Inverse critical strains for jerky flow in Al-Mg alloys

Balı́k, J.; Lukáč, P.; Kubin, L.P.

doi:10.1016/s1359-6462(99)00373-5

Cited by 50 publications

(21 citation statements)

References 13 publications

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“…Also, the same strain rate effect on ε c is observed for the homogenized alloy. It should be mentioned that this inverse dependence of ε c on strain rate has also been reported for some Al 5Mg alloys [32,33]. Fig.…”

Section: 2supporting

confidence: 78%

Serrated flow in powder metallurgy Al–5%Mg–1.2%Cr alloy processed by equal channel angular pressing

Eddahbi

Monge

Muñóz

et al. 2012

Materials Characterization

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Abstract:The microstructure, texture and mechanical behavior of the powder metallurgy Al 5wt.%Mg 1.2 wt.%Cr alloy subjected to equal channel angular pressing (ECAP) has been investigated. The material processed by ECAP, as well as in the homogenized condition, exhibited room temperature serrated flow (SF) up to fracture. The critical stress for the serration onset decreased with increasing strain rate or ECAP temperature. The results indicated that this SF was induced by shear banding. The stress oscillations were attributed to the interaction between shear bands (SBs) and obstacles like second phase particles, and dislocation locks produced by strain hardening. The early stages of the stress strain σ ε curves of the ECAP processed samples showed a transition from type B serrations with continuous strain hardening to type B serrations superimposed on a succession of constant stress plateaus when the tensile strain rate was increased from 10

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Section: 2supporting

confidence: 78%

Serrated flow in powder metallurgy Al–5%Mg–1.2%Cr alloy processed by equal channel angular pressing

Eddahbi

Monge

Muñóz

et al. 2012

Materials Characterization

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“…Each stress drop of a serrated plastic flow that occurs during a constant-strain-rate test corresponds to a macroscopically observable plastic avalanche of one of these localized bands [23,24]. Experimental observations have shown that PLC bands are of different types, and the transition between band types may occur upon changes in strain rate and temperature [25,26].…”

Section: Plc Effectmentioning

confidence: 99%

“…The critical strain, analyzed by a number of tests on substitutional alloys, has an Arrhenius type relationship with the test temperature [128]. An increase in the critical strain with increasing strain rate or with decreasing temperature is referred to as 'normal' behavior, while the opposite can also be observed and is referred to as inverse behavior [26,75,129,130]. While inverse behavior is attributed mostly to inhomogeneity, it also occurs in homogeneous solid solutions.…”

Section: Critical Strainmentioning

confidence: 99%

The Portevin–Le Chatelier effect: a review of experimental findings

Yılmaz¹

2011

Science and Technology of Advanced Materials

236

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The Portevin-Le Chatelier (PLC) effect manifests itself as an unstable plastic flow during tensile tests of some dilute alloys under certain regimes of strain rate and temperature. The plastic strain becomes localized in the form of bands which move along a specimen gauge in various ways as the PLC effect occurs. Because the localization of strain causes degradation of the inherent structural properties and surface quality of materials, understanding the effect is crucial for the effective use of alloys. The characteristic behaviors of localized strain bands and techniques commonly used to study the PLC effect are summarized in this review. A brief overview of experimental findings, the effect of material properties and test parameters on the PLC effect, and some discussion on the mechanisms of the effect are included. Tests for predicting the early failure of structural materials due to embrittlement induced by the PLC effect are also discussed.

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“…Besides the heat treatment condition, the applied strain rate governs a potential PLC effect. Particularly a negative strain rate sensitivity increases the potential of the occurrence of PLC effects [1,2,4,5,15,32,37,38]. In order to characterize the susceptibility of both materials to strain localization, we therefore also performed strain-controlled uniaxial compression tests (Zwick/Roell 20 kN tensile testing machine, Ulm, Germany) at RT with a sudden change of strain rate (jump tests).…”

Section: Introductionmentioning

confidence: 99%

On the PLC Effect in a Particle Reinforced AA2017 Alloy

Härtel¹,

Illgen²,

Frint³

et al. 2018

Metals

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Abstract:The Portevin-Le Châtelier (PLC) effect often results in serrated plastic flow during tensile testing of aluminum alloys. Its magnitude and characteristics are often sensitive to a material's heat treatment condition and to the applied strain rate and deformation temperature. In this study, we analyze the plastic deformation behavior of an age-hardenable Al-Cu alloy (AA2017) and of a particle reinforced AA2017 alloy (10 vol. % SiC) in two different conditions: solid solution annealed (W) and naturally aged (T4). For the W-condition of both materials, pronounced serrated flow is observed, while both T4-conditions do not show distinct serrations. It is also found that a reduction of the testing temperature (−60 • C, −196 • C) shifts the onset of serrations to larger plastic strains and additionally reduces their amplitude. Furthermore, compressive jump tests (with alternating strain rates) at room temperature confirm a negative strain rate sensitivity for the W-condition. The occurring PLC effect, as well as the propagation of the corresponding PLC bands in the W-condition, is finally characterized by digital image correlation (DIC) and by acoustic emission measurements during tensile testing. The formation of PLC bands in the reinforced material is accompanied by distinct stress drops as well as by perceptible acoustic emission, and the experimental results clearly show that only type A PLC bands occur during testing at room temperature (RT).

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Inverse critical strains for jerky flow in Al-Mg alloys

Cited by 50 publications

References 13 publications

Serrated flow in powder metallurgy Al–5%Mg–1.2%Cr alloy processed by equal channel angular pressing

Serrated flow in powder metallurgy Al–5%Mg–1.2%Cr alloy processed by equal channel angular pressing

The Portevin–Le Chatelier effect: a review of experimental findings

On the PLC Effect in a Particle Reinforced AA2017 Alloy

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