Change of Elastic Constants of Pure Iron Deformed by Cold Rolling

Benito, J.A.; Jorba, Jordi; Roca, A.

doi:10.4028/www.scientific.net/msf.426-432.4435

Cited by 5 publications

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“…This will result in smaller regions of low dislocation density. There will be more interactions between dislocations, and dislocation segment length will be smaller although the dislocation density increases, which results in a higher elastic modulus32. Fig.…”

Section: Resultsmentioning

confidence: 99%

“…During the cold rolling process, the elastic modulus may change slightly with the deformation. Benito et al32 studied the change in elastic modulus of pure iron deformed by cold rolling. They also found the above trends.…”

Section: Resultsmentioning

confidence: 99%

“…In asymmetrically rolled sheets with a 91.8% reduction in thickness at 300°C, fine grains with an average size of 1 μm have been developed27. The AR technique has also been used to produce multilayer metal products272829303132. Zu et al2829 used AR to produce bimetallic (Al/Cu) clad sheets.…”

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confidence: 99%

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Fabrication of ultra-thin nanostructured bimetallic foils by Accumulative Roll Bonding and Asymmetric Rolling

Lü

Godbole

et al. 2013

Sci Rep

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This paper reports a new technique that combines the features of Accumulative Roll Bonding (ARB) and Asymmetric Rolling (AR). This technique has been developed to enable production of ultra-thin bimetallic foils. Initially, 1.5 mm thick AA1050 and AA6061 foils were roll-bonded using ARB at 200°C, with 50% reduction. The resulting 1.5 mm bimetallic foil was subsequently thinned to 0.04 mm through four AR passes at room temperature. The speed ratio between the upper and lower AR rolls was 1:1.3. The tensile strength of the bimetallic foil was seen to increase with reduction in thickness. The ductility of the foil was seen to reduce upon decreasing the foil thickness from 1.5 mm to 0.14 mm, but increase upon further reduction in thickness from 0.14 mm to 0.04 mm. The grain size was about 140 nm for the AA6061 layer and 235 nm for the AA1050 layer, after the third AR pass.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Fabrication of ultra-thin nanostructured bimetallic foils by Accumulative Roll Bonding and Asymmetric Rolling

Lü

Godbole

et al. 2013

Sci Rep

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“…Our reseach group has measured the evolution of E with cold working for a range of iron-based materials and deformation mode: cold-rolled pure iron (Armco), [17] stainless steel UNS S30400 deformed by drawing in a tensile test, [18] and low-carbon steel deformed by cold drawing. [19] All of them presented a diminution of E with plastic deformation.…”

Section: Introductionmentioning

confidence: 99%

Change of Young’s modulus of cold-deformed pure iron in a tensile test

Benito

Jorba

Manero

et al. 2005

Metall Mater Trans A

115

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Changes in Young's modulus E (determined according to ASTM E-111) of polycrystalline pure iron deformed by a tensile test at room temperature are determined. From its original mean value, 210 GPa, E decreased with deformation to a mean value of 196 GPa at ϭ 0.060. Thereafter, slight recovery occurred and E stabilized to 198 GPa until the appearance of neck ( ϭ 0.100). With the aim to examine the causes of this behavior, residual stresses and textures were measured and the dislocation structure was observed by transmission electron microscopy (TEM). Longitudinal residual stresses increased from the first step of deformation ( ϭ 0.015) and remained constant until the samples fractured. There was no significant difference in texture throughout the deformation process, during which the increment of ␣ fiber was smooth. Thus, the decrease of E cannot be attributed to residual stresses or textures. A relationship between dislocation arrangement and decrease of E is proposed. Following the model established by Mott, dislocations can bow out in their glide planes, giving extra elastic strain and thus a decrease of E. The increase of the dislocation density during the first steps of deformation lowers the E values, since the extra elastic strain increases. At higher strains, when the cellular dislocation structure has formed (between ϭ 0.060 and 0.080), the dislocations in cell interiors are capable of giving an extra elastic strain, whereas the dislocations trapped in the cell walls are not. However, the dislocation density in cell interiors is lower than the dislocation density in the early stages of deformation in which the cell structure has not been developed. This produces the slight recovery of E measured at these strains. From ϭ 0.080, the values of E stabilized since no changes in dislocation density in cell interiors are observed.

