STRIP MAKING METHOD FOR PRODUCING TUBES Russian patent published in 2007 - IPC C21D8/02 C22C38/44 

FIELD: metallurgy, namely manufacture of strips of low alloy steel in continuous wide strip rolling mills for producing electrically welded tubes designed for building oil- and gas pipelines operating in Far North regions.

SUBSTANCE: method is realized by using steel of next chemical composition, mass %: carbon, 0.05 - 0.09; silicon, 0.15 - 0.40; manganese, 1.0 - 1.4; aluminum, 0.01 - 0.06; titanium, 0.01 - 0.04; vanadium, 0.01 - 0.04; niobium, 0.02 - 0.06; molybdenum, 0.01 or less; chrome, 0.10 or less; nickel, 0.10; copper, 0.10; phosphorus, 0.015 or less; sulfur, 0.006 or less; calcium, 0.005 or less; nitrogen, 0.010 or less; iron, the balance. Content of elements in steel satisfies relation: C +Mn/6 +(Cr + Mo + V + Ti + Nb)/5 + (Ni + Cu)/15 = 0.40 or less. Slabs are heated up to temperature 1200 -1280°C; temperature of rolling process termination is sustained in range 830 - 880°C and coiling process temperature is sustained in range 540 - 580°C.

EFFECT: enhanced viscous properties of steel strips at negative temperatures, high welding capability and ductility of steel strips.

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