Formation mechanism of inclined fatigue-cracks in ultrafine-grained Cu processed by equal channel angular pressing

Goto, Masahiro; Han, Seung Zeon; Yamamoto, Takaei; Kitamura, Junichi; Ahn, Jin-Ho; Yakushiji, Terutoshi; Kim, S.S.; Lee, J.

doi:10.1016/j.ijfatigue.2016.02.006

Cited by 14 publications

(13 citation statements)

References 49 publications

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“…1(b). obtained for the fatigue fracture behavior for UFG copper during tension [12] and the tension fracture of UFG nickel processed by HPT [13]. This finding demonstrates that the fracture mode is strongly associated with the simple shear texture produced by ECAP.…”

mentioning

confidence: 58%

“…Although several strategies have been proposed to improve the poor ductility of UFG materials [8][9][10], the fracture mechanism of UFG materials is at present not well defined [11]. For example, it was suggested that the fracture mechanism after necking depends mainly on the presence of inclusions [5] and recently shear fracture was reported as the common feature of UFG materials fabricated by equal-channel angular pressing (ECAP) [12] or high-pressure torsion (HPT) [13]. It is reasonable to anticipate, therefore, a correlation between the shear texture produced by ECAP or HPT processing and the subsequent fracture behavior.…”

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confidence: 99%

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Shear fracture mechanism in micro-tension of an ultrafine-grained pure copper using synchrotron radiation X-ray tomography

Guo

et al. 2017

Scripta Materialia

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In order to investigate the early fracture of ultrafine-grained (UFG) pure copper with a partially recrystallized microstructure and simple shear texture, the evolution of surface strain was measured using in situ micro-tension with digital image correlation.The spatial distribution of voids in tensile specimens was revealed after testing using synchrotron radiation X-ray tomography. The results show that the shear fracture behavior is associated with void evolution in UFG copper and this is strongly affected by the simple shear texture produced by equal-channel angular pressing (ECAP). The results have important implications for use in micro-forming.

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confidence: 58%

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confidence: 99%

Shear fracture mechanism in micro-tension of an ultrafine-grained pure copper using synchrotron radiation X-ray tomography

Guo

et al. 2017

Scripta Materialia

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“…Accordingly, a 45° inclined surface crack is subjected to both normal, σ (= 1), and shear stress, τ (= 1), as illustrated in Figs 10a and b. Noda et al [17] analyzed the SIFs of a semielliptical surface-crack subjected to modes I, II and III loading. The values of dimensionless SIF (DL-SIF), F I , F II , F III , for the current surface-crack were taken from Noda's solution calculated for Poisson's ratio: ν = 0.3.…”

Section: Discussionmentioning

confidence: 99%

“…where K i (α) is SIF along the crack front and K iE (α) is SIF of an elliptical crack [17]. The location along a crack front was defined by the eccentric angle of the ellipse, α, defined as the Figure 10: Inclined semi-elliptical surface cracks in a semi-infinite body subjected to tension load in the x-direction at infinity: (a) a model for a surface crack on the zx-plane;…”

Section: Discussionmentioning

confidence: 99%

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Relationship between shear plane of the final pressing and fatigue crack growth behaviour of round-bar specimens of CU processed by ECAP

Goto¹,

Yamamoto²,

Han³

et al. 2017

Int. J. CMEM

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The formation mechanism of inclined fatigue cracks in ultrafine-grained Cu processed by equal channel angular pressing was studied by using a smooth specimen with a small blind hole. The crack growth direction depended on the location of drilling hole along the circumferential direction of the round bar specimen and on the applied stress amplitudes. Although the low-cycle fatigue crack growth paths inclined 45° and 90° to the loading-axis were observed in the different locations on the surface, crack faces in these cracks were extended along one set of maximum shear stress planes, corresponding to the shear plane of the final processing. To study the crack growth behaviour, surface damage around the crack paths formed by the two-step fatigue stress tests was observed. Profile of crack face was examined, showing the aspect ratios (b/a) of b/a = 0.38 and 1.10 for the cracks with 45° and 90° inclined path directions with respect to the loading axis, respectively. The role of the microstructure and deformation mode at the crack-tip areas on the formation of crack paths parallel to the shear plane of the final pressing was discussed in terms of the microstructural evolution caused by cyclic stressing and the mixed-mode stress intensity factor.

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Fatigue Behaviors of Materials Processed by Planar Twist Extrusion

Ebrahimi

2017

Metall Mater Trans A

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Formation mechanism of inclined fatigue-cracks in ultrafine-grained Cu processed by equal channel angular pressing

Cited by 14 publications

References 49 publications

Shear fracture mechanism in micro-tension of an ultrafine-grained pure copper using synchrotron radiation X-ray tomography

Shear fracture mechanism in micro-tension of an ultrafine-grained pure copper using synchrotron radiation X-ray tomography

Relationship between shear plane of the final pressing and fatigue crack growth behaviour of round-bar specimens of CU processed by ECAP

Fatigue Behaviors of Materials Processed by Planar Twist Extrusion

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