TUBING STOCK MADE FROM ALLOYED 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 receiving favourable correlation between strength, flexibility and sluggishness tubing stock is made from steel containing mass %: carbon 0.16-0.21, manganese 0.70-1.10, silicon 0.17-0.37, chrome 0.80-1.10, nickel 0.80-1.10, molybdenum 0.005-0.11, vanadium 0.002-0.015, titanium 0.001-0.015, sulphur 0.020-0.035, calcium 0.001-0.010, 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 unavoidable admixtures - the rest, at fulfillment of following components ratio As+Sn+Pb+5×Zn≤0.07; Ca /S≥0.065; C+Mn/6+(Cr+Mo+V)/5+Ni/15≤0.70. In the capacity of unavoidable admixtures steel contains (mass%) niobium not more than 0.02, phosphorus not more than 0.035. Rolled stock is of lamellar ferrite-pearlitic structure, dimension of valid grain is - 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 2 points. Nonmetallic inclusions: sulphides, spot oxides, stitch oxides, fragile silicates, flexible silicates, non-strained silicates - not more than 4.0 points for each kind of inclusions. Mechanical properties after normalisation - tensile strength is not less than 485 N/mm², yield strength is not less than 320 N/mm², percentage elongation is not less than 18%.

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

2 cl, 1 ex