Domain Structure During Magnetization of Grain-Oriented 3% Si–Fe as a Function of Applied Tensile Stress

Abstract

The longitudinal Kerr effect has been used to observed domain structure during dc and 60-Hz magnetization in conventional (110) [001] grain oriented 3% Si–Fe as a function of applied tensile stress parallel to the rolling direction. The observed domain processes indicate that the source of the Villari reversal in this material is demagnetizing fields occurring at grain boundaries and at the sheet surface. In grains where the [001] tilted out of the sheet surface, demagnetizing fields were produced when 90° flux closure domains were eliminated by applied tensile stress. During magnetization under applied tensile stress, these demagnetizing fields restabilized the original unstressed closure structure. High speed movies of the magnetization process in grains with perfect plane orientation revealed that although the 180° wall spacing was decreased by applied tensile stress the flux became very nonuniform due to the buildup of grain boundary demagnetizing fields and the average 180° wall velocity was not decreased. The observed domain processes explain the magnetic properties previously observed in this material under applied tensile stress, e.g., decreased maximum permeability, the appearance of negative magnetostriction and lack of improvement in core loss at stress levels in excess of 500 psi.

Effect of applied tensile stress on the hysteresis curve and magnetic domain structure of grain-oriented transverse Fe-3%Si steel

“…As a result large demagnetizing fields are generated at those boundaries. In previous studies [5,11,[16][17][18] on strips magnetized in rolling direction it was shown that the reason for non-monotonous hysteresis loop behavior under tension were demagnetizing fields occurring at grain boundaries and at the sheet surface due to the removal of closure domains transverse to the rolling direction. From the hysteresis curves in the present paper (Fig.…”

A Study of Stress – Induced Subtle Magnetic Changes in a Mild Steel using Barkhausen Emission-Aided Analysis Approaches

“…Today, despite extensive and intensive theoretical and experimental investigations, [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24], [25], [26], [27], [28], [29], [30], the applied stressinduced micromagnetic effects in ferromagnetic steels are complex and not yet fully understood. In general, the investigation of stress effects on polycrystalline ferromagnetic materials needs a basic reduction to a formulated set of problems solvable by detailed experimental investigations and/or mathematical analysis concerning the dynamics of domain wall motion.…”

“…In general, the investigation of stress effects on polycrystalline ferromagnetic materials needs a basic reduction to a formulated set of problems solvable by detailed experimental investigations and/or mathematical analysis concerning the dynamics of domain wall motion. As such, the application of stress to material results in a modification of strain state and a corresponding change of its elastic energy, [1], [2], [3], [4], [5], [6], [7], [8], [11], [12], [13], [14], [15] as well as in variations of effective strength levels of domain wall pinning sites, [3], [19]. This is related to the general fact that in ferromagnetic materials, the modification of internal stressstrain results in a change in the free energy and consequent changes in the micromagnetic response of the material, [8], [12], [28].…”

“…In these materials, position magnetostriction implies that for reasons of energy minimization, domain magnetization should be along the cubic crystal axis that is closest to the direction of applied stress. This results in bulk stress anisotropy, where the direction of the easy axis shifts toward the direction of applied tensile stress, a fact which may be identified with the positive magnetostriction in steel materials, [6], [12], [13]. These results have been associated with certain changes in the relative population of active 180 0 to 90 0 domain walls, where the number of basic domains of 180 0 increases at the expense of supplementary ones of the 90 0 domain walls, [3], [8].…”

Application of Co–Ni–P Coating on Grain-Oriented Electrical Steel

“…fforts are being made to produce high performance electrical steels through several methods including better secondary recrystallization methods [1], grain orientation control [2], increasing the electrical resistivity, gauge reduction [3] and understanding the magnetic domain structure [4][5][6][7] Perhaps the greatest gains can be made by employing effective stress coatings [8,9] which can play a dominant role in minimizing losses and magnetostriction. The stress can be applied to the material with the help of coatings.…”