TUBE STOCK OUT OF MEDIUM CARBON MANGANESE CONTAINING 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 90 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 - (0.30-0.33), Mn - (0.70-1.20), Si - (0.20-0.35), Cr - (0.005-1.10), Al - (0.02-0.05), S - (0.001-0.020), P - (0.005-0.020), N - (0.005-0.012), As - (0.0001-0.03), Sn - (0.0001-0.02), Pb - (0.0001-0.01), Zn - (0.0001-0.005), iron and unavoidable impurities at a following ratio: (As+Sn+Pb+5×Zn)≤0.07; 0.42≤(C+Mn/6+Cr/5)≤0.73, at that it is fabricated hot rolled, then is subject to normalisation and has ferrite-pearlite structure, the dimension of the actual grain 5-10 points, macrostructure for central porosity, pointed non-uniformity, liquation square not more, than 2.0 points, sub-shrinking liquation and liquation strips - not more, than 1 point, non metallic inclusions of pointed sulphides, pointed oxides, stripped oxides, fragile silicates, plastic silicates, non deformed silicates - not more, than 2.5 points for each kind of inclusions. As impurities steel contains, wt %: nickel not more, than 0.25, copper not more, than 0.25, molybdenum not more, than 0.08, mechanical properties after normalisation are: tensile strength 430-610N/mm², yield point is not more, than 300^{N/mm2, specific elongation is not less, than 18%, impact resilience KCV (+20°C) not less, than 30.2 J/cm2.}

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

6 cl, 4 ex