TUBE STOCK OUT OF LOW CARBON MANGANESE CONTAINING STEEL Russian patent published in 2008 - IPC C21D8/10 C22C38/60 C22C38/48 

FIELD: metallurgy.

SUBSTANCE: invention refers to metallurgy, particularly to production of tube stock with diameter from 75 to 180 mm. To facilitate upgraded level of consumer characteristics at optimal combination of hardness, plasticity and viscosity the stock is made out of steel, containing wt %: carbon 0.06-0.12, manganese 1.30-1.70; silicon 0.50-0.80, chromium 0.005-0.30, nickel 0.005-0.30; copper 0.005-0.30, sulphur 0.005-0.040, phoshorus 0.005-0.040, calcium 0.001-0.010, nitrogen 0.005-0.015, arsenic 0.0001-0.01, tin 0.0001-0.02, lead 0.0001-0.01, zinc 0.0001-0.005, iron and unavoidable impurities at maintaining of ratio: As+Sn+Pb+5×Zn≤0.055, calcium/sulphur ≥0.055, C+Mn/6+Cr/5+(Ni+Cu)/15≤0.45, continuous cast and hot rolled. As impurities steel contains wt %: niobium not more, than 0.02, vanadium not more, than 0.02. The stock has laminar ferrite-pearlite structure, the dimension of the actual grain is 6-9 points. Its macrostructure for central porosity, pointed non-uniformity, liquation square, sub-shrinking liquation - not more, than 3 points for each kind, liquation strips - not more, than 2 points. 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, ensile strength is not less, than 315 N/mm², yield point is not less, than 260 N/mm², specific elongation is not less, than 25%, impact resilience KCU+20°C not less, than 49 J/mm².

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

2 cl, 1 ex