TUBE STOCK OUT OF MEDIUM CARBON MEDIUM 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 designed for fabricating of seamless tubes of various applications. To facilitate upgraded level of consumer characteristics the tube stock is made out of steel, containing wt %: C - (0.37-0.44), Mn - (0.80-1.10), Si - (0.20-0.35), Cr - (0.90-1.20), Mo - (0.15-0.25), Ni - (0.01-0.40), N - (0.005-0.010), As - (0.0001-0.03), Sn - (0.0001-0.02), Pb - (0.0001-0.01), Zn - (0.0001-0.005), iron and unavoidable impurities - the rest, at a following ratio (As+Sn+Pb+5×Zn)≤0.07; 0.85≤(C+Mn/6+Cr/5+Mo)≤1.05, continuous cast, hot rolled and normalized. As impurities steel contains, wt %: posphorus not more, than 0.20, sulphur not more, than 0.012, copper not more, than 0.20. The stock has ferrite-pearlite structure and the dimension of the actual grain is 5-10 points, macrostructure for central porosity, pointed non-uniformity, liquation square is not more, than 2.0 points, sub-shrinking liquation - not more, than 2.0 points, liquation strips are not more, than 1 point, non metallic inclusions of pointed sulphides, pointed oxides, stripped oxides, fragile silicates, plastic silicates, non deformed silicates are not more, than 3.0 points for each kind, tensile strength is 686 N/mm², yield point is not more, than 441^{N/mm2, specific elongation is not less, than 12%, impact resiliense KCV (+20°C) is not less, than 39.2 J/cm2, hardness HB is 217-255.}

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

2 cl, 1 ex