Processing of metal

Claim 1

IN THE METHOD OF PRODUCING ELECTRICAL STEEL STRIP FROM SILICON STEEL HAIVNG A SILICON CONTENT OF BETWEEN 0.25% AND 4.5% AND A CARBON CONTENT OF UP OF 0.07% CHARACTERIZED IN THAT A CONTINUOUS HEAT TREATMENT OPERATION UTILIZING A SINGLE ATMOSPHERE IS EFFECTIVE FOR DECARBURIZING, RECRYSTALLIZING, DEVELOPING A LARGE GRAIN SIZE AND IMPROVING THE MAGNETIC CHARACTERISTICS OF THE STEEL, THE STEPS COMPRISING, HOT ROLLING THE SILICON STEEL TO A STRIP HAVING A THICKNESS OF BETWEEN 0.060 AND 0.125 INCH, DESCALING, COLD ROOLING THE DESCALED HOT ROLLED STRIP TO A FINAL THICKNESS OF BETWEEN 0.014 AND 0.031 INCH, AND NORMALIZING THE STEEL, THE NORMALIZING HEAT TREATMENT BEING EFFECTED BY PASSING THE SCALE-FREE COLD ROLLED STRIP THROUGH A CONTINUOUS FURNACE IN A TIME PERIOD RANGING BETWEEN 3.5 AND 8 MINUTES, SAID FURNACE HAVING TWO CONTIGUOUS TEMPERTURE ZONES AND A COMMON ATMOSPHERE, IN WHICH THE TEMPERATURE ZONES IN SAID FURNACE PROGRESSIVELY INCREASED IN TEMPERATURE FROM NOT LESS THAN 1400*F. UP TO A HIGH TEMPERATURE ZONE OF BETWEEN 1725*F. AND 2150*F. IN PREDETERMINED INCREMENTS, THE FURNACE HAVING A LOW TEMPERATURE ZONE OF BETWEEN 1400*F. AND 1650*F. AND COMPRISING BETWEEN ABOUT 38% TO ABOUT 49% OF THE TOTAL LENGTH OF THE FURNACE, ADMITTING A CONTROLLED ATMOSPHERE OF A HYDROGEN-CONTAINING PROTECTIVE GS ATMOSPHERE HAVING A DEW POINT OF LESS THAN +60*F. ADJACENT THE STRIP EXIT END OF THE HIGH TEMPERATURE ZONE OF THE FURNACE TO FLOW THROUGHOUT THE FURNACE COUNTERCURRENT TO THE DIRECTION OF MOVEMENT OF THE STRIP THERETHROUGH, SAID ATMOSPHERE BEING COMMON TO BOTH THE HIGH TEMPERATURE ZONE AND THE LOW TEMPERATURE ZONE OF THE FURNACE, THE FURNACE ATMOSPHERE HAVING A MINIMUM OF 12% HYDROGEN BY VOLUME AND REACTING AT LEAST IN THE LOW TEMPERATURE ZONE OF THE FURNACE TO PROVIDE A DEW POINT IN EXCESS OF +60* F. THEREIN, THE FURNACE ATMOSPHERE HAVING A DEW POINT IN EXCESS OF +60*F. COOPERATING WITH THE CARBON OF THE STRIP IN THE LOW TEMPERATURE ZONE OF THE FURNACE TO EFFECTIVELY DECREASE THE CARBON CONTENT OF THE STRIP IN THE LOW TEMPERATURE ZONE OF THE FURNACE TO PRODUCE A FINAL STRIP AT THE EXIT END OF THE FURNACE HAVING A CARBON CONTENT OF BELOW 0.031%, THE HYDROGEN CONTENT OF THE PROTECTIVE GAS ATMOSPHERE COOPERATING WITH THE STRIP IN THE HIGH TEMPERATURE ZONE OF THE FURNACE TO MAINTAIN A SCALE-FREE SURFACE THEREON.