Method for producing grain oriented silicon steel comprising copper

Claim 1

IN A PROCESS FOR PRODUCING ORIENTED SILICON STEEL INCLUDING THE STEP OF PREPARING A MELT OF STEEL AND CASTING SAME INTO INGOTS, HOT ROLLING SAID INGOTS TO HOT ROLLED BAND GUAGE AN D SUBSEQENTLY COLD ROLLING AND ANNEALING, AS DESIRED TO PRODUCE SILICON STEEL WITH CUBE-ON-EDGE ORIENTATION, THE IMPROVEMENT WHICH COMPRISES PREPARING A MELT OF STEEL HAVING A COMPOSITION CONSISTING ESSENTIALLY OF: CARBON .02 - .07% MANGANESE EQUIVALENT .05 - .24% (%MN + (0.1 TO 0.25) + %CU) SULFUR .01 - .50% SILICON 2.5 - 3.5% ALUMINUM 0.15 - .04% NITROGEN +-90 PARTS PER MILLION COPPER 0.1 TO 0.3% IRON BALANCE AND WHEREIN THE RATIO OF MANGANESE EQUIVALENT TO SULFUR, BY WEIGHT, IS IN THE RANGE OF 2.0 TO 4.75, AND THEREAFTER PROCESSING SAID STEEL TO PRODUCE GRAIN ORIENTED STEEL WITH CUBE-ON-EDGE TEXTURE WHEREBY SAID ORIENTED STEEL HAS A PERMEABILITY OF AT LEAST 1850 AT 10 OERSTEDS DUE TO A DUPLEX SULFIDE AND NITRIDE PRIMARY GRAIN GROWTH INHIBITION SYSTEM, SAID SYSTEM RESULTING FROM THE AFOREMENTIONED CHEMISTRY OF THE STEEL PROCESSED; SAID PROCESSING INCLUDING THE STEP OF SUBJECTING SAID HOT ROLLED BAND TO A TEMPERATURE ABOVE 1400*F FOR 10 SECONDS TO 30 MINUTES, SAID HOT ROLLED BAND HEAT TREATMENT CONTRIBUTING TO THE ATTAINMENT OF SAID HIGH PERMEABILITY FOR SAID ORIENTED SILICON STEEEL