TUBE STOCK OUT OF MICRO 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 facilitate upgraded level of consumer characteristics at a minimal level of anisotropy of mechanical properties the tube stock is fabricated continuous cast, hot rolled, out of steel, containing, wt %: carbon 0.14-0.20, manganese 1.00-1.40, silicon 0.03-0.10, titanium 0.002-0.03, aluminium 0.02-0.05, vanadium 0.002-0.02, sulphur 0.005-0.012, phosphorus 0.005-0.013, 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 the ratio: As+Sn+Pb+5xZn<0.07, C+Mn/6+V/5≤0.40. As impurities steel contains wt %: niobium not more, than 0.02, chromium not more, than 0.30, nickel not more, than 0.30, copper not more, than 0.30. The stock has ferrite-pearlite structure with the dimension of the actual grain of 6-9 points. It also has macrostructure for central porosity, pointed non-uniformity, liquation square and subshrinking liquation not more, than 3 points for each kind, and liquation strips - not more, than 1 points. Non-metallic inclusions for sulphides, pointed oxides, stripped oxides, fragile silicates, plastic silicates and non-deformed silicates are not more, than 5.0 points for each kind. Tensile strength is not less, than 480 N/mm², yield point is not less, than 335 N/mm², specific elongation is not less, than 23%, impact viscosity KCU+20°C is not less, than 49 J/mm².

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

1 cl, 1 ex