Method of heat treating silicon steel

Claim 1

IN A METHOD OF PRODUCING ORIENTED SILICON STEEL, THE STEP WHICH COMPRISES COLD ROLLING A HOT-ROLLED SILICON STEEL STRIP OF A THICKNESS OF ABOUT 0.075 TO 0.120 INCH HAVING A COMPOSITION CONSISTING ESSENTIALLY, BY WEIGHT, OF ABOUT 2.2 TO 5.25 PERCENT OF SILICON, 0.001 TO 0.05 PERCENT OF AT LEAST ONE MATERIAL OF THE GROUP CONSISTING OF METAL OXIDES, METAL SULFIDES AND METAL NITRIDES, A MAXIMUM OF ABOUT 0.02 PERCENT OF CARBONS, THE REMAINDER IRON, TO REDUCE SAID STRIP ABOUT 60 TO 80 PERCENT, HEATING SAID COLD ROLLED TRIP AT A RATE OF ABOUT 1600* C. TO 2000* C. PER MINUTE TO A TEMPERATURE OF ABOUT 850* C. TO 1050* C. AND MAINTAINING SAID STRIP AT SAID TEMPERATURE FOR A TIME SUFFICIENT TO EFFECT RECRYSTALLIZATION, COLD ROLLING THE THUS HEATTREATED STRIP TO EFFECT A FURTHER REDUCTION OF ABOUT 50 TO 60 PERCENT, BASED ON THE THEN THICKNESS, AND AGAIN HEATING SAID STRIP AT A RATE OF ABOUT 1600* C. TO 2000* C. PER MINUTE TO A TEMPERATURE OF AT LEAST ABOUT 850* C. AND MAINTAINING SAID TEMPERATURE FOR A PERIOD OF TIME JUST SUFFICIENT TO SOFTEN THE MATERIAL, THEN SUBJECTING THE STRIP TO A HIGH TEMPERATURE ANNEAL FOR A PERIOD FO FROM 1 TO 8 HOURS AT A TEMPERATURE OF FROM 1000* C. TO 1300* C., SAID HIGH TEMPERATURE BEING ATTAINED BY HEATING AT A RATE OF FROM 2*C. TO 15*C. PER MINUTE, EACH OF SAID ANNEALS BEING CODUCTED IN A NON-OXIDIZING ATMOSPHERE AND SUBJECTING THE STRIP TO A DECARBURIZING ANNEAL AT A TEMPERATURE NOT EXCEEDING 800* C. IN WET HYDROGEN, THE ORDER OF PRECEDENCE OF THE HIGH TEMPERATURE FINAL ANNEAL AND THE DECARBURIZATION ANNEAL IMMATERIAL.