Geometry and grain size effects on the fracture behavior of sheet metal in micro-scale plastic deformation

Fu, Ming; Chan, Wai Ming

doi:10.1016/j.matdes.2011.06.039

Cited by 198 publications

(74 citation statements)

References 41 publications

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“…It is found that the number of micro-dimples decreases with the decreasing T/D. This is consistent with prior studies [15]. The grain boundary fraction in the materials increase with the value of T/D and because the grain boundaries act as obstacles to dislocation motion, the stresses concentrate at or near grain boundary regions and cause micro-voids and micro-dimples formation consequently in the deformation process.…”

Section: The Effect Of T/d On Fracture Behavioursupporting

confidence: 91%

“…Liu et al [14] developed a constitutive model considering the grain boundary strain hardening. Fu et al [15] studied the size effect on fracture behavior of the annealed copper foils with different thicknesses and grain sizes by tensile tests, and they found that the number of micro-voids as well as the fracture stress and strain decrease with T/D. Hmida et al [16] conducted the single point incremental forming process of copper foils with different grain sizes, and it is observed the formability decreases with T/D.…”

Section: Introductionmentioning

confidence: 99%

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Grain size effect of thickness/average grain size on mechanical behaviour, fracture mechanism and constitutive model for phosphor bronze foil

Fang

Jiang

Wang

et al. 2015

Int J Adv Manuf Technol

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X. (2015). Grain size effect of thickness/average grain size on mechanical behaviour, fracture mechanism and constitutive model for phosphor bronze foil. International Journal of Advanced Manufacturing Technology, 79 (9-12), 1905Technology, 79 (9-12), -1914 Grain size effect of thickness/average grain size on mechanical behaviour, fracture mechanism and constitutive model for phosphor bronze foil AbstractSize effects play a significant role in microforming process, and any dimensional change can have a great impact on materials' mechanical properties. In this paper, the size effects on deformation behaviour and fracture of phosphor foil were investigated in the form of grain size effect: the ratio of materials' thickness (T) to average grain size (D) by micro tensile tests. The ratio was designed to be closed to but larger than, less than and equal to 1, respectively. The results show that the amount of plastic deformation decreases with the decrease of the ratio of T/D, which indicates that the grain size plays a significant role and grain deformation modes differ when the ratio changes. It is also found that their fractograph reflects different features in terms of micro-dimples and cleavage planes, further demonstrating that when T/D >1, its materials have a tendency to fracture ductilely, while materials would like to conduct brittle fracture when T/D Grain size effect of thickness/average grain size on mechanical behaviour, fracture mechanism and constitutive model for phosphor bronze foil Abstract: In this paper, the size effects on deformation behaviour and fracture of phosphor foil were investigated in terms of the ratio of materials' thickness (T) to average grain size (D) by micro tensile tests. The results show that the amount of plastic deformation decrease with the decrease of the ratio of T/D, which indicates that the grain size plays a significant role and grain deformation modes differ when the ratio changes. It is also found that their fractograph reflect different features in terms of micro-dimples and cleavage planes, further demonstrating that when T/D>1, its materials have a tendency to fracture ductilely, while materials would like to conduct brittle fracture when T/D<1. So the ratio of T/D which is close to 1 can be regards as the divide of ductile fracture and brittle fracture. For T/D<1, a new constitutive model is proposed based on the classic composite model. The model's results are compared with the experimental ones and the efficiency of the developed models is verified.

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Section: The Effect Of T/d On Fracture Behavioursupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Grain size effect of thickness/average grain size on mechanical behaviour, fracture mechanism and constitutive model for phosphor bronze foil

Fang

Jiang

Wang

et al. 2015

Int J Adv Manuf Technol

View full text Add to dashboard Cite

show abstract

“…[8] They found that when the foil thickness was reduced from 250 μm to 10 μm, the fracture strain decreased from approximately 0.2 to 0.002 for cold-rolled foils and from 0.35 to 0.15 for annealed foils respectively. To study the size effects on fracture, Fu and Chan [9] conducted tensile tests on annealed pure copper foils with varying thicknesses and grain sizes. It was found that the flow stress, fracture stress/strain and the number of microvoids on the fracture surface decreased with decreasing specimen size/grain size ratio.…”

