LOW ALLOYED WELD STEEL Russian patent published in 2008 - IPC C22C38/50 C22C38/28 C22C38/16 C22C38/14 

FIELD: metallurgy.

SUBSTANCE: invention refers to low alloyed steel used for fabrication of weld oil and gas pipelines operated under conditions of the Extreme North. Steel contains carbon, silicon, manganese, vanadium, niobium, aluminium, titanium, nitrogen, chromium, nickel, copper, sulphur, phosphorus, calcium and iron at a following ratio of components, wt %: carbon 0.05-0.15; silicon 0.30-0.90; manganese 0.40-0.90; vanadium 0.04-0.15; niobium 0.02-0.08; aluminium 0.02-0.06; titanium 0.005-0.03; nitrogen not more, than 0.008; chromium not more, than 0.30; nickel not more, than 0.30; copper not more, than 0.30; sulphur not more, than 0.005; phosphorus not more, than 0.018; calcium 0.001-0.006; iron - the rest. In its structure steel has ferrite with number of grain not less, than 9 at a structure striation not more, than 2 points and nonmetallic inclusions not bigger, than 3 points. Total contents of chromium, nickel and copper meets the condition: Cr + Ni + Cu ≤ 0.6 wt %.

EFFECT: upgraded corrosion and cold resistance and output of ready for service hot-rolled strip bar.

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