Constitutive modeling of strain induced grain boundary migration via coupling crystal plasticity and phase-field methods

Jafari, Meysam; Jamshidian, M.; Ziaei-Rad, Saeed; Raabe, Dierk; Roters, Franz

doi:10.1016/j.ijplas.2017.08.004

Cited by 45 publications

(10 citation statements)

References 49 publications

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“…It has been estimated that the temper rolling introduces a soft deformation into the material, which accounts for 5–10% reduction in its thickness [12,13,14]. Thus, the semi-finished steels possess some extent of stored deformation energy, accumulated in dislocation structures, which can provide a sufficient driving force for a selective grain growth process, also known as strain-induced grain boundary migration phenomenon [15]. It is generally accepted, that the stored deformation energy is proportional to the amount of slip activity, which in polycrystalline materials depends on grain orientation plane, according to the sequence E {1 1 1} > E {1 1 2} > E {1 0 0} [16,17], where {hkl} represents the plane parallel to the rolling plane in Miller indices notations.…”

Section: Introductionmentioning

confidence: 99%

Improving the Magnetic Properties of Non-Oriented Electrical Steels by Secondary Recrystallization Using Dynamic Heating Conditions

et al. 2019

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In the present work, we have used unconventional short-term secondary recrystallization heat treatment employing extraordinary high heating rate to develop coarse-grained microstructure with enhanced intensity of rotating cube texture {100}<011> in semi-finish vacuum degassed non-oriented electrical steels. The soft magnetic properties were improved through the increase of grains size with favourable cube crystallographic orientation. The appropriate final textural state of the treated experimental steels was achieved by strain-induced grain boundary migration mechanism, activated by gradient of accumulated stored deformation energy between neighbouring grains after the application of soft cold work, combined with steep temperature gradient during subsequent heat treatment under dynamic heating conditions. The materials in our experimentally prepared material states were mounted on the stator and rotor segments of electrical motors and examined for their efficiency in real operational conditions. Moreover, conventionally long-term heat treated materials, prepared in industrial conditions, were also tested for reference. The results show that the electrical motor containing the segments treated by our innovative approach, exhibits more than 1.2% higher efficiency, compared to the motor containing conventionally heat treated materials. The obtained efficiency enhancement can be directly related to the improved microstructural and textural characteristics of our unconventionally heat treated materials, specifically the homogenous coarse grained microstructure and the high intensity of cube and Goss crystallographic texture.

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Section: Introductionmentioning

confidence: 99%

Improving the Magnetic Properties of Non-Oriented Electrical Steels by Secondary Recrystallization Using Dynamic Heating Conditions

et al. 2019

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“…These approaches strongly differ from multiphase-field models of GB migration which assign one phase-field variable to each initial grain orientation, thus requiring the introduction of new phase fields at each material point inside a grain to allow for heterogeneous lattice rotation to occur. That is why the recent multiphase-field models [38,77] rely on a Taylor assumption for the proposed coupling between phase field and crystal plasticity.…”

Section: Introductionmentioning

confidence: 99%

A Cosserat–phase-field theory of crystal plasticity and grain boundary migration at finite deformation

Ask

Forest

Appolaire

et al. 2018

Continuum Mech. Thermodyn.

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In metallic polycrystals, an important descriptor of the underlying microstructure is the orientation of the crystal lattice of each grain. During thermomechanical processing, the microstructure can be significantly altered through deformation, nucleation of new subgrains and grain boundary migration. Cosserat crystal plasticity provides orientation as a degree of freedom and is therefore a natural choice for the development of a coupled framework to deal with concurrent viscoplasticity and grain growth. In order to take into account grain boundary motion, the Cosserat theory is adapted with inspiration from orientation phase-field models. This allows for the microstructure at a material point to evolve on the one hand due to deformation-induced lattice reorientation and on the other hand due to a sweeping grain boundary. With a proper separation of plastic evolution in the bulk of the grain and in the grain boundary, the model can successfully capture grain boundary migration due to lattice curvature and due to statistically stored dislocations.Keywords Cosserat crystal plasticity · Phase-field method · Grain boundary migration Communicated by Francesco dell'Isola.A. Ask · S. Forest (B) · K. Ammar MINES ParisTech,

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“…However, in contrast to semi-finished steel, which is characterized by pronounced microstructural evolution, the microstructure of fully finished steel does not exhibit any significant changes after the heat treatment (see Figure 3b). This observation can be easily explained by the fact that fully finished steel does not possess the necessary storage deformation energy, which represents the main driving force for strain-induced grain boundary migration (SIBM) [33]. In our previous works [26,27], it has been shown that pronounced selective grain growth could be achieved in temper-rolled NO steel subjected to small plastic deformation (about 2%–6%) and subsequent dynamic heat treatment using a very high heating rate.…”

Section: Resultsmentioning

confidence: 99%

“…The evaluation of texture components of investigated fully finished steel clearly shows that the plastic deformation induced by mechanical bending in combination with dynamic annealing have a very positive effect on the development of desired microstructure exhibiting coarse grains with rotated cube crystallographic orientation. A small deformation gradient through the sheet cross-section achieved by bending rolling and detected by our nano-indentation measurements (Figure 2), provides the necessary stored deformation energy, serving as primary driving force for the selective grain migration [33].…”

Section: Resultsmentioning

confidence: 99%

Evolution of Power Losses in Bending Rolled Fully Finished NO Electrical Steel Treated under Unconventional Annealing Conditions

et al. 2019

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Currently, the non-oriented (NO) iron-silicon steels are extensively used as the core materials in various electrical devises due to excellent combination of their mechanical and soft magnetic properties. The present study introduces a fairly innovative technological approach applicable for fully finished NO electrical steel before punching the laminations. It is based on specific mechanical processing by bending and rolling in combination with subsequent annealing under dynamic heating conditions. It has been revealed that the proposed unconventional treatment clearly led to effective improvement of the steel magnetic properties thanks to its beneficial effects involving additional grain growth with appropriate crystallographic orientation and residual stress relief. The philosophy of the proposed processing was based on employing the phenomena of selective grain growth by strain-induced grain boundary migration and a steep temperature gradient through the cross-section of heat treated specimens at dynamic heating conditions. The stored deformation energy necessary for the grain growth was provided by plastic deformation induced within the studied specimens during the bending and rolling process. The magnetic measurements clearly show that the specimens treated according to our approach exhibited more than 17% decrease in watt losses in comparison with the specimens treated by conventional heat treatment leading only to stress relief without additional grain growth.

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Constitutive modeling of strain induced grain boundary migration via coupling crystal plasticity and phase-field methods

Cited by 45 publications

References 49 publications

Improving the Magnetic Properties of Non-Oriented Electrical Steels by Secondary Recrystallization Using Dynamic Heating Conditions

Improving the Magnetic Properties of Non-Oriented Electrical Steels by Secondary Recrystallization Using Dynamic Heating Conditions

A Cosserat–phase-field theory of crystal plasticity and grain boundary migration at finite deformation

Evolution of Power Losses in Bending Rolled Fully Finished NO Electrical Steel Treated under Unconventional Annealing Conditions

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