LOW TEMPERATURE RESISTANT OIL CASING PIPE WITH HIGH STRENGTH AND HIGH VISCOSITY, AS WELL AS METHOD FOR ITS MANUFACTURE Russian patent published in 2021 - IPC E21B17/00 C22C38/24 C21D9/14 

FIELD: oil industry.

SUBSTANCE: group of inventions relates to the oil and gas industry, in particular to the production of casing pipes. The mass chemical composition of the oil casing pipe is as follows: C: 0.08-0.14%; Si: 0.1-0.4%; Mn: 0.6-1.3%; Cr: 0.5-1.5%; Mo: 0.2-0.5%; Ni: 0.2-0.5%; Nb: 0.02-0.05%; V: 0-0.1%; Al: 0.01-0.05%; Ca: 0.0005-0.005%, and the rest is Fe and unavoidable impurities. The microstructure contains fine-grained and evenly tempered sorbitol and residual austenite. Grain size number is 10 or more. The method for manufacturing the pipe includes smelting and continuous casting, perforation and continuous rolling, heat treatment, in which the austenization temperature is adjusted in the range of 900-930°C and maintained for 30-60 minutes, followed by quenching, then tempering at a temperature of 480-600°C, with the specified temperature maintained for 50-80 minutes, hot calibration.

EFFECT: increases resistance to low temperatures, provides high strength, high viscosity.

9 cl, 3 dwg