EFFECT OF LONGITUDINAL TENSILE STRESS ON STATIC AND 60-HZ DOMAIN STRUCTURES OF GRAIN-ORIENTED SILICON STEEL

The Kerr effect was used to observe and photograph domain structures in grain-oriented silicon steel under the influence of longitudinal tensile stresses. In normal, unstressed oriented silicon steel the domain structure is typically a mixture of antiparallel and dagger" or "pine tree" domains. The application of uniform tensile stress converts this mixed structure to a completely antiparallel domain structure and reduces the antiparallel domain-wall spacing. The current work shows that the pure antiparallel structure is developed at stresses on the order of 1000 psi. This correlates well with the magnetic property changes associated with the application of uniform tensile stress. The domain-wall spacing refinement is an inverse function of the stress level up to a stress of ≃6500 psi. Higher stresses produced no further change in the domain structure. High-speed motion pictures (≃5000 frames/sec) revealed that the refined spacing was retained during 60 Hz excitation. This effect also would contribute to improved core losses for oriented silicon steel. © 1969 The American Institute of Physics."