EFFECTS OF INTERNAL OXIDATION AND NITRIDATION ON THE MAGNETIC-PROPERTIES OF NON-ORIENTED ELECTRICAL STEELS

The quantitative effects of internal oxidation and nitridation on the core loss and a-c permeability of several silicon-aluminum non-oriented electrical steels are described. Zones of internal oxidation have a large and relatively constant effect on the magnetic properties of alloys containing a wide range of silicon concentrations. For 0.64 mm sheet composed of alloys containing 0.5 to 2.5 percent silicon, oxide subscales increase the 1.5 T, 60 Hz core loss from 0.05 to 0.07 W/kg per μm of subscale thickness. Zones of internal nitridation in aluminum-bearing alloys have a different influence depending on the size and distribution of the nitride precipitates. Zones of internal nitridation in which the individual precipitates have linear dimensions from 0.1 to 1 μm increase the 1.5 T, 60 Hz core loss of 0.64 mm sheet by 0.015 to 0.07 W/kg. Subscales composed of coarse nitrides having maximum linear dimensions from 2 to 7 μm do not increase the core loss significantly.