FIELD: metallurgy.
SUBSTANCE: invention relates to metallurgy, particularly, to steel material used in oil and gas wells. Material has the following chemical composition in wt. %: C: more than 0.50 to 0.80, Si: 0.05 to 1.00, Mn: 0.05 to 1.00, P: 0.025 or less, S: 0.0100 or less, Al: 0.005 to 0.100, Cr: 0.20 to 1.50, Mo: 0.25 to 1.50, Ti: 0.002 to 0.050, B: 0.0001 to 0.0050, N: 0.002 to 0.010, O: 0.0100 or less, V: from 0 to 0.30, Nb: from 0 to 0.100, Ca: 0 to 0.0100, Mg: 0 to 0.0100, Zr: 0 to 0.0100, Co: 0 to 0.50, W: 0 to 0.50, Ni: 0 to 0.50, Cu: 0 to 0.50, the balance is iron and impurities, wherein the amount of dissolved C is in range of 0.010–0.060 wt. %.
EFFECT: material has yield point in range of 965–1069 MPa, yield strength to ultimate strength ratio of 90 % or more, as well as excellent resistance to sulphide cracking under stress.
18 cl, 2 dwg, 3 tbl
