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Dynamic response of magnetic hysteresis, magnetic Barkhausen noise and magneto-acoustic emission in a soft ribbon and electrical steels was studied comprehensively. The measurements were performed under controllable magnetization conditions: sinusoidal/triangular waveforms of the magnetic induction and a triangular waveform of the magnetic field. Magnetizing frequency was varied in a wide range: f mag = 0.5 – 500 and 0.5–100 Hz for the ribbon and the electrical steels, respectively. Magnetization amplitude was fixed on a near-saturation level H max ≃ 100  A/m. Barkhausen noise signal was detected by a sample-wrapping/surface-mounted coil and differently filtered. It was found that intensity of the Barkhausen noise rises approximately as a square root function of the magnetizing frequency. Whereas, level of the magneto-acoustic emission follows the hysteresis loss trend with an additional linear term (classical loss component). [ABSTRACT FROM AUTHOR]

The effect of hot band grain size on the development of crystallographic texture and magnetic properties in non-oriented electrical steel sheet was studied. After cold rolling the samples with different initial grain sizes displayed different microstructures and micro-textures but nearly identical macro-textures. The homogeneous recrystallized microstructure and micro-texture in the sample having small grains caused normal continuous grain growth. The quite irregular microstructure and micro-texture in the recrystallized sample with large initial grain size provided a preferential growth of grains in 〈001〉//ND and 〈113〉//ND which were beneficial for developing superior magnetic properties. [ABSTRACT FROM AUTHOR]

Abstract: Although theoretical models have already been proposed, experimental data is still lacking to quantify the influence of grain size upon coercivity of electrical steels. Some authors consider a linear inverse proportionality, while others suggest a square root inverse proportionality. Results also differ with regard to the slope of the reciprocal of grain size–coercive field relation for a given material. This paper discusses two aspects of the problem: the maximum induction used for determining coercive force and the possible effect of lurking variables such as the grain size distribution breadth and crystallographic texture. Electrical steel sheets containing 0.7% Si, 0.3% Al and 24ppm C were cold-rolled and annealed in order to produce different grain sizes (ranging from 20 to 150μm). Coercive field was measured along the rolling direction and found to depend linearly on reciprocal of grain size with a slope of approximately 0.9(A/m)mm at 1.0T induction. A general relation for coercive field as a function of grain size and maximum induction was established, yielding an average absolute error below 4%. Through measurement of B 50 and image analysis of micrographs, the effects of crystallographic texture and grain size distribution breadth were qualitatively discussed. [Copyright &y& Elsevier]

Abstract: The magnetic properties of nonoriented electrical steels are influenced by the grain size and crystallographic texture. The technologies used to control the grain size in nonoriented electrical steels are approaching their limits. However, there is still some room for improvement of the magnetic properties through texture control. Hot-band annealing is known to be one of the most effective processing stages for texture modification. In this study, two types of initial grain sizes prior to cold rolling are obtained by different hot-band annealing. The effect of initial grain size on texture evolution and magnetic properties in nonoriented electrical steels containing 2% Si is examined. The specimens having different initial grain sizes have significantly different textures in the cold-rolled state and the annealed state. During the recrystallization stage, new grains formed in the coarse-grained specimens have stronger Goss but weaker γ-fibre texture than those in the fine-grained specimens. During the grain growth after complete recrystallization, the coarse-grained specimens still have weaker γ-fibre texture than the fine-grained specimens. The magnetic induction of the coarse-grained specimens is always higher at the same temperature than that of the fine-grained specimens. The core loss of the coarse-grained specimens is lower at the same temperature than that of fine-grained specimens. However, the improvement of the core loss becomes less pronounced as the annealing temperature increases. [Copyright &y& Elsevier]