Forward and reverse rearrangements of dislocations in tangled walls

Hasegawa, Tadashi; Yakou, Takao; Kocks, U.F.

doi:10.1016/0025-5416(86)90262-4

Cited by 106 publications

(38 citation statements)

References 22 publications

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“…In recent years, several microstructural studies by transmission electron microscopy [1][2][3][4][5][6][7][8][9][10], among others) were carried out in order to understand the anisotropic work-hardening behaviour of polycrystalline metals under strain-path changes at large strains. Most of the previous studies were devoted to a better knowledge of the relations between the microstructure evolution (i.e.…”

Section: Evolution Of the Intragranular Microstructurementioning

confidence: 99%

Modelling of anisotropic work-hardening behaviour of metallic materials subjected to strain-path changes

Bouvier

Alves

Oliveira

et al. 2005

Computational Materials Science

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The present paper aims at reviewing some recent progress in developing advanced constitutive models which are devoted to the description of the anisotropic work-hardening behaviour under strain-path changes at large strains of metallic materials. After reviewing some microscopic and macroscopic experimental evidence, a physically-based phenomenological model using four internal state tensor variables is presented. This model can be simplified into several classical phenomenological models in order to take into account either the isotropic or the kinematic hardening or both. The implementation of the proposed models in the in-house finite element code DD3IMP is briefly recalled. Numerical simulations of the stamping of a curved rail are carried out in order to evaluate the accuracy and the efficiency of the proposed models in modelling the springback.

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Section: Evolution Of the Intragranular Microstructurementioning

confidence: 99%

Modelling of anisotropic work-hardening behaviour of metallic materials subjected to strain-path changes

Bouvier

Alves

Oliveira

et al. 2005

Computational Materials Science

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“…For monotonous loading, both U S and U G can increase strongly while the change in U m is considered to be slow or even infinitesimal [32]. In reverse loading, however, dislocation tangles, cells, and even walls can be dissolved [33,34]. During this process of untanglement and dissolution, the freed dislocations contribute to U m .…”

Section: Dislocation Substructuresmentioning

confidence: 96%

On strain gradients and size-dependent hardening descriptions in crystal plasticity frameworks

2006

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Strain gradient crystal plasticity models have been quite successful in describing size-dependent deformation. Various formulations have been suggested in the literature involving approaches that vary considerably in principle. In this respect it is important to associate certain classes of material models to specific deformation mechanisms and to investigate possible inherent restrictions. To this end, the scaling relation between dislocation substructures and the order (first order, second order) of strain gradients in the corresponding continuum formulation are discussed. Conclusions for isotropic and kinematic hardening on slip system level and their related orders in the strain gradients are drawn.

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“…On the other hand, the Bauschinger effect of materials had been recognized to be caused by mainly the accumulation of long-range internal stress due to pile-up of dislocations around obstacles, which in the steel of interest is the Ferrite -Pearlite interface. In the case where the applied stress is reversed, some of the piled-up reversely mobile dislocations move in the opposite direction [19 -23], and after a certain straining, form the equivalent dislocation structures with that before reverse loading; that is, the same dislocation density [19,20,24,25]. Thus, in addition to plastic strain induced by reversely mobile dislocations at the early stage of reverse loading, subsequent plastic straining up to the same dislocation density as reached previously would presumably not aggravate the material damage for ductile cracking.…”

Section: Proposal Of Effective Damage Conceptmentioning

confidence: 99%

Damage concept for evaluating ductile cracking of steel structure subjected to large-scale cyclic straining

Ohata¹,

Toyoda

2004

Science and Technology of Advanced Materials

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Evaluation of ductile crack initiation in steel welded structures subjected to seismic loading is crucial for structural design or safety assessment to prevent brittle fracture induced by ductile cracking. Observation of ductile crack initiation behavior of round-bar specimens with/without circumferential notches tested in single tension revealed that the main controlling factor for ductile cracking in the employed two-phase steel is not growth of voids induced by large inclusions, but nucleation of micro-voids in a soft phase (Ferrite phase) near the Ferrite -Pearlite interface after large-scale plastic straining. The material damage concept under reverse loading, which correlates the material damage for micro-void nucleation to macro-scale mechanical parameters, was proposed in consideration of two aspects of the Bauschinger effect: (a) a mechanical aspect which influences deformation and stress/strain behaviors in steel structures, (b) a material damage aspect caused by dislocation behavior. A new criterion for ductile cracking of structural members under cyclic loading was proposed on the basis of the proposed effective damage concept and 'two-parameter criterion,' which can be applied to the steel structures under increasing load in a single direction. The validity of the advanced two-parameter criterion was verified by subjecting round-bar specimens to cyclic loading tests along the axial direction and cross-shaped specimens to cyclic 3-point bending tests. Consequently, the advanced two-parameter ductile cracking criterion was found to be a transferable criterion for evaluation of critical loading cycle of structural members from small-scale tensile test results. q

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Forward and reverse rearrangements of dislocations in tangled walls

Cited by 106 publications

References 22 publications

Modelling of anisotropic work-hardening behaviour of metallic materials subjected to strain-path changes

Modelling of anisotropic work-hardening behaviour of metallic materials subjected to strain-path changes

On strain gradients and size-dependent hardening descriptions in crystal plasticity frameworks

Damage concept for evaluating ductile cracking of steel structure subjected to large-scale cyclic straining

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