The effect of aluminium on the magnetic properties of lamination steels

The effects of aluminum content, ranging from 0.022 to 0.32 wt.%, on the magnetic properties, grain size, and texture of continuous-annealing lamination steels is investigated. Isochronal treatment in the temperature range 700-900 degrees C was conducted by a continuous-annealing simulator. With an increase of the aluminum content in steels, the size and distribution of aluminum nitride precipitates in the hot-rolled plate influenced the final grain size of steel sheets after annealing. It was found that the core loss of lamination steels decreased with an increase of the aluminum content after annealing at temperatures exceeding 800 degrees C. The aluminum content in steels decreased the core loss of lamination steels predominantly through increasing the electrical resistivity to reduce the eddy current loss and coarsening grain size to decrease the hysteresis loss. On the other hand, the effect of the aluminum content on the permeability of continuous-annealing lamination steels is uncertain. Permeability, being closely related to the steel texture, decreased with an increase in the annealing temperature.