Finished structure and properties of EI Electromagnetic Silicon Steel

- Mar 06, 2019-

The grain size of EI Electromagnetic Silicon Steel on steel refers to the grain size of the steel sheet after annealing, and is usually expressed by the number of crystal grains per unit area. The grain size is commonly used in engineering to indicate that the grain size is large. It is generally believed that the larger the grain size of the EI electromagnetic silicon steel, the better the magnetic properties. Transformer silicon steel sheet with the same composition and thickness of 0.5mm, the relationship between various grain sizes and iron loss obtained by different process conditions.


It can be seen that as the crystal grains increase, the hysteresis loss decreases and the eddy current loss increases. However, for transformer EI electromagnetic silicon steel, the decrease in hysteresis loss is dominant, and the iron loss decreases as the crystal grain increases. The effect of grain size on the iron loss value of a transformer silicon steel sheet is very complicated.


Production practice shows that carbon is precipitated as a cementite along the grain boundary, and as the grain size increases, the iron loss value also decreases. However, under certain actual production conditions, the crystal grains are too large, and the carbon is less likely to precipitate as carbides along the grain boundary, so that some of the carbon atoms are dissolved in the ferrite by the interstitial solid solution. In this case, the carbon is iron-damped. The influence of the value is dominant, so as the grain size increases, the iron loss value increases.


The thinner the EI electromagnetic silicon steel, the smaller the eddy current loss, and the smaller the total core loss of the silicon steel sheet. Therefore, silicon steel sheets for electricians are often formed into sheets. However, the thickness of the silicon steel sheet cannot be reduced indefinitely. In addition to the high manufacturing cost and complicated process of the thin steel sheet, it is not necessarily advantageous for electromagnetic performance, because the thinner the steel sheet, the larger the coercive force, and the hysteresis loss and core loss are also increased.