The effect of γ-ray irradiation on magnetic properties of electromagnetic Fe–Si (97%–3%) sheets

The effect of γ-ray irradiation on magnetic properties of electromagnetic steel sheets has been investigated. The measurements were carried out using transformer Fe–Si (97%–3%) sheets. The energy losses and the dependence of the relative permeability as well as of the differential permeability on the magnetic field strength before and after irradiation were measured. The measurements show that the energy losses in the electromagnetic sheets, for a maximum magnetic induction of 1.0 tesla at the frequency of 50 Hz, decreased to less than 10% after irradiation in comparison with the energy losses before irradiation. Also the value of the saturation magnetic induction decreased by about 10% after irradiation. However, the values of the relative permeability in the region of rotation of magnetization domains after irradiation decreased on the average by 5%, whereas the values of their differential permeability around each working point remained unchanged.