Modeling bending of α-titanium with embedded polycrystal plasticity in implicit finite elements

Knežević, Marko; Lebensohn, Ricardo A.; Cazacu, Oana; Revil-Baudard, Benoît; Proust, Gwénaëlle; Vogel, Sven C.; Nixon, Michael E.

doi:10.1016/j.msea.2012.11.037

Cited by 161 publications

(53 citation statements)

References 33 publications

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“…2 shows orientation maps based on the electron backscattered diffraction (EBSD) of a deformed microstructure of cast U at a strain of 0.05. In slight contrast to the typical EBSD image of deformed Mg alloys [5], Zr [57], or Ti [39], we observe a large number of relatively thin twin lamellae per grain in cast U. The origin of this unusual twin morphology has yet to be understood.…”

Section: Deformation Mechanisms Of Uraniumcontrasting

confidence: 86%

“…At the same time, they consider the reorientation effect in one of several ways, either via: (i) the predominant twin reorientation (PTR) method [38], (ii) the volume fraction transfer (VFT) scheme [12], (iii) the total Lagrangian approach [17,30], or (iv) the composite grain (CG) method [11]. While successful in capturing the macroscopic stress-strain response and bulk texture evolution [39,40], these schemes do not capture the dynamic and spatially heterogeneous nature of twinning. A particularly important limitation is their inability to account for the resolved shear stress at the twin-parent grain interface responsible for thickening of an existing twin.…”

Section: Introductionmentioning

confidence: 99%

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Explicit incorporation of deformation twins into crystal plasticity finite element models

Ardeljan

McCabe

Beyerlein

et al. 2015

Computer Methods in Applied Mechanics and Engineering

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143

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Highlights• Morphology and crystallography of deformation twinning are implemented in crystal plasticity finite element models.• Intrinsic twinning transformation shear strain is enforced to correspond to the plastic strain accommodated by the twin lamella.• Heterogeneities in spatial mechanical fields are correlated with microstructural changes during twin formation and thickening.• Multiple thin twin lamellae are predicted to be more favorable than a single thick twin lamella in uranium. AbstractDeformation twinning is a subgrain mechanism that strongly influences the mechanical response and microstructural evolution of metals especially those with low symmetry crystal structure. In this work, we present an approach to modeling the morphological and crystallographic reorientation associated with the formation and thickening of a twin lamella within a crystal plasticity finite element (CPFE) framework. The CPFE model is modified for the first time to include the shear transformation strain associated with deformation twinning. Using this model, we study the stress-strain fields and relative activities of the active deformation modes before and after the formation of a twin and during thickening within the twin, and in the parent grain close to the twin and away from the twin boundaries. These calculations are carried out in cast uranium (U), which has an orthorhombic crystal structure and twins predominantly on the {130} <310> systems under ambient conditions. The results show that the resolved shear stresses on a given twin system on the twin-parent grain interface and in the parent are highly inhomogeneous. We use the calculated mechanical fields to determine whether the twin evolution occurs via thickening of the existing twin lamella or formation of a second twin lamella. The analysis suggests that the driving force for thickening the existing twin lamella is low and that formation of multiple twin lamellae is energetically more favorable. The overall modeling framework and insight into why twins in U tend to be thin are described and discussed in this paper.

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Section: Deformation Mechanisms Of Uraniumcontrasting

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Explicit incorporation of deformation twins into crystal plasticity finite element models

Ardeljan

McCabe

Beyerlein

et al. 2015

Computer Methods in Applied Mechanics and Engineering

Self Cite

143

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“…Such calculations are possible with full-field models based on finite elements [17,72] or Green's functions [73] that consider explicitly the grain structure of the metal [74] but not the mean-field formulation adopted here. Nevertheless, to first order, prior work using mean-field models has demonstrated that assuming that the twins associated with the highest Schmid factor variant can lead to reasonable predictions for twin volume fraction and texture for many low-symmetry metals including Zr [7,23,45,46], Be [47,48], Mg [49,50,75], Ti [6] and U [55,56]. This success likely results because the thicker twins usually correspond to twins with the higher Schmid factor [68,76].…”

