PROCEDURE FOR PRODUCTION OF STRIP FOR PIPES OF MAINS Russian patent published in 2011 - IPC C21D8/02 C22C38/44 C22C38/48 C21D9/46 

FIELD: metallurgy.

SUBSTANCE: invention refers to production of strip for submarine mains of diameter to 1420 mm, grade of strength X70 and thickness to 40 mm. There is melted steel of specific chemical composition. It is cast to work pieces which are heated to temperature 1150-1200°C during 7-8 hours and are preliminary deformed with summary degree of reduction 58-65 % with controlled reduction 14-20 % at temperature 940-990°C. Further, produced work pieces are cooled at 70-100°C at rate 4-12°C/sec and conditioned for 3-5 sec per mm of cross section of a work piece in air and are finally deformed at temperature 830-750°C with summary degree of reductions not less, than 43 % and not less, than 12 % per pass, where upon a strip is subjected to accelerated cooling to temperature 550-400°C and successively to retarded strip cooling in a caisson to temperature not over 150°C, and finally in air.

EFFECT: high strength properties and resistance to brittle fracture.

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