1.1 This specification (Note 1) covers the detailed requirements to which the specified grades of flat-rolled, grain-oriented, fully processed electrical steels shall conform. These steels are used primarily in transformer cores operating at moderate to high inductions at commercial power frequencies (50 and 60 Hz).

1.2 These grain-oriented electrical steels are low-carbon, silicon-iron alloys with a silicon content of approximately 3.15% in which low core loss and high permeability in the direction of rolling have been achieved by appropriate metallurgical processing.

1.3 The electrical-steel grades described in this specification include conventional grain-oriented electrical steel tested at 15 kG, conventional grain-oriented electrical steel tested at 17 kG, and high-permeability grain-oriented electrical steel tested at 17 kG.