Electrical steel

[1] Silicon increases the electrical resistivity of iron by a factor of about 5; this change decreases the induced eddy currents and narrows the hysteresis loop of the material, thus lowering the core loss by about three times compared to conventional steel.

[1][2] However, the grain structure hardens and embrittles the metal; this change adversely affects the workability of the material, especially when rolling.

When alloying, contamination must be kept low, as carbides, sulfides, oxides and nitrides, even in particles as small as one micrometer in diameter, increase hysteresis losses while also decreasing magnetic permeability.

Carbon also causes magnetic aging when it slowly leaves the solid solution and precipitates as carbides, thus resulting in an increase in power loss over time.

It is processed in such a way that the optimal properties are developed in the rolling direction, due to a tight control (proposed by Norman P. Goss) of the crystal orientation relative to the sheet.

It is used when cost is more important than efficiency and for applications where the direction of magnetic flux is not constant, as in electric motors and generators with moving parts.

Since amorphous ribbon can be cast to any specific width under roughly 13 inches and can be sheared with relative ease, it is a suitable material for wound electrical transformer cores.

[15][16][17] The magnetic properties of electrical steel are dependent on heat treatment, as increasing the average crystal size decreases the hysteresis loss.

Excessive bending, incorrect heat treatment, or even rough handling can adversely affect electrical steel's magnetic properties and may also increase noise due to magnetostriction.