Characteristic of grain structure of transformer steel with 3% Si after secondary recrystallization

Abstract

Anisotropic electromagnetic steels made in the form of strips 0.18–0.5 mm thick are commonly used in the production of transformers and other parts of powerful electric and magnetic circuits. The level of power loss in the operation of these devices depends to a considerable degree on the structure of the electromagnetic steels, specifically, on the grain size and the uniformness of their distribution. In the final form the grain structure in the steels is formed in high-temperature annealing as a result of an anomalous grain growth, which is also known as secondary recrystallization. As distinct from normal growth in which the mean grain size increases gradually and simultaneously in the entire volume, in secondary recrystallization only separate grains grow rapidly to a large size while absorbing the surrounding fine (matrix) grains, whose growth is impeded for this or that reason. The present paper considers the results of statistical analysis of the structure of a steel that contains 3% Si.