TUBE STOCK OUT OF LOW ALLOYED STEEL Russian patent published in 2008 - IPC C21D8/10 C22C38/14 C22C38/42 

FIELD: metallurgy.

SUBSTANCE: invention refers to metallurgy, particularly to production of tube stock with diameter from 80 to 160 mm. The stock is made continuous cast, hot rolled our of steel, containing the following ratio of elements, wt %: carbon 0.16-0.24, manganese 1.10-1.60, silicon 0.12-0.17, chromium 0.005-0.30; vanadium 0.08-0.14, aluminium 0.02-0.04, copper 0.005-0.30; nickel 0.005-0.30; nitrogen 0.005-0.015, iron and unavoidable impurities - the rest, and as impurities steel contains (wt %) niobium not more, than 0.02, titanium not more, than 0.03, molybdenum not more, than 0.10, sulphur not more, than 0.030, phosphorus not more, than 0.030. The stock has ferrite-pearlite structure, the dimension of the actual grain is 5-8 points, for macrostructure - the central porosity, pointed non-uniformity, liquation square, sub-shrinking liquation - not more, than 2 points for each kind, liquation strips - not more, than 1 point, for non-metallic inclusions - sulphides, pointed oxides, stripped oxides, fragile silicates, plastic silicates, non-deformed silicates - not more, than 4.5 points for each kind of inclusions. The mechanical properties are: ultimate tensile strength not less, than 450 N/mm², yield point is not less, than 350 N/mm², specific elongation - not less, than 18%, impact elasticity at an ambient temperature KCU - not less, than 30 J/cm².

EFFECT: facilitating of optimal combination of hardness, plasticity and viscosity and minimal level of anisotropy of mechanical properties of tube stock.

2 cl, 1 ex