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Leo Kestens - One of the best experts on this subject based on the ideXlab platform.

  • the evolution of cube 001 texture in non oriented electrical steel
    Acta Materialia, 2020
    Co-Authors: Leo Kestens, Mehdi Mehdi, Youliang He, Erik J Hilinski, Afsaneh Edrisy
    Abstract:

    Abstract Due to the alignment of two easy 〈100〉 axes in the sheet plane, the cube orientation ({001} ) is an ideal texture for non-oriented electrical steel sheets used as core lamination for electric motors. However, this magnetically favorable texture was rarely able to be produced using Conventional Rolling and annealing routes in non-oriented electrical steels. In this research, inclined cold Rolling − a simple Rolling scheme to alter the initial texture before cold Rolling − was applied to a 2.8 wt% Si non-oriented electrical steel, in order to intentionally “create” a rotated Goss ({110} ) texture before cold Rolling, which was not commonly observed in hot-rolled electrical steels. Plane-strain compression (Rolling) of the rotated Goss was able to produce cube crystallites within the matrix, at the grain boundaries and within the shear bands of the deformed rotated Goss grains. The cube crystallites within the shear bands had lower stored energy than their surroundings, and served as the initial seeds for nucleation. Upon annealing, the cube crystallites preferentially nucleated from the shear bands and competitively grew out of the surrounding substructure, forming a strong cube texture in the final sheet. The formation of the initial cube crystallites within the shear bands of the deformed microstructure was believed to be necessary for the development of a final cube texture in the annealed electrical steel sheet. Although inclined Rolling may be difficult to be implemented in industrial production, its unique capability to produce uncommon initial texture before cold Rolling provides an interesting technique for the study of texture involution during thermomechanical processing.

  • texture comparison between room temperature rolled and cryogenically rolled pure copper
    Acta Materialia, 2015
    Co-Authors: Linsey Lapeire, Jurij J Sidor, Patricia Verleysen, Kim Verbeken, I De Graeve, Herman Terryn, Leo Kestens
    Abstract:

    Abstract Nowadays, due to their potential for superior mechanical properties, a considerable interest in bulk ultrafine grained metals exists. One of the possible formation methods for this ultrafine grained material is cryogenic Rolling. In this work, the influence of cryogenic Rolling on the texture and the microstructure of pure copper is investigated by electron backscatter diffraction (EBSD), both in the deformed and the annealed state. This is done by comparing cryogenically rolled copper with room temperature rolled copper, rolled to the same thickness reductions. A texture difference between the room temperature rolled and cryogenically rolled copper is seen in the deformed state, although the largest texture difference is observed after annealing. These texture differences are mainly attributed to the presence of shear bands in the microstructure of the cryogenically rolled copper. In order to obtain a better understanding of the influence of shear bands on the texture evolution, the grain orientations inside the shear bands are analyzed both experimentally and numerically by applying the visco plastic self-consistent (VPSC) model. A number of shear band specific orientations, which are not observed in the Conventional Rolling texture of fcc materials, could be identified both in the experimental observations and in the simulations.

  • modeling the crystallographic texture changes in aluminum alloys during recrystallization
    Acta Materialia, 2011
    Co-Authors: Leo Kestens, Roumen Petrov
    Abstract:

    Abstract The evolution of crystallographic texture during recrystallization annealing is affected by the hot and cold Rolling parameters. A 6016 Al alloy with various hot band textures was subjected to Conventional Rolling and short time annealing at elevated temperature. Asymmetric Rolling with differential circumferential velocities of the top and bottom rolls was applied to the aluminum alloy under investigation to modify the hot Rolling texture. The presence of large constituent particles enforces strain heterogeneities during cold Rolling. The influence of particles on the development of recrystallization textures is discussed based on the experimental data and the results of crystal plasticity simulations. A recrystallization model based on nucleation and growth selection is presented. The driving force for nucleation was accounted for by applying continuum mechanics crystal plasticity models, which allow calculation of the stored energy of plastic strain for specific orientations of the polycrystalline aggregate and for the strain mode under consideration. Crystal misorientations of type 〈1 1 1〉 40° were attributed to enhanced mobility during the growth stage of recrystallization.

Michael Ferry - One of the best experts on this subject based on the ideXlab platform.

  • Engineering low intensity planar textures in commercial purity nickel sheets by cross roll bonding
    Materials Letters, 2017
    Co-Authors: Jiaqi Duan, M.z. Quadir, Michael Ferry
    Abstract:

    Abstract Accumulative roll bonding is a severe plastic deformation technique capable of generating nano-scale microstructures in sheet metals. This technique can also be exploited for processing novel sheet products that are not possible through Conventional Rolling. In this investigation, cross Rolling was combined with accumulative roll bonding of commercial purity nickel sheets, for obtaining an overall reduction in intensity of the deformation and recrystallization textures, which has been a long-time objective for obtaining drawable face centred cubic metal sheet. Overall, a significant reduction in the texture intensities were achieved by incorporating cross roll bonding. In particular, the dominance of the cube texture component, which readily forms in heavily cold rolled and annealed high stacking fault energy, face centred cubic metals and alloys, was suppressed by adopting this processing route. Texture-based Schmidt factor calculations points to a significant reduction in planar anisotropy of the cross rolled and annealed sheet, which is an important factor governing the earing propensity of deep drawn cups.

P K Liaw - One of the best experts on this subject based on the ideXlab platform.

