Formation mechanism of lamellar chips during machining of bulk metallic glass

Jiang, Minqiang; Dai, L.H.

doi:10.1016/j.actamat.2009.02.031

Cited by 84 publications

(36 citation statements)

References 40 publications

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“…More and more works [12,15,16,[18][19][20][21]31,47,49,59] have indicated that the shear-banding formation in BMGs is a coupled thermomechanical process, dominated by local free-volume softening and assisted by thermal softening. In order to capture such a coupling nature, we replace the shear stress softening relation in Eq.…”

Section: Shear-band Dissipation Energy and Toughnessmentioning

confidence: 99%

“…Here, we concentrate on the process of shear-band evolution/propagation at the stage of growth in a local plastic region until it matures. It is well known that the shear-banding process is a dissipation system [2,10,15,16,[31][32][33]37,53]. In addition to conventional thermal/energy and momentum/viscous dissipation, the freevolume dissipation should be involved here due to the unique atomic structure of BMGs.…”

Section: Local Evolution Model For Shear Bandmentioning

confidence: 99%

“…Therefore, it is still necessary to understand the nature of the shear-banding process in these glassy alloys. In this respect, areas of interest involve the geometrical configuration of shear bands, such as thickness [2,11,12], length and spacing [10,[13][14][15][16], the structural change [17][18][19] and temperature rise [19][20][21] that occurs in shear bands, the propagating mode [19,[22][23][24][25][26] and velocity of shear bands [27][28][29], and the deformation accommodated by shear bands, including plastic strain and its strain rate [30,31]. In fact, the critical plastic energy C c dissipated in a shear band prior to catastrophic fracture is of central importance in the development of ductile BMGs.…”

Section: Introductionmentioning

confidence: 99%

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Shear-band toughness of bulk metallic glasses

Jiang

Dai

2011

Acta Materialia

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Dynamic "forced" shear and quasi-static tensile tests were performed on a typical Vitreloy 1 bulk metallic glass (BMG). The nanoscale shear band is found to initiate in a local plastic region, then propagates with a well-defined front. A theoretical model that takes into account momentum, energy and free-volume balance is developed to quantitatively describe the dissipation system of shear-band propagation in the local plastic region. The analytical expressions for shear-localization time, shear-band thickness and critical energy dissipated within the band are obtained. Calculations demonstrate that the shear-band propagation process is dominated by the free-volume softening, rather than the thermal softening. The latter increases the band thickness slightly but decreases the corresponding critical dissipation energy somewhat. The concept of shear-band toughness is further introduced to measure the inherent resistance capability of materials to the propagation of shear bands in BMGs. These results assist in more comprehensively understanding the evolution mechanism of the shear bands, and in guiding alloy design to enhance the toughness of BMGs.

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Section: Shear-band Dissipation Energy and Toughnessmentioning

confidence: 99%

Section: Local Evolution Model For Shear Bandmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Shear-band toughness of bulk metallic glasses

Jiang

Dai

2011

Acta Materialia

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“…Some of the specific observations associated with the chip formation of BMG include, chip light emissions, and oxidation and crystallisation of the chips [4,5]. Repeated shear bands in the primary shear zone were observed during chip formation of BMG, in the work of [6]. Very limited study on the effect of machining parameters on surface morphology and machinability studies were also mentioned in [7] and [8].…”

Section: Introductionmentioning

confidence: 99%

Investigation on chip formation and surface morphology in orthogonal machining of Zr-based bulk metallic glass

Dhale

Banerjee

Singh

et al. 2019

Manufacturing Letters

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Investigation on chip formation and surface morphology in orthogonal machining of Zr-based bulk metallic glass. Manufacturing Letters, Elsevier, 2019, 19, pp. AbstractThis work presents the preliminary investigation on the orthogonal machining of Zr-based bulk metallic glass. Influence of machining parameters on the chip formation mechanisms has been analyzed. The SEM images of the chip surfaces have been taken for this purpose. It has been observed that at lower speed and uncut chip thickness, the individual serrated sections of chips develop shear bands in the surface. At higher speed and uncut chip thickness, these shear bands aggravate and leads to form fragmented surfaces. Degree of segmentation and serration spacing of chips were analyzed and compared with the morphology of the machined surface.Hence, the primary goal of this work is to understand the shear band evolution during chip formation of BMGs at very low cutting speeds and uncut chip thickness. The chip morphology, degree of segmentation, serration spacing and surface morphology has been investigated on Zr-based BMG.

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“…The formation of continuously serrated chip flow has been extensively studied [4][5][6][7]. It is found that the emergence of serrated chip flow is related to the cracking initiated at the free surface [6,8] or the shear banding occurred in the primary shear zone (PSZ) [9][10][11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Onset and evolution of discontinuously segmented chip flow in ultra-high-speed cutting Ti-6Al-4V

et al. 2016

Int J Adv Manuf Technol

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Increasing the cutting speed to an ultra-high level usually gives rise to a chip flow transition from continuously serrated to discontinuously segmented, which is one of the most fundamental and challenging problems in metal cutting. In this work, we experimentally performed the ultra-high-speed cutting on Ti-6Al-4V with a maximum cutting speed of 210 m/s, focusing on the physical phenomena accompanying the discontinuously segmented chip flow. It reveals that the discontinuously segmented chip flow can be attributed to the shear fracture induced by the fully matured shear banding, and there exists a ductile-brittle transition of the shear fracture as the cutting speed increases to an ultra-high level. In addition, the critical condition for the onset of segmented chip flow is presented using the momentum diffusion-based shear band evolution model, which gives good prediction for the chip segmentation.

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Formation mechanism of lamellar chips during machining of bulk metallic glass

Cited by 84 publications

References 40 publications

Shear-band toughness of bulk metallic glasses

Shear-band toughness of bulk metallic glasses

Investigation on chip formation and surface morphology in orthogonal machining of Zr-based bulk metallic glass

Onset and evolution of discontinuously segmented chip flow in ultra-high-speed cutting Ti-6Al-4V

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