On predicting the extent of magnetic aging in electrical steels

Abstract

Magnetic aging of steels is essentially the result of an increase in coercive force, inhibition of ferrite domain wall movement by precipitated carbide particles being the main cause of this increase. In the present work, the nature of the carbides precipitating in four grades of electrical steels has been looked into. Existing postu-lations have been invoked to predict the tent of coercive force enhancement due to metastable (e) and stable (cementite) carbides which have been observed precipitate in these steels. The model of Drabecki and Wyslocki when applied to the case of metastable carbide predicts its tribution to the coercive force fairly accurately. None of the existing models, however, succeeds in suggesting the extent of the increases accruing from the presence of the stable carbide (cementite) particles. Each of the models takes into account only one or two of the isolated aspects of magnetic interaction between matrix and precipitate. It appears that for cementite, whose veral magnetic charac-teristics are quite different from those of the ferrite matrix, all possible interaction parameters have to be taken into account to determine the actual mechanism.