Texture, Microstructure and Properties of Electrical Steels

A special issue of Metals (ISSN 2075-4701).

Deadline for manuscript submissions: closed (15 November 2023) | Viewed by 13210

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CanmetMATERIALS, Natural Resources Canada, Hamilton, ON L8P 0A5, Canada
Interests: electrical steels; crystallographic texture; phase transformations
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Dear Colleagues,

Electrical steels, also known as silicon steels or lamination steels, are indispensable soft magnetic materials widely used in transformers, motors, generators, etc., to confine and amplify the magnetic field and increase the energy efficiency of these devices. Electrical steels may contain up to 6.5 wt% of silicon, and are usually manufactured as very thin sheets in order to reduce eddy current loss. Although in the past decades, alternative soft magnetic materials, e.g., amorphous steel, nanomaterials, and soft magnetic composites, have been developed and commercialized, electrical steels are still the backbone of most electrical applications, because of their low cost, high permeability, relatively high energy efficiency, and excellent mechanical properties. The increasing awareness of climate change and the mitigating strategies, e.g., electrification, taken by governments to reduce greenhouse gas emissions provide a huge opportunity for electrical steels, as the generation, transmission/distribution, and final use of electricity all need electrical steels. The accelerated adoption of electric vehicles in the transportation sector has further increased the demand on electrical steels.

The magnetic properties of electrical steel, especially core loss and magnetic permeability, are not only dependent on the amount of silicon in the alloy and the purity of the steel, but they are also closely related to the texture and microstructure of the steel after thermomechanical processing. Improving the magnetic properties through texture and microstructure control during electrical steel manufacturing has been the subject of much research, and it will continue to be the focus in the future. This Special Issue assembles recent research works on the texture, microstructure, and processing of electrical steels and their effects on the final magnetic properties. Reviews, new processing technologies to manufacture electrical steels, and new methods to characterize the texture, microstructure, and magnetic properties are also welcomed.

Dr. Youliang He
Guest Editor

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Keywords

  • electrical steels
  • crystallographic texture
  • microstructure
  • magnetic properties
  • thermomechanical processing
  • recrystallization
  • rolling
  • electron backscatter diffraction
  • X-ray diffraction

Published Papers (6 papers)

