TUBE STOCK OUT OF LOW CARBON LOW ALLOYED STEEL Russian patent published in 2008 - IPC C21D8/10 C22C38/60 

FIELD: metallurgy.

SUBSTANCE: invention refers to metallurgy, particularly to production of tube stock with diameter from 80 to 180 mm. To upgraded level of consumer characteristics at the optimal ratio of hardness, plasticity and viscosity the stock is made out of steel, containing wt %: carbon 0.19-0.24, manganese 1.30-1.45, silicon 0.35-0.55, aluminium 0.020-0.060, chromium 0.005-0.30, nitrogen 0.005-0.015, arsenic 0.0001-0.03, tin 0.0001-0.02, lead 0.0001-0.01, zinc 0.0001-0.005, iron and unavoidable impurities - the rest at maintaining the following ratio: As+Sn+Pb+5×Zn≤0.07; C+Mn/6+Cr/5≤ 0.4B. The stock has ferrite-pearlite structure with the dimension of the actual grain of 6-9 points, macrostructure for central porosity, pointed non-uniformity, liquation square, subshrinking liquation is not more, than 3 points for each kind, for liquation strips is not more, than 2 point, non-metallic inclusions for sulphides, pointed oxides, stripped oxides, fragile silicates, plastic silicates and non-deformed silicates are not more, than 4.0 points for each kind, tensile strength is 490-640 N/mm², yield point is not less, than 345 N/mm², specific elongation is not less, than 21%. As unavoidable impurities steel contains wt %: niobium not more, than 0.02, chromium not more, than 0.030, nickel not more, than 0.030, copper not more, than 0.30. The tube stock possesses an optimal ratio of hardness, plasticity and viscosity.

EFFECT: production of tube stock possessing an optimal ratio of hardness, plasticity and viscosity.

2 cl, 1 ex