Effects of thickness and surface roughness on mechanical properties of aluminum sheets

Suh, Chang Hee; Jung, Yun-Chul; Kim, Young Suk

doi:10.1007/s12206-010-0707-7

Cited by 57 publications

(23 citation statements)

References 16 publications

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“…7, the true fracture strain of the ARB-processed foils increases from 0.4 to 1.5 after two AR passes. At this point, the tensile stress increases by 21% and the ductility of the foils is much greater than that Fig.11-Thickness size effect during tensile process, (a) for Al 6K21-T4 with coarse grains, [48] (b) for annealed pure Cu foils, [8] and (c) for the samples in current experiments.…”

Section: Thickness Size Effect In Nanostructured Laminate Foilsmentioning

confidence: 72%

“…As shown in Fig. 11a, [48] for annealed Al 6K21-T4 sheets of grain size 40 m, as the thickness of the sheet is reduced from 1600 m to 400 m, the engineering fracture strain is reduced from 0.25 to 0.15 and the tensile stress also decreases slightly. A similar phenomenon was also observed by Simons et al [8] who carried out tensile tests on thin rolled & annealed copper foils of different thicknesses.…”

Section: Thickness Size Effect In Nanostructured Laminate Foilsmentioning

confidence: 88%

“…[22] Suh et al [48] found that the tensile strength and ductility of Al 6K21-T4 sheets decreased almost linearly with a reduction in thickness, when the thickness was less than a critical value.…”

Section: Thickness Size Effect In Nanostructured Laminate Foilsmentioning

confidence: 99%

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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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Section: Thickness Size Effect In Nanostructured Laminate Foilsmentioning

confidence: 72%

Section: Thickness Size Effect In Nanostructured Laminate Foilsmentioning

confidence: 88%

See 1 more Smart Citation

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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“…That is to say, when a decreases, the effect of the surface on the mechanical properties is enhanced. Suh et al [46] found that the tensile strengths of Al 6K21-T4 sheets decreased almost linearly with thickness reduction when the thickness was reduced below a critical value. The previous discussion on the effect of different parameters on the material strength, such as deformation of secondary phase particles, sheet thickness, precipitation and reduction, can be expressed in the form of Eq.…”

Section: Strength Of As-rolled and Aged Sheetsmentioning

confidence: 99%

Mechanical properties of Al–Mg–Si alloy sheets produced using asymmetric cryorolling and ageing treatment

Tieu

Lü

et al. 2013

Materials Science and Engineering: A

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An asymmetric cryorolling technique was used to reduce the thickness of an Al-Mg-Si alloy sheet from 1.5 mm to 0.19 mm. The samples were subsequently aged for 48 h at 100 degrees celcius. The hardness and tensile strength of both rolled and aged sheets increased with the number of passes up to the sixth pass, but the tensile stress decreased after the seventh pass. Investigation of the microstructure of the sheets showed that the grain size after seven passes was about 235 nm and revealed the presence of Fe-Cr-Mn-Si particles in the samples. The deformation of Fe-Cr-Mn-Si particles and sheet thickness affects the ductility when the sheet thickness is less than 0.4 mm, and the strength when the thickness is less than 0.2 mm. An asymmetric cryorolling technique was used to reduce the thickness of an Al-Mg-Si alloy sheet from 1.5 mm to 0.19 mm. The samples were subsequently aged for 48 h at 100 1C. The hardness and tensile strength of both rolled and aged sheets increased with the number of passes up to the sixth pass, but the tensile stress decreased after the seventh pass. Investigation of the microstructure of the sheets showed that the grain size after seven passes was about 235 nm and revealed the presence of Fe-CrMn-Si particles in the samples. The deformation of Fe-Cr-Mn-Si particles and sheet thickness affects the ductility when the sheet thickness is less than 0.4 mm, and the strength when the thickness is less than 0.2 mm.

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“…There is no significant difference for the ratio between the gauge length to gauge width between the ECAP and HPT tensile specimens and the major difference is the specimen thickness. It was reported that the yield and tensile strengths decreased when the number of grains over the thickness was decreased and the ductility also decreased when reducing the thickness [23,24]. Obviously considering the effect of specimen thickness on mechanical properties, it is reasonable to assume that specimen size has certain contributions to the low elongations in HPT processed AZ31 at 623 and 673 K with different test strain rates.…”

Section: Discussionmentioning

confidence: 99%

An evaluation of high temperature tensile properties for a magnesium AZ31 alloy processed by high-pressure torsion

Huang¹,

Pereira²,

Figueiredo³

et al. 2015

LoM

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A magnesium alloy AZ31 was processed by high-pressure torsion (HPT) at room temperature. Microstructure investigations show the material has a grain size as fine as ~450 nm after 5 turns of HPT processing. X-ray texture measurements show most grains have the {0001} fibre, with their c-axis parallel to the HPT torsion axis. Tensile specimens were cut from HPT disc and pulled to failure over a range of strain rates (4.5×10 ) at temperatures of 623 and 673 K. The tensile elongations from HPT specimens are lower than for published results using equal-channel angular processing (ECAP) specimens although AZ31 has a finer grain size after HPT than after ECAP. The reasons for the lower elongations in HPT specimens are related to the thermal stability of the processed microstructure, the texture components and the tensile specimen size. Earlier investigations confirmed there was significant grain growth at 623 and 673 K in HPT samples, which would contribute to the low ductility of AZ31 in tensile testing. The main {0001} fibre in HPT samples means in tensile specimens most grains have their basal plane parallel to the surface of the tensile specimen, leading to the low ductility because the critical resolved shear stress does not operate on the basal plane due to the small Schmid factor that is nearly zero. The tensile specimen thickness in HPT is thinner than in ECAP and it is known that the ductility decreases when reducing the specimen thickness.Keywords: AZ31, high-pressure torsion, magnesium alloy, tensile properties Оценка высокотемпературных механических свойств при растяжении магниевого сплава AZ31, подвергнутого кручению под высоким давлениемМагниевый сплав AZ31 был подвергнут кручению под высоким давлением (КВД) при комнатной температуре. Ми-кроструктурные исследования показали, что материал имеет размер зерен около 450 нм после 5 оборотов КВД. Из-мерения текстуры рентгенографическим методом показали, что большинство зерен имеют волокнистую текстуру {0001} с осью c, параллельной оси кручения. Из дисков, подвергнутых КВД, вырезаны образцы для испыта-ний растяжением, которые испытаны до разрушения в интервале скоростей деформации (4.5×10 ) при температурах 623 и 673 K. Значения удлинения при растяжении образцов после КВД оказались ниже, чем опубликованные значения, полученные на образцах, подвергнутых равноканальному угловому прессованию (РКУП), хотя сплав AZ31 имеет меньший размер зерен после КВД, чем после РКУП. Причина более низких значений удлинения образцов после КВД связана с термической стабильностью микроструктуры, текстурными компонентами и размерами образцов для растяжения. Прежние исследования показали, что в образцах после КВД имеет место зна-чительный рост зерен при 623 и 673 K; это вызывает снижение пластичности сплава AZ31 при растяжении. Главная текстурная компонента {0001} в образцах после КВД означает, что в образцах для растяжения большинство зерен имеет ориентацию базальной плоскости, параллельную поверхности образца. Это также приводит к снижению пластичности, так как...

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Effects of thickness and surface roughness on mechanical properties of aluminum sheets

Cited by 57 publications

References 16 publications

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

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

Mechanical properties of Al–Mg–Si alloy sheets produced using asymmetric cryorolling and ageing treatment

An evaluation of high temperature tensile properties for a magnesium AZ31 alloy processed by high-pressure torsion

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