HOT-ROLLED SEAMLESS TUBING WITH INCREASED OPERATIONAL RELIABILITY FOR OIL-FIELD EQUIPMENT Russian patent published in 2020 - IPC C22C38/24 C22C38/26 B21C37/06 C21D8/10 

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, namely to production of hot-rolled seamless tubing with increased operational reliability, which is used for oil-field equipment for production of water-flooded oil and high-mineralized formation water containing carbon dioxide, hydrogen sulphide, chlorine ions, as well as mechanical particles. Seamless tubing string is made from tubular billet of chromium-containing steel, having the following composition, wt%: 0.22 to 0.38 carbon, 0.45 or less of silicon, 0.80 to 1.45 of manganese, 0.020 or less phosphorus, 0.010 or less sulfur, 0.10 or less aluminum, 0.3 to 1.1 chromium, 0.12 or less nitrogen, at least one component selected from: 0.11 or less of vanadium and 0.07 or less of niobium, the rest being iron (Fe) and unavoidable impurities. For steel components the following ratios are met: 0.6≤|C|+|Mn|/4+|Cr|/5≤0.9 and 0.07≤|V|+2x|Nb|≤0.14, where |C|, |Mn|, |Cr|, |V| and |Nb| – absolute value of content, wt%, of carbon, manganese, chrome, vanadium and niobium. Steel may additionally contain at least one of: 0.20 wt% or less of nickel, 0.25 wt% or less of copper and 0.10 wt% or less of titanium. Tubular stock is subjected to piercing, rolling in continuous mill and high-temperature thermomechanical treatment in reduction mill at temperature of 950–1,075 °C with drawing coefficient of 1.2–2.2.

EFFECT: providing required level of strength, increased corrosion resistance and operational reliability.

4 cl, 1 dwg, 3 tbl