HIGH-STRENGTH OIL COUNTRY TUBULAR GOOD IN COLD-RESISTANT PERFORMANCE (OPTIONS) Russian patent published in 2019 - IPC F16L9/02 C22C38/00 

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, in particular to the manufacture of high-strength tubing and casing pipes located in climatic regions with an ambient temperature of minus 60 °C. Pipe is made of steel, which is subjected to quenching and high tempering at the temperature not lower than 540 °C and contains components in the following ratio wt %: carbon 0.23–0.35; silicon 0.15–0.45; manganese 0.30–1.20; chromium 0.40–1.30; aluminum 0.02–0.05; sulfur is not more than 0.015; phosphorus is not more than 0.020; nitrogen is not more than 0,012; iron and inevitable impurities, including nickel and copper – the rest. According to the second option, the pipe is made of steel and contains the components specified in the first option, and also molybdenum is 0.10–1.00 wt %, vanadium is not more than 0.12 wt % and niobium is not more than 0.05 wt %. Size of the initial grain of austenite steel shall not be larger than 8 points.

EFFECT: invention provides for the strength properties of the metal of a cold-resistant oil country tubular good with the wall thickness of 15 mm and more, corresponding to the strength groups from D to P (yield strength from 379 MPa to 1137 MPa).

4 cl, 3 tbl