CORROSION-RESISTANT PIPE FROM LOW-CARBON PRE-PERITIC STEEL FOR OIL AND GAS PIPELINES AND METHOD OF ITS MANUFACTURE Russian patent published in 2018 - IPC C21D8/10 C21D9/08 C22C38/12 

FIELD: metallurgy.

SUBSTANCE: pipe is made of steel containing, wt %: C less than 0.08, Mn 1.10÷1.60, Si 0.15÷0.50, V 0.030÷0.11, Nb 0.040÷0.080, Al 0.005÷0.060, N 0.005÷0,015, Fe and unavoidable impurities are the rest, when the relation is ([C]+[Mn]/6-[Si]/7+[N]/1,4)≤0.23 and providing a ferrite potential of not less than 1, then the pipe is subjected to hot deformation at 880÷1350°C and heat treatment by heating to A_c3+(30÷45°C), water cooling and subsequent high tempering at temperature A_c1-(50÷150)°C with holding time of at least 4 minutes per 1 mm of thickness of the pipe wall providing for a microstructure consisting of a finely dispersed ferritic carbide mixture.

EFFECT: production of pipes with the required strength and viscoplastic characteristics and high corrosion resistance in a sulfide-containing medium under pressure.

2 cl, 1 dwg, 4 tbl