SEAMLESS OIL-GRADE PIPE MADE OF HIGH-STRENGTH CORROSION-RESISTANT MARTENSITIC STEEL AND METHOD FOR ITS PRODUCTION Russian patent published in 2023 - IPC C22C38/50 C22C38/48 C22C38/46 C22C38/44 C22C38/42 C21D9/08 C21D8/10 F16L9/02 

FIELD: metallurgy.

SUBSTANCE: invention relates to the production of casing and tubing seamless pipes made of stainless high-strength martensitic steel for oil and gas wells located in cold macroclimatic areas characterized by an aggressive working environment. The seamless pipe is made of steel containing components in the following ratio, wt.%: carbon from more than 0.10 to 0.18, manganese 0.3-0.75, chromium 12.0-14.0, nickel 2.2-2.5, molybdenum no more than 0.5, niobium 0.02-0.05, titanium no more than 0.05, silicon 0.1 - no more than 1.0, copper 0.01-0.5, phosphorus no more 0.020, sulphur no more than 0.010, nitrogen no more than 0.05, aluminium no more than 0.10, if necessary vanadium 0.02-0.12, the rest is iron and inevitable impurities. The contents of nickel, carbon, manganese and molybdenum in steel satisfy the following relationship: 5.0<Ni+28C+0.5Mn-0.8Mo<6.5, and the contents of titanium, niobium and vanadium satisfy the following relationship: 4Ti+Nb+0.5V<0.25, where Ni, C, Mn, Mo, Ti, Nb and V are the content of nickel, carbon, manganese, molybdenum, titanium, niobium and vanadium in steel, in wt.%, respectively.

EFFECT: resulting pipes are characterized by a strength group from R95 to P110 with a yield strength from 655 to 965 MPa, a hardness of no more than 32 HRC and impact strength (KCV) at a temperature of minus 60°C not less than 70 J/cm².

4 cl, 3 dwg, 2 tbl