A study of size effect in micro-forming with micro-hardness tests

Chen, Fuh‐Kuo; Tsai, Jia-Wen

doi:10.1016/j.jmatprotec.2006.04.115

Cited by 50 publications

(29 citation statements)

References 4 publications

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“…To improve this identification, nanoindentation tests have been carried out. In fact, Chen et al [1] have shown that the theoretical proportionality between the hardness and the flow stress still exists in a specimen with downscaled dimensions.…”

Section: Nanoindentation Testsmentioning

confidence: 99%

Size effects on material behaviour in microforming

2008

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The development in a significant way of cold metal forming processes for very small mechanical components is limited by the understanding of geometric and material effects due to size reduction. Cylinder upsetting tests have been used to observe the so-called size effects in microforming. In this study, a set of experiments is performed where the diameter of the cylinder is scaling down from 5 mm to 1 mm. Cylinder upsetting tests were conducted by using a specific tool system for cold forging of micro parts, which have been developed in our laboratory. Compression tests were carried out by reducing the height of the cylinder by 70% at a constant rate of 0.03 mm/s and without lubricant. During the tests, the loading force is measured and the load-displacement curve can be plotted. The material parameters were identified by an inverse method.

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Section: Nanoindentation Testsmentioning

confidence: 99%

Size effects on material behaviour in microforming

2008

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“…As such, it is critical to investigate the size effect on the deformation behavior of materials. Many scholars have conducted investigation on the size effect phenomenon, including grain size effect, specimen size effect, and feature size effect [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

“…Chen and Tsai [7] performed a micro-hardness test to research the specimen size effect on mechanical properties of materials. The results showed that hardness and flow stress decreased with decreasing specimen size, which was in agreement with the theoretical proportionality between hardness and flow stress.…”

Section: Introductionmentioning

confidence: 99%

Feature Size Effect on Formability of Multilayer Metal Composite Sheets under Microscale Laser Flexible Forming

Liu

Zhang

Gau

et al. 2017

Metals

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Abstract:Multilayer metal composite sheets possess superior properties to monolithic metal sheets, and formability is different from monolithic metal sheets. In this research, the feature size effect on formability of multilayer metal composite sheets under microscale laser flexible forming was studied by experiment. Two-layer copper/nickel composite sheets were selected as experimental materials. Five types of micro molds with different diameters were utilized. The formability of materials was evaluated by forming depth, thickness thinning, surface quality, and micro-hardness distribution. The research results showed that the formability of two-layer copper/nickel composite sheets was strongly influenced by feature size. With feature size increasing, the effect of layer stacking sequence on forming depth, thickness thinning ratio, and surface roughness became increasingly larger. However, the normalized forming depth, thickness thinning ratio, surface roughness, and micro-hardness of the formed components under the same layer stacking sequence first increased and then decreased with increasing feature size. The deformation behavior of copper/nickel composite sheets was determined by the external layer. The deformation extent was larger when the copper layer was set as the external layer.

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“…Compared to micro sheet metal forming, few studies were focused on micro bulk metal forming [12][13]. In this investigation, the influence of specimen size and grain size on flow stress was studied.…”

Section: Introductionmentioning

confidence: 99%

Size effects on flow stress of C3602 in cylinder compression with different lubricants

et al. 2009

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Micro parts are more difficult to be formed than macro parts because of size effects. The size effects on the flow stress of copper alloy C3602 with different lubricants were studied. Specimens were heat treated at 350°C for 1 h and 700°C for 3 h in nitrogen atmosphere, respectively. The initial diameters of the specimens were varied from 5 to 1 mm with a height-to-diameter ratio h 0 /D 0 = 1.5. Cylinder compression was carried out in the lubrication condition with talc powder, without lubricant, with petroleum jelly, and with vegetable oil. The experiment was carried out at room temperature on a universal testing machine INSTRON 5569 with a strain rate of ε = 0.0025 /s. The results show that with the same lubricant, the yield strength decreases with a decrease in specimen size for the specimens annealed at 350°C for 1 h; however, it increases with a decrease in specimen size for the specimens annealed at 700°C for 3 h. The yield strength decreases with an increase in grain size. The influences of lubricants on yield strength become larger with miniaturization of the specimens.

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A study of size effect in micro-forming with micro-hardness tests

Cited by 50 publications

References 4 publications

Size effects on material behaviour in microforming

Size effects on material behaviour in microforming

Feature Size Effect on Formability of Multilayer Metal Composite Sheets under Microscale Laser Flexible Forming

Size effects on flow stress of C3602 in cylinder compression with different lubricants

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