Section: Introductionmentioning

confidence: 99%

High Strength and Ductility of Ultrathin Laminate Foils Using Accumulative Roll Bonding and Asymmetric Rolling

Tieu

Hadi

et al. 2014

Metall Mater Trans A

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As product miniaturization is becoming widely popular, many microparts are being produced by microforming of sheets/foils, whose strength needs to be able to maintain structural stability of the microcomponents. In addition, their strength and ductility of foils generally reduce with a reduction in the thickness due to the size effect. In this paper, we report the fabrication of an aluminum laminate foil using a combined process of accumulative roll bonding (ARB) and asymmetric rolling (AR). It was found that this improves both strength and ductility. TEM results show that the laminate structures produced by ARB develop an inhomogeneous microstructure with nanoscale grains and abnormal coarsening in some grains during AR processing. Both these effects result in an improved ductility and strength. Using these rolled products, micro-cups of very small wall thickness/cup diameter ratio (1/200) have been successfully fabricated by micro-deep drawing without the need for annealing. KeywordsAluminum alloy; Nanostructure; Abnormal grain growth; Rolling; Deep drawing; Ultrathin laminate foil Disciplines Engineering | Science and Technology Studies Publication DetailsYu, H., Tieu, A. Kiet., Hadi, S., Lu, C., Godbole, A. & Kong, C. (2015). High strength and ductility of ultrathin laminate foils using accumulative roll bonding and asymmetric rolling. Metallurgical Abstract: As product miniaturization is becoming widely popular, many microparts are being produced by microforming of sheets/foils, whose strength needs to be able to maintain structural stability of the micro components. In addition, their strength and ductility of foils generally reduces with a reduction in the thickness due to the size effect. In this paper, we report the fabrication of an aluminum laminate foil using a combined process of Accumulative Roll Bonding (ARB) and Asymmetric Rolling (AR). It was found that this improves both strength and ductility. TEM results show that the laminate structures produced by ARB develop an inhomogeneous microstructure with nanoscale grains and abnormal coarsening in some grains during AR processing. Both these effects result in an improved ductility and strength. Using these rolled products, micro-cups of very small wall thickness/cup diameter ratio (1/200) have been successfully fabricated by micro deep drawing without the need for annealing.

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“…It is difficult to fabricate the tiny tools and handle the tiny workpiece. The increase of friction force and the decrease of strength and ductility are resulted with scaling down to micro scale because of the tribological and grain size effects [6,7]. These size effects cause the low formability in micro forming.…”

Section: Introductionmentioning

confidence: 99%

Study on micro extra deep drawing process with ultrahigh fluid pressure and press motion controls

Sato

Kondo

Manabe

et al. 2015

MATEC Web of Conferences

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Abstract.A novel micro extra deep drawing process with ultrahigh fluid pressure and press motion controls are developed. A space between the blank and 1 st punch is made by the press motion at the 2 nd drawing stage and the ultrahigh pressure is applied so as to be disappeared this space. It can enhance a material flow into the die cavity because the ultrahigh pressure acts on the blank at side wall. In addition, a friction holding effect occurs, which prevents the thickness reduction at punch shoulder and side wall. Due to these mechanisms, the micro cup with aspect ratio of 2.0 can be successfully fabricated by micro extra deep drawing in FE simulation, although it cannot be fabricated by conventional micro deep drawing and micro hydromechanical deep drawing.

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Geometry and grain size effects on the fracture behavior of sheet metal in micro-scale plastic deformation

Cited by 198 publications

References 41 publications

Grain size effect of thickness/average grain size on mechanical behaviour, fracture mechanism and constitutive model for phosphor bronze foil

Grain size effect of thickness/average grain size on mechanical behaviour, fracture mechanism and constitutive model for phosphor bronze foil

High Strength and Ductility of Ultrathin Laminate Foils Using Accumulative Roll Bonding and Asymmetric Rolling

Study on micro extra deep drawing process with ultrahigh fluid pressure and press motion controls

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