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Research

11 pages, 2805 KiB  
Article
Gradient Recrystallization Behavior of a Moderate Warm-Rolled Non-Oriented Fe-6.5wt%Si Alloy
by Haijie Xu, Cheng Xu, Lulan Jiang, Yuanxiang Zhang, Xuedao Shu and Xiaogang Lin
Metals 2023, 13(2), 370; https://doi.org/10.3390/met13020370 - 12 Feb 2023
Viewed by 1171
Abstract
In Fe-Si alloy systems, the Fe-6.5wt%Si alloy shows low iron core losses and near-zero magnetostriction, thus having great potential for high-frequency applications. In this study, an Fe-6.5wt%Si alloy hot band was subjected to a moderate warm rolling with a thickness reduction of 40%, [...] Read more.
In Fe-Si alloy systems, the Fe-6.5wt%Si alloy shows low iron core losses and near-zero magnetostriction, thus having great potential for high-frequency applications. In this study, an Fe-6.5wt%Si alloy hot band was subjected to a moderate warm rolling with a thickness reduction of 40%, and then annealed at different temperatures. The recrystallization behavior was investigated using the EBSD technique. After the moderate warm rolling, the initial gradient structure of the hot band is inherited, leading to gradient recrystallization behaviors during the further annealing process. The sheet surface first densely nucleates and forms strong <110>//ND and {221}<114> textures. However, the <110>//ND and {221}<114> grains have fewer high-mobility and high-energy (20–45°) boundaries than the other oriented matrix grains, leading to insufficient growth advantages. In the center region, the recrystallization is slow, but the nuclei usually have larger sizes. The inheritance of the <001>//ND (θ-fiber) texture from the initial hot band appears. Some θ-fiber grains, which have easy-magnetized <001> axes lying in the sheet plane, preferentially nucleate in the strong α-fiber textured matrices and form a strong θ-fiber recrystallization texture in the center region. Full article
(This article belongs to the Special Issue Texture, Microstructure and Properties of Electrical Steels)
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18 pages, 14253 KiB  
Article
Effect of Secondary Cold Rolling Reduction Rate on Secondary Recrystallization Behavior of CGO Steel
by Lifeng Fan, Zhiyu Guo, Erbin Yue and Jianzhong He
Metals 2023, 13(2), 289; https://doi.org/10.3390/met13020289 - 31 Jan 2023
Viewed by 1082
Abstract
With the implementation of the “double carbon” policy in various countries in the world, the demand for grain-oriented electrical steel with low iron loss and high magnetic induction is increasing. Reducing the thickness of the steel sheets is an effective method to reduce [...] Read more.
With the implementation of the “double carbon” policy in various countries in the world, the demand for grain-oriented electrical steel with low iron loss and high magnetic induction is increasing. Reducing the thickness of the steel sheets is an effective method to reduce the iron loss.The sheet thickness reduction means the increasing cold rolling reduction rate, especially the secondary cold rolling reduction rate, will directly affect the texture evolution of the secondary recrystallization process. In this paper, the secondary cold rolling reduction rate of commercial grain-oriented silicon steel was studied by means of X-Ray Diffraction, Electron Backscatter Diffraction. The results showed that Ultra-thin oriented silicon steel cannot be obtained by increasing the secondary cold rolling reduction rate alone; the optimum secondary cold rolling reduction rate was 59.2%. The grain size increased as the secondary cold rolling reduction rate increased and favorable texture content decreased, which was disadvantage to obtain a secondary recrystallization environment. Full article
(This article belongs to the Special Issue Texture, Microstructure and Properties of Electrical Steels)
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15 pages, 17125 KiB  
Article
Microstructure Evolution in a GOES Thin Strip
by Anastasia Volodarskaja, Kryštof Hradečný, Renáta Palupčíková, Petra Váňová and Vlastimil Vodárek
Metals 2023, 13(1), 51; https://doi.org/10.3390/met13010051 - 24 Dec 2022
Viewed by 1054
Abstract
This paper focuses on the evolution of the microstructure in a grain-oriented electrical steel (GOES) thin strip after casting. After solidification, the microstructure consisted of delta-ferrite. A small fraction of austenite was formed during the cooling of the thin strip in the two-phase [...] Read more.
This paper focuses on the evolution of the microstructure in a grain-oriented electrical steel (GOES) thin strip after casting. After solidification, the microstructure consisted of delta-ferrite. A small fraction of austenite was formed during the cooling of the thin strip in the two-phase region (gamma+delta). Fine Cr2CuS4 particles precipitated in the ferrite and along the delta/gamma interfaces. Laths of primary Widmanstätten austenite (WA) nucleated directly on the high-angle delta-ferrite grain boundaries. The formation of WA laths in both adjacent ferritic grains resulted in a zig-zag shape of delta-ferrite grain boundaries due to their local rotation during austenite nucleation. Based on the EBSD results, a mechanism of the formation of the zig-zag grain boundaries has been proposed. Besides the Widmanstätten morphology, austenite also formed as films along the delta-ferrite grain boundaries. Sulfide precipitation along the delta/gamma interfaces made it possible to prove that austenite decomposition upon a drop in temperature was initiated by the formation of epitaxial ferrite. Further cooling brought the decay of austenite to either pearlite or a mixture of plate martensite and some retained austenite. Full article
(This article belongs to the Special Issue Texture, Microstructure and Properties of Electrical Steels)