Section: Primary Twinningmentioning

confidence: 99%

“…The reoriented twin domain introduces a twin boundary, which interacts with subsequent slip, and, within the reoriented twin domains, secondary slip and/or secondary twinning can occur with continued straining. Taken together, these two basic effects of twinning can significantly contribute to material strain hardening in at least three ways: (i) the hardening/softening due to crystal reorientation, from geometrically softer to harder orientations and vice versa [3][4][5][6], (ii) the HallPetch-like hardening due to grain subdivision [4,[7][8][9], and (iii) the Basinski-type hardening mechanism due to transmutations of dislocations from glissile to sessile [10]. Thus, understanding and predicting the mechanical behavior and microstructure evolution of HCP metals require appropriate models for twinning and de-twinning within polycrystal constitutive models.…”

Section: Introductionmentioning

confidence: 99%

Strain rate and temperature effects on the selection of primary and secondary slip and twinning systems in HCP Zr

et al. 2015

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We investigate the temperature and rate dependence of slip, twinning, and secondary twinning in high-purity hexagonal close packed a-Zr over a wide range of temperatures and strain rates (from 76 K to 673 K and 0.001 s À1 to 4500 s À1 ). To reliably identify the dominant deformation mechanisms for each condition, we employ electron-backscattered diffraction (EBSD), dislocation theory, multi-scale polycrystal constitutive modeling, and a thermally activated dislocation density evolution based hardening law. We demonstrate with direct comparison with measurement that the constitutive model, with a single set of intrinsic material parameters, can predict the underlying texture evolution, primary and secondary slip and twin activity, and twin volume fraction associated with the different loading orientations and applied temperatures and strain rates. We find that the f1 0 1 2gh1 0 1 1i twin is the preferred tension twin, either as a primary or secondary twin depending on the sample orientation, over the broad temperature and strain rate range tested. In contrast, we show that the preferred contraction twin, whether f1 1 2 2gh1 1 2 3i or f1 0 1 1gh1 0 1 2i, is sensitive to temperature but insensitive to strain rate and whether it is a primary or secondary twin. Based on the concomitant changes in the dominant slip mode predicted by the model and revealed by the texture development, we rationalize that the temperature-induced transition in contraction twinning is due to the increased predominance of basal hai slip at high temperatures (>673 K). Last, our analysis implies that all twin modes studied are rate insensitive and so the strong influence of strain rate and temperature on twinning is due to the rate-sensitivity of slip.

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“…Finally, finite element analysis (FEA) was performed to better understand the differences between plastic deformations in the HPT and HPDT processes. While future work will involve microstructural predictive models based on polycrystal plasticity ( Ref 6,[17][18][19][20][21], here we employ the continuum J2 constitutive law.…”

Section: Introductionmentioning

confidence: 99%

High-Pressure Double Torsion as a Severe Plastic Deformation Process: Experimental Procedure and Finite Element Modeling

Jahedi

Knežević

Paydar

2015

J. of Materi Eng and Perform

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In the present study, a severe plastic deformation process of high-pressure torsion (HPT) has been modified. The new process is called high-pressure double torsion (HPDT) as both anvils of the conventional HPT process rotate in opposite directions. We manufactured sets of aluminum and pure copper samples using both the HPT process and the newly developed HPDT process to compare between microstructures and microhardness values. Our investigations showed that the copper samples processed by HPDT exhibited larger gradients in microstructure and higher values of hardness. Subsequently, we carried out a set of finite element simulations in ABAQUS/explicit to better understand the differences between the HPT process and the HPDT process. A comparison of the strain distributions of the HPT and HPDT samples revealed a decreasing trend in strain values as the radius increased at the middle surface of the samples. Analysis of the equivalent stress values revealed that stress values for the HPDT samples were higher than those of the HPT samples. Finally, the comparison of the max principal stress values indicated that in the HPDT sample, the extent of the compressive stresses was larger than those in the HPT sample.

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Modeling bending of α-titanium with embedded polycrystal plasticity in implicit finite elements

Cited by 161 publications

References 33 publications

Explicit incorporation of deformation twins into crystal plasticity finite element models

Explicit incorporation of deformation twins into crystal plasticity finite element models

Strain rate and temperature effects on the selection of primary and secondary slip and twinning systems in HCP Zr

High-Pressure Double Torsion as a Severe Plastic Deformation Process: Experimental Procedure and Finite Element Modeling

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