Identification of a strain-aging model accounting for Lüders behavior in a C-Mn steel

Marais, A.; Mazière, Matthieu; Forest, Samuel; Parrot, A.; Delliou, Patrick Le

doi:10.1080/14786435.2012.699687

Cited by 31 publications

(19 citation statements)

References 34 publications

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“…The Lüders behavior is modelled as a simplified horizontal Lüders plateau in the plastic stress-strain curve. There are many proposals for more realistic modelling of the Lüders instability in literature, which for instance include strain drops or strain softening [8,17,19,20,[28][29][30][31], but the simplified flat Lüders plateau is assumed to give a sufficient approximation to the material behavior in the present analysis. This is verified by doing analyses using a material model similar to the model in [20].…”

Section: Materials Model and Numerical Proceduresmentioning

confidence: 99%

“…These instabilities are associated with unpinning of dislocations from nitrogen and carbon atmospheres and dislocation multiplication, and they result in macroscopic inhomogeneous deformation [8,[15][16][17][18][19][20]. The Lüders instability is in uniaxial tensile tests observed as nearly horizontal stress plateaus, called Lüders plateaus, in the stress-strain curves after reaching the elastic limit of the material.…”

Section: Introductionmentioning

confidence: 99%

“…The most obvious temperature dependent parameter is the yield strength, which for most steels increase with decreasing temperature [2][3][4][5][6][7][8][9][10][11][12][13][14]. Another temperature dependent property is the ductile-to-brittle transition (DBT) in steels.…”

Section: Introductionmentioning

confidence: 99%

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Effect of low temperature tensile properties on crack driving force for Arctic applications

Dahl

Ren

Akselsen

et al. 2018

Theoretical and Applied Fracture Mechanics

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Many petroleum companies expand their activities further north towards the Arctic region, resulting in design temperatures down to −60• C, which is much lower than what is usual for most current petroleum installations. As properties of steels are temperature dependent, it is of great interest to evaluate the effects of low temperature on the crack driving force in steels. The present work investigates these effects numerically using finite element (FE) models of single-edge-notchedtension (SENT) specimens with crack depths 0.1 ≤ a/W ≤ 0.5. The effects of Lüders strain, yield strength and crack depth on the crack tip opening displacement (CTOD) and the relation between CTOD and crack mouth opening displacement (CMOD) are studied, and it is shown that an increase in yield strength and Lüders strain, as a result of Arctic temperature, intensifies the crack driving force. It is also shown that the crack depth has very little influence on the effect of Lüders strain on the CTOD. An approximate model that can be used to estimate the CTOD based on yield strength, Lüders strain and loading is proposed for gross stress levels σ G /σ y ≤ 0.5 and a crack depth a/W = 0.5. It is finally shown that the tensile properties have a more significant effect on the CTOD-CMOD relation than the crack depth for a SENT specimen.Mange petroleumsselskaper utvider sine aktiviteter nordover mot arktiske områder. Dette fører til designtemperaturer ned til −60• C, noe som er mye lavere enn det som er vanlig for de fleste nåvaerende petroleumsinstallasjoner. Ettersom egenskapene til stål er temperaturavhengige, er det av stor interesseå evaluere effektene av lav temperatur på den drivende kraften for sprekkvekst i stål. Dette arbeidet undersøker disse effektene numerisk ved hjelp av elementmetoden med modeller av single-edge-notched-tension (SENT)-bruddprøver med sprekkdybder 0.1 ≤ a/W ≤ 0.5. Effektene av Lüders tøyning, flytespenning og sprekkdybde på sprekkspissutvidelsen (CTOD) og sammenhengen mellom CTOD og sprekkmunningsutvidelsen (CMOD) er studert, og det er påvist at økt flytespenning og Lüders tøyning, som et resultat av arktisk temperatur, fører til økt drivende kraft for sprekkvekst. Det er også vist at sprekkdybden har liten innflytelse på effekten av Lüders tøyning på CTOD. Det er foreslått en omtrentelig modell som kan bli brukt tilå estimere CTOD basert på flytespenning, Lüders tøyning og last for bruttospenningsnivåer σ G /σ y ≤ 0.5 og sprekkdybde a/W = 0.5. Det er til slutt påvist at materialets strekkegenskaper har en større virkning på CTOD-CMOD-forholdet enn sprekkdybden for en SENT-prøve.i ii PrefaceThe work presented here is a Master's thesis written at Department of Engineering Design and Materials at Norwegian University of Science and Technology (NTNU). The thesis work is carried out as a part of SMACC (Studies of materials behavior for future cold climate applications), which is a research project with several industry partners, and with SINTEF and NTNU as research partners.The author wishes to thank SINTEF fo...

