TUBE STOCK OUT OF MEDIUM CARBON MICRO ALLOYED STEEL Russian patent published in 2008 - IPC C21D8/10 C22C38/26 

FIELD: metallurgy.

SUBSTANCE: invention refers to metallurgy, particularly to production of tube stock with diameter from 80 to 180 mm. To facilitate optimal ratio of hardness, plasticity and viscosity the stock is made out of steel, containing wt %: carbon 0.40-0.50, manganese 0.80-1.40, silicon 0.17-0.37, chromium 0.005-0.25, niobium 0.040-0.11, molybdenum 0.001-0.12, iron and unavoidable impurities - the rest; the stock has ferrite-pearlite structure, the dimension of the actual grain is 5-8 points, its macrostructure for central porosity, pointed non-uniformity, liquation square, subshrinking liquation - not more, than 2 points for each kind, liquation strips - not more, than 1 point, non-metallic inclusions - sulphides, pointed oxides, stripped oxides, fragile silicates, plastic silicates, non-deformed silicates - not more, than 4.0 points for each kind of inclusions, tensile strength is not less, than 500 N/mm², yield point is not less, than 390 N/mm², specific elongation is not less, than 20%. As unavoidable impurities steel contains wt %: niobium not more, than 0.02, arsenic not more, than 0.03, tin not more, than 0.02, lead not more, than 0.01, zinc not more, than 0.005, nitrogen not more, than 0.010, copper not more, than 0.25, nickel not more, than 0.25, sulphur not more, than 0.045, phosphorus not more, than 0.045.

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

2 cl, 1 ex