Silicon alloy steel with silicon content of 1.0 ~ 4.5% and carbon content of less than 0.08% is called silicon steel. It has the characteristics of high permeability, low coercivity and large resistivity, so the hysteresis loss and eddy current loss are small. It is mainly used as magnetic material in motors, transformers, electrical appliances and electrical instruments. In order to meet the needs of punching and shearing processing when manufacturing electrical appliances, it is also required to have a certain plasticity. In order to improve the magnetic susceptibility and reduce the hysteresis loss, the harmful impurity content is required to be as low as possible, and the plate shape is required to be flat and the surface quality is good.