressing was investigated. In tension-compression fatigue tests under strain control, UFG Cu showed cyclic softening. Shear bands were formed along the direction inclined by about 45 from the loading axis. Observations using an electron backscattering diffraction technique and transmission electron microscopy revealed that local grain growth took place in the shear bands and overall grains elongated along the shear direction. Cyclic softening can be understood as a result of dynamic grain coarsening occurred intensively in the strain localized shear bands.

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Section: Cyclic Stress-strain Responsementioning

confidence: 99%

Cyclic Deformation Behavior of Ultra-Fine Grained Copper Produced by Equal Channel Angular Pressing

et al. 2009

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“…Agnew and his co-workers [22] later in 1999 further confirmed such a phenomenon, i.e., cyclic softening response following cyclic hardening, reported in [20]. Later observations of various extent of cyclic softening were reported by a number of other researchers, i.e., reference [23][24][25][26][27][28][29][30][31][32][33][35][36][37][38]56,58]. It should be noted that these reports are largely based on high purity copper.…”

Section: Overview Of the Cyclic Deformation Behavior Of Spded Metalsmentioning

confidence: 63%

“…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%

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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“…3 shows the TEM micrographs of as-ECAPed and post-fatigued samples. In spite of very low applied stress amplitude ( a = 100 MPa: about 25% of tensile strength) under stress controlled fatigue, coarsened grains embedded within the original fine grain/cell regions are generated after 3.1x10 6 repetitions. Evidently, purity and fatigue time might be important in determining the coarsening of microstructure.TEM micrograph of post fatigued specimen indicated grain coarsening and decrease in dislocation density inside coarsened grains.…”

Section: Fatigue Characteristics and Surface Damage Under Cyclic Strementioning

confidence: 99%

“…Regarding the fatigue of UFG materials, most studies have concentrated on cyclic deformation, fatigue life, surface damage formation and underlying microstructural mechanisms [1][2][3][4][5][6]. Since the fatigue life of machine components and structures are mainly controlled by the growth life of a fatigue crack, the crack growth behavior should be clarified for the design of safe machine components and structures.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of crack growth rate and growth model of ultrafine grained copper

Goto

Han

Euh

et al. 2011

Computational Methods and Experimental Measurements XV

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High-cycle fatigue tests were carried out on smooth specimens of ultrafine grained (UFG) copper produced by equal channel angular pressing for 12 passes. The growth behavior of a small surface-crack was monitored. A major crack, which led to the final fracture of the specimen, initiated from shear bands (SBs) at an early stage of stressing. Different tendencies of growth behavior occurred depending on the ranges of crack length. To understand the changes in growth rate and fracture surface morphologies, a quantitative model describing a crack growth mechanism were developed considering the reversible plastic zone size at a crack tip. In addition, the crack growth rate of UFG copper was evaluated by applying the small-crack growth raw.

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Formation process of shear bands and protrusions in ultrafine grained copper under cyclic stresses

Cited by 55 publications

References 21 publications

Cyclic Deformation Behavior of Ultra-Fine Grained Copper Produced by Equal Channel Angular Pressing

Cyclic Deformation Behavior of Ultra-Fine Grained Copper Produced by Equal Channel Angular Pressing

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

Evaluation of crack growth rate and growth model of ultrafine grained copper

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