METHOD OF HEAT TREATMENT OF STEEL STRIP IN BELL-TYPE FURNACE Russian patent published in 2005 - IPC

FIELD: metallurgy; heat treatment of steel strips in bell-type furnaces.

SUBSTANCE: proposed method includes heating by bell-type furnace and stand thermocouples in accordance with preset temperatures of holding at heat at stepped heating; strip subjected to heat treatment in shielding atmosphere has rolling emulsion on its surface at intermediate and final holding at heat at temperatures equal to and exceeding temperature of beginning of recrystallization of heat-treated metal by 90-110°C by stand thermocouple and exceeding point Ac₁ by 80-90°C by bell-type furnace thermocouple; upon completion of first holding at heat by stand thermocouple at temperature of beginning of recrystallization, preset temperature is increased by 30-40°C by bell-type furnace thermocouple as compared with initial magnitude and heating is continued till completion of drawing by temperature of stand thermocouple exceeding temperature of beginning of recrystallization by 90-110°C; removal of sublimation products and products of decomposition of emulsion is performed continuously from beginning till completing of heating by blowing the under-muffle space with shielding atmosphere containing 4.0-7.5% of H₂ and 91.5-96.0 of N₂.

EFFECT: improved quality of surface and complex of mechanical properties, microstructure, crystallographic texture in drawing parts of laminar structure.

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