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Evaluation the Effect of Thermo-Mechanical Parameters on Microstructure and Texture of Electrical Steel for Improving Magnetic Permeability

Ahmadian, Peyman | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 43861 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Akbarzadeh, Abbas
  7. Abstract:
  8. Dependence of some magnetic properties such as core loss and permeability on temper rolling was studied in this thesis. It is shown that with a proper temper rolling sharper textures are obtained in the electrical steel and the magnetic properties in the longitudinal and traverse directions are improved. By texture analysis, it is shown that because of temper rolling, shear strain on the surface of the sheet is the main factor for abnormal grain growth and shear texture formation on the surface. The result of formation of this texture is enhancement of the {100} intensity and reduction of the {111} intensity, leading to the improvement of the permeability. Temper rolling is always accompanied with final annealing for optimizing the microstructure and texture. Degree of temper rolling, surface conditions of the rolls and final annealing conditions are the important factors which control the grain growth and final texture formation. These parameters were investigated and it is observed that with smooth rolls and 5% temper rolling reduction and annealing in a controlled atmosphere of 85 % N2 – 15 % H2 for 1 hour at 850 0C permeability is increased at all three anisotropic directions. Temper rolling with smooth rolls cause to reduce the friction and rolling load. The resulting sharp surface texture, also, increases the magnetic anisotropy. On the other hands, magnetic anisotropy is reduced by using rough rolls. So, the smooth rolls are suitable for transformer applications, whereas the rough rollers provide less anisotropy as needed for general electrical steels in motors and generators
  9. Keywords:
  10. Textures ; Core Loss ; Electric Motors ; Thermomechanical Treatment ; Electrical Steels ; Magnetic Anisotropic ; Final Annealing

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