Pure iron will suffer from eddy current loss under alternating current (AC) magnetic field and thus can only operate under direct current (DC) magnetic field. In order to overcome this drawback, a small amount of silicon is added to pure iron to form solid solution so that improve electrical resistivity of the alloy and reduce eddy current loss. Silicon steel, which also referred as electrical steel, is an iron alloy with silicon content between 1.5% and 4.5%. Silicon steel can be also divided to hot-rolled steel and cold-rolled steel on the basis of rolling technology. Besides, it also can be grouped in grain-oriented steel and non grain-oriented steel according to the grain orientation. Electrical steel is usually manufactured in strips less than 2mm thick and then cut to specific shape to make laminations which are stacked together to form the laminated cores of transformers, and stator or rotor of electric motors.
