METHOD OF ANNEALING FOR SECONDARY RECRYSTALLIZATION OF ANISOTROPIC COLD-ROLLED ELECTRICAL SHEET STEEL WITH HEATPROOF COATING Russian patent published in 1998 - IPC

FIELD: production of anisotropic cold-rolled strip 0!17-0!35 mm thick with heatproof coating from metal containing silicon in the amount of 3% and with annealing for secondary recrystallization. SUBSTANCE: cold-rolled products with surface coated with magnesium oxide of different grade of hydration are rolled into coils weighing 5-8 t each and subjected to annealing for secondary recrystallization in protective nitrogen-hydrogen and hydrogen atmosphere. In course if the entire cycle of annealing, consumption of protective atmosphere amounts to 1.4-1.6 ncu.m/h per ton of annealed metal with gage pressure in furnace of 3-7 mm hG and on the boundary between regions of the primary and secondary recrystallization, heating is carried out in furnace protective atmosphere with dew point of plus 3 to minus 3 C. EFFECT: higher efficiency. 1 tbl