Piobert–Lüders plateau and Portevin–Le Chatelier effect in an Al–Mg alloy in simple shear

Coër, J.; Manach, Pierre‐Yves; Laurent, Hervé; Oliveira, M. C.; Menezes, L.F.

doi:10.1016/j.mechrescom.2012.11.008

Cited by 49 publications

(36 citation statements)

References 24 publications

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“…Their main feature is the persistent propagation Another distinct feature of the material processed by ECAP is the Lüders-like plateau [25,34,35] following the elastoplastic transition and superimposed with stress drops (Figure 2b). The formation of the Lüders plateau is well documented for Al-Mg alloys (e.g., [37,38]) and is generally explained by the nucleation and propagation of a deformation band. In contrast to the repetitive PLC bands, the Lüders band propagates once, as a result of unpinning of dislocations from solute atmospheres formed during static aging prior to deformation [34,35].…”

Section: Plc Bands Patternsmentioning

confidence: 91%

Peculiar Spatiotemporal Behavior of Unstable Plastic Flow in an AlMgMnScZr Alloy with Coarse and Ultrafine Grains

Lebyodkin

Lebedkina

Mogucheva

et al. 2017

Metals

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Abstract:The work addresses the effects of nanosize particles and grain refinement on the patterns of stress serrations and kinematics of deformation bands associated with the Portevin-Le Chatelier instability of plastic flow. Ultra-fine-grained microstructure was obtained using equal-channel angular pressing of the initial coarse-grained alloy. Tensile tests were carried out on flat specimens at strain rates in the range from 3 × 10 −5 to 1.4 × 10 −2 s −1 . Using local extensometry techniques, it was found that the presence of nanoscale precipitates promotes quasi-continuous propagation of deformation bands in the entire strain-rate range. The grain refinement leads to a transition to relay-race propagation at high strain rates and static strain localization at low rates. The results are discussed from the viewpoint of competition between various dynamical modes of plastic deformation associated with collective dynamics of dislocations.

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Section: Plc Bands Patternsmentioning

confidence: 91%

Peculiar Spatiotemporal Behavior of Unstable Plastic Flow in an AlMgMnScZr Alloy with Coarse and Ultrafine Grains

Lebyodkin

Lebedkina

Mogucheva

et al. 2017

Metals

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“…6,7 Pattern Formation and Material Instabilities Sometimes, dislocations arrange themselves in patterns that may lead to undesired effects for a material in service. For example, Al-Mg alloys for the automotive industry are prone to the PortevinLe Châ telier effect, 8,9 which generates stretcher lines on the aluminum alloys sheets: under certain regimes of strain rate and temperature, plastic strain becomes localized in the form of bands. In addition to cosmetic problems, this can also lead to structural problems: embrittlement can be increased and fracture toughness decreased, leading to unexpected failure.…”

Section: Radiation Damage 45mentioning

confidence: 99%

The Use of Ultrasound to Measure Dislocation Density

Barra

Espinoza-González

Fernández

et al. 2015

JOM

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Artículo de publicación ISIDislocations are at the heart of the plastic behavior of materials yet they are very difficult to probe experimentally. Lack of a practical nonintrusive measuring tool for, say, dislocation density, seriously hampers modeling efforts, as there is little guidance from data in the form of quantitative measurements, as opposed to visualizations. Dislocation density can be measured using transmission electron microscopy (TEM) and x-ray diffraction (XRD). TEM can directly show the strain field around dislocations, which allows for the counting of the number of dislocations in a micrograph. This procedure is very laborious and local, since samples have to be very small and thin, and is difficult to apply when dislocation densities are high. XRD relies on the broadening of diffraction peaks induced by the loss of crystalline order induced by the dislocations. This broadening can be very small, and finding the dislocation density involves unknown parameters that have to be fitted with the data. Both methods, but especially TEM, are intrusive, in the sense that samples must be especially treated, mechanically and chemically. A nonintrusive method to measure dislocation density would be desirable. This paper reviews recent developments in the theoretical treatment of the interaction of an elastic wave with dislocations that have led to formulae that relate dislocation density to quantities that can be measured with samples of cm size. Experimental results that use resonant ultrasound spectroscopy supporting this assertion are reported, and the outlook for the development of a practical, nonintrusive, method to measure dislocation density is discussed.Fondecyt 113038

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“…They conclude that the distribution of the hoop stress in the cup wall is the main factor influencing the springback mechanism in warm forming condition. In addition to the above-mentioned benefits, the stretcher lines arising in the AA5xxx series (Al-Mg alloys) due to the Portevin-Le Chatelier (PLC) effect vanish at warm temperatures, as highlighted in the experimental study performed by Coër et al [10].…”

Section: Introductionmentioning

confidence: 94%

Numerical analysis of different heating systems for warm sheet metal forming

Martins

Alves

Neto

et al. 2015

Int J Adv Manuf Technol

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The main goal of this study is to present an analysis of different heating methods frequently used in laboratory scale and in the industrial practice to heat blanks at warm temperatures. In this context, the blank can be heated inside the forming tools (internal method) or using a heating system (external method). In order to perform this analysis, a finite element model is firstly validated with the simulation of the direct resistance system used in a Gleeble testing machine. The predicted temperature was compared with the temperature distribution recorded experimentally and a good agreement was found. Afterwards, a finite element model is used to predict the temperature distribution in the blank during the heating process, when using different heating methods. The analysis also includes the evaluation of a cooling phase associated to the transport phase for the external heating methods. The results of this analysis show that neglecting the heating phase and a transport phase could lead to inaccuracies in the simulation of the forming phase.

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Piobert–Lüders plateau and Portevin–Le Chatelier effect in an Al–Mg alloy in simple shear

Cited by 49 publications

References 24 publications

Peculiar Spatiotemporal Behavior of Unstable Plastic Flow in an AlMgMnScZr Alloy with Coarse and Ultrafine Grains

Peculiar Spatiotemporal Behavior of Unstable Plastic Flow in an AlMgMnScZr Alloy with Coarse and Ultrafine Grains

The Use of Ultrasound to Measure Dislocation Density

Numerical analysis of different heating systems for warm sheet metal forming

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