METHOD FOR PRODUCTION OF COLD-ROLLED COILED STEEL Russian patent published in 2009 - IPC C21D8/04 C21D9/48 C21D9/663 

FIELD: technological processes.

SUBSTANCE: invention is related to rolled production, in particular to production of thin-sheet cold-rolled coiled steel with thickness of up to 0.5 mm. In order to improve quality of sheet steel due to reduction of defects of its surface: scratches, fractures and slide lines, semi-finished rolled products are exposed to cold rolling to produce strip with thickness of less than 0.5 mm, winding in coil, annealing and temper rolling, at the same time cold rolling is carried out in two stages with total clamping of semi-finished rolled products with thickness of h₁=1.5 mm within the limits of 70-72%, and semi-finished rolled products with h₂=1.8-2.0 mm - 73-74% on notched rollers of the first mill in double-stand reversing mill with roughness of their barrels Ra=2-3 mcm, with establishment of the following specific tension on reeler drum for strips with width of up to 1.2 m - 70 N/mm², and for strips with width of higher than 1.2 to 1.28 m - 60 N/mm² with added tension in both cases than makes 70 N/mm², cooling after annealing of strips with thickness of less than 0.5 mm is carried out as follows: at the first stage after stage of heating up to temperature of t₁ by 30°C below temperature of final maintenance with the rate of 7.5 degree/hr, and the second stage - from temperature t₁ to 600°C according to bench thermocouple with the rate of 8 - 20 degree/hr and duration of 3 hr, at the third stage under heating hood with disconnected burners during 5 hr, finally cooled with water from temperature of 250-280°C according to bench thermocouple, and tempering of annealed strips is carried out with clamping of 1.1±0.1%.

EFFECT: improvement of sheet steel quality due to reduction of its surface defects.

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