This specification covers the detailed requirements for specified grades of flat-rolled, grain-oriented, fully processed low-carbon silicon-iron electrical steels, whose low core loss and high permeability in the direction of rolling have been achieved by appropriate metallurgical processing. These steels are primarily used in transformer cores operating at moderate to high magnetic flux densities at commercial power frequencies. The ASTM core-loss type designations for the electrical steels covered here are 18G041, 23G045, 27G051, 30G058, 35G066, 23H070, 27H074, 30H083, 35H094, 23P060, 27P066, 23Q054, and 27Q057. Steels may be acquired in any of four conditions, classified according to a combination of material form and surface type or treatment as desired for the expected end use. Materials shall conform to specified values of magnetic properties (core loss, permeability, and magnetic aging), physical dimensions (thickness, length, and width), and mechanical properties (lamination factor and ductility).

1.1 This specification 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 magnetic flux densities 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 3.2 % 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 (1) conventional grain-oriented electrical steel tested at 15 kG (1.5 T) in accordance with Test Method A343/A343M, (2) conventional grain-oriented electrical steel tested at 17 kG (1.7 T) in accordance with Test Method A343/A343M, (3) high-permeability grain-oriented electrical steel tested at 17 kG (1.7 T) in accordance with Test Method A343/A343M, and (4) laser-scribed high-permeability grain-oriented electrical steel tested at 17 kG (1.7 T) in accordance with Test Methods A804/A804M.

1.4 The values stated in customary (cgs-emu and inch-pound) units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units, which are provided for information only and are not considered standard.