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Section: Materials Model and Numerical Proceduresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of low temperature tensile properties on crack driving force for Arctic applications

Dahl

Ren

Akselsen

et al. 2018

Theoretical and Applied Fracture Mechanics

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“…Static strain aging is modeled by the negative potential Q 2 . The third function ðQ 3 ;b 3 Þ is added to the initial model to smooth out the peak stress for better convergence during finite element simulation (Marais et al, 2012). The corresponding values of the parameters are given in Table 2.…”

Section: Numerical Approach Of the Piobert-lüders Phenomenonmentioning

confidence: 99%

Propagating material instabilities in planar architectured materials

Viard

Dirrenberger

Forest

2020

International Journal of Solids and Structures

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Under tension low carbon steel exhibits inhomogeneous plastic deformation. This instability called Piobert-Lüders banding creates fronts of localized strain that propagate in the structure. To date, Lüders banding has been studied experimentally and numerically only in simple geometries like sheets, tubes and normalized fracture mechanics specimens. This paper focuses on architectured materials and specifically lattice structures which can be defined as a tessellation of unit-cells periodically distributed in space. This class of advanced materials draws new mechanical properties from its inner architecture. We investigate the effect of the architecture on the global behavior of the structure. Especially, how bands interact with the lattice and how to control initiation and propagation of localized strain using the architecture. An elastoplastic material model is used in order to simulate the Piobert-Lüders band formation and propagation. The model also considers a large deformation framework for elastoplasticity with periodic boundary conditions in order to represent the architectured material. Initiation and propagation of material instabilities depend on the geometry as well as its on the relative orientation with respect to the loading direction. Propagating and non-propagating behaviors are identified for the Piobert-Lüders bands and related to the different types of geometry. Material instabilities affect the mechanical behavior of the structure as far as they are governed by the architecture. These conclusions are compared to experimental results from tensile tests on laser-architectured specimens made of ARMCO steel.

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“…In all forthcoming simulations, the mesh is chosen fine enough such that realistic plastic localization bands can develop. However, in a more realistic setup, one should consider strain gradient plasticity or field dislocation mechanics [40] approaches, where a characteristic internal length scale related to width of localization bands can be explicitly or inherently introduced to removes any mesh size dependence of the plastic bands [41]. In our simulations, there is no physical size introduced, only the effect of grain morphologies, its distribution and the ratio of lamellar grain thicknesses in our multilayered simulations is important.…”

Section: Numerical Strategymentioning

confidence: 99%

Crystal Plasticity Modeling of the Effects of Crystal Orientation and Grain-to-Grain Interactions on DSA-Induced Strain Localization in Al-Li Alloys

et al. 2019

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We develop a crystal plasticity model to investigate the coupled actions of crystal orientation, grain neighborhood and grain-to-grain elasto-plastic interactions on dynamic strain aging (DSA) and the onset and development of associated plastic strain localization in Al-Li alloys. Considering simple model multilayered microstructures with preferred orientations representative of rolled alloys, the aim is to identify grain orientation couples that can limit dynamic strain aging induced strain localization without compromising the flow stress and strain hardening properties. To this end, a slip system-based formulation of dynamic strain aging is implemented in a crystal plasticity finite element framework. The model validity is first checked with the simulation of a tensile specimen loaded at quasi-static applied strain rate. The introduction of dynamic strain aging allows predicting complex propagation of intense plastic localization bands. We further investigate the influence of crystal orientations on early strain localization in Al-Cu-Li-Mg alloys, by performing simulations representative of the early stage of a Kahn Tear test for single crystals and layered polycrystals. Using experimentally reported crystal orientations for rolled microstructures, the simulation results show that in both single and multilayered crystals, there is a strong influence of dynamic strain aging on localization patterns, as well as a significant orientation dependence. In multilayered crystals, the nature of strain localization can be remarkably modified when stand-alone crystals of a certain orientation are coupled with other orientations: strain localization may intensify or fades away depending on the coupling with neighboring orientations.

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Identification of a strain-aging model accounting for Lüders behavior in a C-Mn steel

Cited by 31 publications

References 34 publications

Effect of low temperature tensile properties on crack driving force for Arctic applications

Effect of low temperature tensile properties on crack driving force for Arctic applications

Propagating material instabilities in planar architectured materials

Crystal Plasticity Modeling of the Effects of Crystal Orientation and Grain-to-Grain Interactions on DSA-Induced Strain Localization in Al-Li Alloys

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