OIL COUNTRY TUBULAR GOODS OF HEAVY-DUTY Russian patent published in 2009 - IPC C21D8/10 C22C38/12 

FIELD: metallurgy.

SUBSTANCE: invention relates to receiving of oil country tubular goods from steels which are microalloyed by strong carbide - and nitride-forming elements. Tubular good is received from the steel, containing, wt %: 0.31-0.34 carbon, 0.30-0.45 silicon, 0.75-0.95 manganese, 0.045-0.100 niobium, 0.001-0.080 vanadium, 0.002-0.004 boron, 0.005-0.006 aluminium, 0.010-0.045 titanium, 1.10-1.50 chromium, 0.001-0.045 sulfur, 0.001-0.045 phosphor, no more than 0.012 nitrogen, no more than 0.50 nickel, no more than 0.20 copper, iron is the rest, with observance of ratio: [chrome]+[vanadium]+[niobium] = 1.15-1.70, hot-rolled at the temperature of hot deformation finish 780-850°C and tempered with austenitising temperature while tempering, equal to 880-900°C and tempering at temperature 600-720°C.

EFFECT: hardening.

1 ex, 2 tbl