STEEL TUBE FROM LOW ALLOY FOR OIL WELLS Russian patent published in 2018 - IPC C21D9/08 C22C38/06 C22C38/22 C21D8/10 

FIELD: metallurgy.

SUBSTANCE: steel pipe of low alloy oil-well alloy in accordance with present invention has following chemical composition, wt%: C is more than 0.35 and up to 0.65, Si from 0.05 to 0.50, Mn from 0.10 to 1.00, Cr from 0.40 to 1.50, Mo from 0.50 to 2.00, V from 0.05 to 0.25, Nb from 0.01 to 0.040, solution Al from 0.005 to 0.10, N 0.007 or less, Ti from 0 to 0.012, Ca from 0 to 0.005, with residue representing Fe and impurities, impurities being: P 0.020 or less, S 0.002 or less, O 0.006 or less, Ni 0.10 or less, Cu 0.03 or less, and B 0.0005 or less, wherein microstructure includes cementite particles each having equivalent circle diameter of 200 nm or greater in amount of 200 particles / 100 mcm² or more, and yield strength is 827 MPa or more.

EFFECT: resistance to sulfide stress cracking.

3 cl, 3 tbl