TUBE STOCK OUT OF LOW ALLOYED STEEL Russian patent published in 2008 - IPC C21D8/10 C22C38/12 C22C38/42 

FIELD: metallurgy.

SUBSTANCE: invention refers to metallurgy, particularly to production of tube stock with diameter from 100 to 180 mm. To facilitate upgraded level of consumer characteristics at a minimal level of anisotropy of mechanical properties the stock is made continuous cast, hot rolled out of steel, containing elements, wt %: carbon 0.16-0.24, manganese 0.35-0.65, silicon 0.17-0.37, titanium 0.01-0.03, aluminium 0.001-0.060, vanadium 0.005-0.06, nitrogen 0.005-0.008, iron and unavoidable impurities - the rest. As impurities steel contains, wt %: niobium not more, than 0.02, chromium not more, than 0.25, nickel not more, than 0.30, copper not more, than 0.25, molybdenum not more, than 0.15, sulphur not more, than 0.013, phosphorus not more, than 0.018. 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, subshrinking 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. Tensile strength is not less, than 420-550 N/mm², yield point is not less, than 275 N/mm², specific elongation is not less, than 22%, contraction ratio is not less, than 50%.

EFFECT: producing tube stock with upgraded level of consumer characteristics.

2 cl, 1 ex