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“…11,12) Research into the behaviour of Young's modulus during loading with plastic strain has mainly been carried out using the uniaxial tensile test. [13][14][15][16] For some ferrous alloys used in stamping, Young's modulus for loading decreases rapidly with increasing strain and stabilizes after a given amount of strain. An explanation of this phenomenon has been suggested not only for these types of steels, but also for other materials in which this behaviour has been documented.…”

Section: Introductionmentioning

confidence: 99%

Study of the Inelastic Response of TRIP Steels after Plastic Deformation

2005

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A study of the elastic response before and after tensile plastic strain was undertaken for two commercial low-alloyed TRIP steels. These steels, TRIP 700 (C-Mn-Al alloy) and TRIP 800 (C-Mn-Si) are commercial alloys used in sheet metal stamping. The behaviour of the instantaneous tangent modulus (E T ) versus stress during loading and unloading was measured for each degree of prestrain. Loading curves show a decrease in the E T of the deformed samples as compared with the undeformed state. Though at low stresses a highly linear response was measured for both steels, a decrease was obtained for TRIP 700 as strain increased, whereas TRIP 800 remained unchanged. During unloading, a progressive decrease in E T was obtained in all deformed states, with lower chord modulus values as the tensile plastic prestrain increased. The inelastic response observed is attributed mainly to microplastic strain caused by the displacement of mobile dislocations. Thus, the differences between the two TRIP steels studied are related to the microstructure and the different dislocation structures observed in them. A notable consequence of this study is a better accuracy in the prediction of springback passes due to a better understanding of these inelastic effects that stems from going beyond mere use of traditional Young's modulus values.KEY WORDS: TRIP steels; springback; Young's modulus; dislocation structure. This microplastic deformation results firstly from the short range of motion of mobile dislocations, 19) and secondly from the bowing of the dislocation line between pinning points following models proposed by Mott and Friedel,20,21) and by Granato and Lücke. 22) This extra deformation, which occurs below the internal strength level of the material, is recoverable, and is affected by the dislocation density and the total length of dislocation line that is able to move or bow out. Thus, when e mp grows, a decrease in E is expected. The following Eq. (2), proposed by Granato and Lücke,22) summarizes this idea:where b is the magnitude of the Burgers vector, r is the density of the mobile dislocations and x is the average displacement of a dislocation line of length l.As springback appears after tools have been removed, it is the behaviour of Young's modulus 'during unloading' that should be investigated to obtain a more accurate prediction of the recovery from strain after forming. Ghosh et al. 13,23) used uniaxial tensile tests to study strain recovery after plastic prestrain for a type of steel used in sheet metal stamping, and demonstrated the nonlinearity of the unloading part of the stress-strain curve. This "inelastic behaviour" results in an extra deformation that is not predicted by the usual values of Young's modulus, and again is resumed as microplastic strain. This deformation must be accounted for in FEM simulations in order to better predict the final shape of the pieces stamped. The nature of microplastic strain during unloading is mainly associated with the backward movement of the dislocations that pile up during...

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Change of Elastic Constants of Pure Iron Deformed by Cold Rolling

Cited by 5 publications

References 0 publications

Fabrication of ultra-thin nanostructured bimetallic foils by Accumulative Roll Bonding and Asymmetric Rolling

Fabrication of ultra-thin nanostructured bimetallic foils by Accumulative Roll Bonding and Asymmetric Rolling

Change of Young’s modulus of cold-deformed pure iron in a tensile test

Study of the Inelastic Response of TRIP Steels after Plastic Deformation

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