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Texture Evolution of Non-Oriented Electrical Steels during Thermomechanical Processing.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Texture Evolution of Non-Oriented Electrical Steels during Thermomechanical Processing./
Author:	Mehdi, Mehdi.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2019,
Description:	262 p.
Notes:	Source: Dissertations Abstracts International, Volume: 80-09, Section: B.
Contained By:	Dissertations Abstracts International80-09B.
Subject:	Mechanical engineering. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=13805926
ISBN:	9780438960978

Texture Evolution of Non-Oriented Electrical Steels during Thermomechanical Processing.
Mehdi, Mehdi.

Texture Evolution of Non-Oriented Electrical Steels during Thermomechanical Processing. - Ann Arbor : ProQuest Dissertations & Theses, 2019 - 262 p.

Source: Dissertations Abstracts International, Volume: 80-09, Section: B.

Thesis (Ph.D.)--University of Windsor (Canada), 2019.

This item is not available from ProQuest Dissertations & Theses.

The aim of this research is to improve the magnetic properties of non-oriented electrical steels (NOES) for magnetic cores used in electric motors. This was done by controlling the grain size and the final texture of the electrical steel sheets, such that the magnetically favourable &thetas;-fibre (//ND) components are promoted, while the magnetically unfavourable γ-fibre (//ND) components are suppressed. The origins of the magnetically favourable cube and Goss textures were investigated through all thermomechanical processing stages using electron backscatter diffraction (EBSD) techniques. Three types of Goss regions were found after cold rolling. The first two types were embedded inside deformed {111} grains, while the third type was located at grain boundaries. Similarly, the cube texture was also retained at grain boundaries, as well as inside the shear bands of deformed rotated Goss {110} grains. Partial recrystallization led to the preferential nucleation of the Goss and cube nuclei. The effect of annealing time and grain growth on the texture evolution of NOES was investigated. It was found that by simply changing the annealing time, the texture showed significantly different features, i.e. depending on the annealing time, the Goss ({011}), the &thetas;-fibre (//normal direction, ND) or the γ-fibre (//ND) may dominate the texture. The formation of the various textures during annealing at different times was discussed against the oriented growth theory based on a statistic analysis of the grain boundary misorientation and grain size. In order to improve the final texture in non-oriented electrical steel, an unconventional cold rolling scheme was employed, in which the cold rolling was carried out at an angle (i.e. 30°, 45°, 60°, and 90°) to the hot rolling direction (HRD). It was found that cold rolling at an angle of 60° resulted in substantially improving the crystallographic texture of NOES. Furthermore, the effect of skin pass rolling at various reduction rates from 5–20% on the texture evolution was investigated. Finally, the effect of annealing temperature on the microstructure and texture of 3.2% Si steel was studied. It was found that having coarse grains after hot band annealing combined with high temperature annealing can result in significantly weakened γ-fibre components, and promoting the &thetas;-fibre texture. The magnetic properties were measured using Epstein frame test and magnetic Barkhausen noise analysis (MBN). It was found that the DC core losses and MBNrms decreased with increasing grain size, due to the decrease in pinning sites. On the other hand, AC measurements revealed that the optimized texture and grain size was achieved after annealing at 850 °C for 60 minutes, with AC core losses comparable to those obtained from commercially available grain-oriented electrical steel (GOES) with the same Si content and sheet thickness.

ISBN: 9780438960978Subjects--Topical Terms:

557493
Mechanical engineering.
Subjects--Index Terms:

Core loss

Texture Evolution of Non-Oriented Electrical Steels during Thermomechanical Processing.
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300 $a 262 p.
500 $a Source: Dissertations Abstracts International, Volume: 80-09, Section: B.
500 $a Publisher info.: Dissertation/Thesis.
500 $a Advisor: Edrisy, Afsaneh;He, Youliang.
502 $a Thesis (Ph.D.)--University of Windsor (Canada), 2019.
506 $a This item is not available from ProQuest Dissertations & Theses.
506 $a This item must not be sold to any third party vendors.
520 $a The aim of this research is to improve the magnetic properties of non-oriented electrical steels (NOES) for magnetic cores used in electric motors. This was done by controlling the grain size and the final texture of the electrical steel sheets, such that the magnetically favourable &thetas;-fibre (//ND) components are promoted, while the magnetically unfavourable γ-fibre (//ND) components are suppressed. The origins of the magnetically favourable cube and Goss textures were investigated through all thermomechanical processing stages using electron backscatter diffraction (EBSD) techniques. Three types of Goss regions were found after cold rolling. The first two types were embedded inside deformed {111} grains, while the third type was located at grain boundaries. Similarly, the cube texture was also retained at grain boundaries, as well as inside the shear bands of deformed rotated Goss {110} grains. Partial recrystallization led to the preferential nucleation of the Goss and cube nuclei. The effect of annealing time and grain growth on the texture evolution of NOES was investigated. It was found that by simply changing the annealing time, the texture showed significantly different features, i.e. depending on the annealing time, the Goss ({011}), the &thetas;-fibre (//normal direction, ND) or the γ-fibre (//ND) may dominate the texture. The formation of the various textures during annealing at different times was discussed against the oriented growth theory based on a statistic analysis of the grain boundary misorientation and grain size. In order to improve the final texture in non-oriented electrical steel, an unconventional cold rolling scheme was employed, in which the cold rolling was carried out at an angle (i.e. 30°, 45°, 60°, and 90°) to the hot rolling direction (HRD). It was found that cold rolling at an angle of 60° resulted in substantially improving the crystallographic texture of NOES. Furthermore, the effect of skin pass rolling at various reduction rates from 5–20% on the texture evolution was investigated. Finally, the effect of annealing temperature on the microstructure and texture of 3.2% Si steel was studied. It was found that having coarse grains after hot band annealing combined with high temperature annealing can result in significantly weakened γ-fibre components, and promoting the &thetas;-fibre texture. The magnetic properties were measured using Epstein frame test and magnetic Barkhausen noise analysis (MBN). It was found that the DC core losses and MBNrms decreased with increasing grain size, due to the decrease in pinning sites. On the other hand, AC measurements revealed that the optimized texture and grain size was achieved after annealing at 850 °C for 60 minutes, with AC core losses comparable to those obtained from commercially available grain-oriented electrical steel (GOES) with the same Si content and sheet thickness.
590 $a School code: 0115.
650 4 $a Mechanical engineering. $3 557493
650 4 $a Physics. $3 564049
650 4 $a Materials science. $3 557839
653 $a Core loss
653 $a Crystallography
653 $a Electrical steel
653 $a Electron backscatter diffraction
653 $a Texture
653 $a Thermomechanical processing
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710 2 $a University of Windsor (Canada). $b Engineering Materials. $3 1241292
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793 $a English
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