ELECTRICAL STEELS FOR TRANSFORMERS AND ROTATING MACHINES

The total losses improvement of non-oriented and grain-oriented electrical steels is described on the basis of the effects of Si and Al contents, strip thickness, impurities, grain diameter, texture, stress induced by insulation coating and laser treatment. Non-oriented electrical steels with more isotropic magnetic properties and higher magnetic induction due to the ideal texture {100}<0vw>, reduced thickness, lower contents of impurities in connection with the progress of clean steel producing technology and optimum grain size, are viewed as promising core materials for rotating machines. A guiding principe for developing lower-loss grain-oriented electrical steels is to increase the degree of {110}<100> orientation and the silicon content and to decrease the thickness and the grain size in association with a smoother surface and an artificial domain refining technique. The [100][100] double-oriented texture appears the ideal texture for grain-oriented electrical steels used in stacked transformers.