  • crystallographic texture evolution of three wrought magnesium alloys during equal channel angular extrusion
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2005
    Co-Authors: S R Agnew, P Mehrotra, T M Lillo, G M Stoica, P K Liaw
    Abstract:

    Abstract Texture strongly impacts the plasticity of metals and the equal channel angular extrusion (ECAE) process has been demonstrated to induce unusual textures and enhance the room temperature ductility of magnesium alloys. This paper documents a wide range of textures that may be generated by ECAE of magnesium alloys. Considered broadly, the ECAE processing of magnesium alloys tends to produce 〈0 0 0 1〉 fiber textures. Unlike Conventional Rolling, which tends to produce 〈0 0 0 1〉 || normal direction textures, the orientation of the 〈0 0 0 1〉 fiber texture (as well as its strength) is strongly affected by alloying additions and processing history. For example, route B-processing of Mg–Al–Zn (AZ) alloys tends to produce textures with 〈0 0 0 1〉 highly inclined (∼55°) from the extrusion axis. This texture appears to promote excellent ductilities along the axis of the ECAE billets. End effects, which influence the distribution of strain and texture, are modeled.

Xinming Zhang - One of the best experts on this subject based on the ideXlab platform.

  • finite element analysis of bending behavior and strain heterogeneity in snake Rolling of aa7050 plates using a hyperbolic sine type constitutive law
    Journal of Materials Processing Technology, 2017
    Co-Authors: Jixiang Yang, Jie Liu, Xinming Zhang
    Abstract:

    Abstract Snake Rolling is a relatively new asymmetric Rolling technique adopting a horizontal roll offset and differential roll speeds. In this study, the deformation behavior in snake Rolling of an AA7050 aluminum alloy has been investigated by finite element (FE) simulations using a hyperbolic sine-type constitutive law. The effects of offset distance, thickness reduction, and speed ratio on bending behavior and through-thickness distribution of plastic strains are examined. The optimal speed ratio to obtain flat plates with a negligible curvature is identified for each combination of offset distance and thickness reduction. Examination of the plastic strains in the flat plates indicates that, compared with Conventional Rolling, snake Rolling increases the magnitude and through-thickness homogeneity of the accumulative equivalent strains, and it improves the through-thickness homogeneity of the strain in Rolling direction and shear strain at an expense of their magnitudes. Despite the potential significant effect of asymmetric distributions of contact shear stresses on bending behavior, no simple correlations can be identified between the characteristics of cross shear region and the magnitude or direction of bending. Experiments are conducted to validate the prediction of bending behavior by the FE simulations.

  • microstructure texture and mechanical properties of aa1060 aluminum plate processed by snake Rolling
    Materials & Design, 2016
    Co-Authors: Nan Qin, Jie Liu, Xinming Zhang
    Abstract:

    Abstract Snake Rolling is a relatively new asymmetrical Rolling technique that employs horizontally-displaced rolls with different peripheral speeds. In this study, an AA1060 aluminum plate has been subjected to single-pass snake Rolling to investigate the effect of asymmetric boundary conditions on bending behavior under different thickness reductions. Microstructure, texture and mechanical properties of a flat plate processed by snake Rolling to a 50% thickness reduction are compared with those in Conventional Rolling. The results indicate that snake Rolling leads to a more uniform through-thickness distribution of shear strain and a more significant texture change than Conventional Rolling. Meanwhile, the differences in the average grain size and in the resulting mechanical properties between the two rolled plates fall within experimental errors. It is concluded that the snake Rolling technique is effective in reducing the plate curvature by adjusting the offset distance and speed ratio of the working rolls. The advantage of snake Rolling in improving mechanical properties is insignificant, at least at the level of thickness reduction examined in this study.

Ori Katz - One of the best experts on this subject based on the ideXlab platform.

  • 100 000 frames per second compressive imaging with a Conventional Rolling shutter camera by random point spread function engineering
    Optics Express, 2020
    Co-Authors: Gil Weinberg, Ori Katz
    Abstract:

    We demonstrate an approach that allows taking videos at very high frame-rates of over 100,000 frames per second by exploiting the fast sampling rate of the standard Rolling-shutter readout mechanism, common to most Conventional sensors, and a compressive-sampling acquisition scheme. Our approach is directly applied to a Conventional imaging system by the simple addition of a diffuser to the pupil plane that randomly encodes the entire field-of-view to each camera row, while maintaining diffraction-limited resolution. A short video is reconstructed from a single camera frame via a compressed-sensing reconstruction algorithm, exploiting the inherent sparsity of the imaged scene.

  • 100 000 frames per second compressive imaging with a Conventional Rolling shutter camera by random point spread function engineering
    arXiv: Image and Video Processing, 2020
    Co-Authors: Gil Weinberg, Ori Katz
    Abstract:

    We demonstrate an approach that allows taking videos at very high-speeds of over 100,000 frames per second (fps) by exploiting the fast sampling rate of the standard Rolling-shutter readout mechanism, common to most Conventional sensors, and a compressive-sampling acquisition scheme. Our approach is directly applied to a Conventional imaging system by the simple addition of a diffuser to the pupil plane, randomly encoding the entire field-of-view to each camera row, while maintaining diffraction-limited resolution. A short video is reconstructed from a single camera frame via a compressed-sensing reconstruction algorithm, exploiting inherent sparsity of the imaged scene.