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15 pages, 7246 KiB  
Article
Role of Hot Rolling in Microstructure and Texture Development of Strip Cast Non-Oriented Electrical Steel
by Haitao Jiao, Xinxiang Xie, Xinyi Hu, Longzhi Zhao, Raja Devesh Kuma Misra, Dejia Liu, Yanchuan Tang and Yong Hu
Metals 2022, 12(2), 354; https://doi.org/10.3390/met12020354 - 18 Feb 2022
Cited by 4 | Viewed by 2957
Abstract
In this study, the effect of the hot-cold rolling process on the evolution of the microstructure, texture and magnetic properties of strip-cast non-oriented electrical steel was investigated by introducing hot rolling with different reductions. The results indicate that hot rolling with an appropriate [...] Read more.
In this study, the effect of the hot-cold rolling process on the evolution of the microstructure, texture and magnetic properties of strip-cast non-oriented electrical steel was investigated by introducing hot rolling with different reductions. The results indicate that hot rolling with an appropriate reduction, such as the 20% used in this study, increases the shear bands and {100} deformed microstructure in the cold roll sheet. As a result, in our study, enhanced η and Cube recrystallization texture and the improved magnetic induction were obtained. However, hot rolling with excessive reduction (36–52%) decreased the shear bands and increased the α-oriented deformation microstructure with low stored energy. It enhanced the α recrystallization texture and weakened the η texture, resulting in a decrease in the magnetic induction. In addition, hot rolling promoted the precipitation of supersaturated solid solution elements in the as-cast strip, thereby affecting the subsequent microstructure evolution and the optimization of its magnetic properties. Full article
(This article belongs to the Special Issue Texture, Microstructure and Properties of Electrical Steels)
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12 pages, 6098 KiB  
Article
Optimum Magnetic Properties of Non-Oriented Electrical Steel Produced by Compact Strip Production Process
by Junqiang Cong, Feihu Guo, Jialong Qiao, Shengtao Qiu and Haijun Wang
Metals 2022, 12(1), 64; https://doi.org/10.3390/met12010064 - 28 Dec 2021
Cited by 5 | Viewed by 2313
Abstract
Optimum grain size and effects of crystallographic textures on magnetic properties of Fe-0.65%Si non-oriented electrical steel produced by compact strip production (CSP) process were investigated by optical microscope, electron backscatter diffraction (EBSD), and X-ray diffraction (XRD) techniques. Magnetic induction and core loss show [...] Read more.
Optimum grain size and effects of crystallographic textures on magnetic properties of Fe-0.65%Si non-oriented electrical steel produced by compact strip production (CSP) process were investigated by optical microscope, electron backscatter diffraction (EBSD), and X-ray diffraction (XRD) techniques. Magnetic induction and core loss show a decreasing trend with the increase of grain size, and grain sizes for optimal magnetic properties are in the range of 26–30 μm. Core loss would be mainly affected by grain size, whereas crystallographic texture would primarily affect magnetic flux density. Magnetic properties increase with increasing of texture factor (volume fraction ratio of {100}/{111}) and magnetic texture factor (volume fraction ratio of <100>/<111>), and increasing with the decrease of A-parameter (minimum angle between magnetization direction and the closest <100> direction) and A(h), respectively. Simultaneously, with increasing of A-parameter and A(h), a linear decrease of B50 was obtained. Full article
(This article belongs to the Special Issue Texture, Microstructure and Properties of Electrical Steels)
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20 pages, 11219 KiB  
Article
Textures of Non-Oriented Electrical Steel Sheets Produced by Skew Cold Rolling and Annealing
by Youliang He and Erik J. Hilinski
Metals 2022, 12(1), 17; https://doi.org/10.3390/met12010017 - 22 Dec 2021
Cited by 10 | Viewed by 2954
Abstract
In order to investigate the effect of cold rolling deformation mode and initial texture on the final textures of non-oriented electrical steels, a special rolling technique, i.e., skew rolling, was utilized to cold reduce steels. This not only altered initial textures but also [...] Read more.
In order to investigate the effect of cold rolling deformation mode and initial texture on the final textures of non-oriented electrical steels, a special rolling technique, i.e., skew rolling, was utilized to cold reduce steels. This not only altered initial textures but also changed the rolling deformation mode from plane-strain compression (2D) to a more complicated 3D mode consisting of thickness reduction, strip elongation, strip width spread and bending. This 3D deformation induced significantly different cold-rolling textures from those observed with conventional rolling, especially for steels containing low (0.88 wt%) and medium (1.83 wt%) amounts of silicon at high skew angles (30° and 45°). The difference in cold-rolling texture was attributed to the change of initial texture and the high shear strain resulting from skew rolling. After annealing, significantly different recrystallization textures also formed, which did not show continuous <110>//RD (rolling direction) and <111>//ND (normal direction) fibers as commonly observed in conventionally rolled and annealed steels. At some skew angles (e.g., 15–30°), the desired <001>//ND texture was largely enhanced, while at other angles (e.g., 45°), this fiber was essentially unchanged. The formation mechanisms of the cold rolling and recrystallization textures were qualitatively discussed. Full article
(This article belongs to the Special Issue Texture, Microstructure and Properties of Electrical Steels)
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