TUBING STOCK MADE FROM ALLOYED, MOLYBDENIUM-CONTAINING STEEL Russian patent published in 2008 - IPC C21D8/10 C22C38/60 

FIELD: metallurgy.

SUBSTANCE: invention concerns metallurgy field. Particularly it concerns manufacturing of tubing stock of diameter from 80 till 180 mm. For providing of increased level of consumer properties stock is made from steel containing mass %: carbon 0.35-0.41, manganese 0.50-0.80, silicon 0.17-0.37, chrome 0.50-0.80, molybdenum 0.08-0.14, niobium 0.005-0.06, vanadium 0.005-0.12, copper 0.005-0.25, 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 admixtures - the rest, at ratio: (As+Sn+Pb+5×Zn)≤0.07; [C+Mn/6+(Cr+Mo+V+Nb)/5]≤0.71. Admixtures (mass%): phosphorus not more than 0.045 sulphur not more than 0.045, nickel not more than 0.25. Stock is made as continuously cast, hot-rolled, thermorefined has is of lamellar ferrite-pearlitic structure, dimension of valid grain 6-9 points. Macrostructure - center porosity, spot heterogeneity, segregation square, subshrink segregation is not more than 3 points for each kind, segregation streaks are not more than 1 point. Nonmetallic inclusions: sulphides, spot oxides, stitch oxides, fragile silicates, flexible silicates, non-strained silicates are not more than 4.0 points for each kind of inclusions. Mechanical properties of stock - tensile strength is not less than 600 N/mm², yield strength is not less than 430 N/mm², percentage elongation is not less than 15%, contraction ratio is not less 40%.

EFFECT: receiving of steel tubing stock with high technological properties.

5 cl, 3 ex