STRIPS PRODUCING METHOD FOR MAKING CASING TUBES Russian patent published in 2008 - IPC C21D8/02 C22C38/46 

FIELD: metallurgy, namely rolled stock production, possibly manufacture of strips for making electrically welded casing tubes designed for operating in oil and gas wells at condition of Far North in continuous rolling mills.

SUBSTANCE: method comprises steps of heating steel slabs, rough rolling of them till intermediate thickness and finish rolling at normalized temperature of rolling process termination, water cooling of blank till coiling temperature. In order to realize such method steel of next composition (mass %) is used: carbon, 0.14 - 0.19; silicon, 0.15 - 0.40; manganese, 0.8 - 1.2; aluminum, 0.01 - 0.05; titanium, 0.01 - 0.03; vanadium, 0.002 - 0.01; niobium, 0.03 - 0.07; molybdenum, 0.10 - 0.20; chrome, equal to or less than 0.10; nickel, equal to or less than 0.10; copper, equal to or less than 0.10; phosphorus, equal to or less than 0.015; sulfur, equal to or less than 0.005; calcium, equal to or less than 0.005; nitrogen, equal to or less than 0.010; iron, the balance. Temperature of rolling process termination is sustained in range 890 - 940°C and coiling temperature is sustained in range 540 - 600°C. In temperature range 940 - 1100°C strip is rolled at total reduction value 75 - 89%.

EFFECT: less loss of yield, improved quality of strip.

3 tbl