Investigation of the limits of statistical power loss model for 3.2% SiFe electrical steels. I. Role of hysteresis loss

Loss separation experiments on non-oriented and grain-oriented 3.2 wt.% SiFe electrical steels have been used to study, according to the statistical model proposed by Bertotti, the polarisation dependence of the hysteresis loss (Phys) and the internal coercive field (Vo). Furthermore quasi-static characterisation was performed by means of a newly developed hysterisograph, improved to assure constant speed of polarisation under controlled duration of measuring period. The measured hysteresis loss on N.O.-0.35mm samples has confirmed the previous results i.e. the limits of the applicability of model (up to 1.6T in this case) and that the polarisation dependence of hysteresis can be interpreted by two different power law functions, instead of one. The polarisation dependence of Vo field, derived from excess loss behaviour, resulted to be more complex. In special cases, the analysis of quasi-static virgin magnetising curve by means of thermodynamic representation of magnetising processes confirmed the presence of different magnetising mechanisms. The good correlation between the break-points of virgin magnetising curves and the polarisation dependence of hysteresis Phys and Vo field, furthermore the strong dependence of the investigated parameters on the microstructure of material suggest to use these models to examine the changes of magnetising mechanisms, both dynamic and quasi-static characteristics, under varied conditions of microstructure.