TUBING STOCK MADE FROM CHROME-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 100 till 180 mm, intended for weldless drawn pipe manufacturing for heat-and-power engineering. For realisation of technical result stock is made from steel containing further components ratio mass %: carbon 0.07-0.15, manganese 0.40-0.70, silicon 0.7-0.37, chrome 0.80-1.10, molybdenum 0.40-0.55, copper 0.005-0.25, nickel 0.005-0.30, nitrogen 0.005-0.015, iron and unavoidable admixtures - the rest. In the capacity of unavoidable admixtures steel contains, mass %: niobium not more than 0.02, vanadium not more than 0.02, sulphur not more than 0.025, phosphorus not more than 0.035. Stock is made as continuously cast, hot-rolled, at that stock is of lamellar ferrite-pearlitic structure, dimension of valid grain 5-8 points. Macrostructure: center porosity, spot heterogeneity, segregation square, subshrink segregation is not more than 2 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 after normalisation - tensile strength is not less than 400-600 N/mm², yield strength is not less than 290 N/mm², percentage elongation is not less than 22%, contraction ratio is not less 45%.

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

2 cl, 1 ex