METHOD FOR PRODUCTION OF ELECTRO-WELDED PIPE MADE OF LOW-CARBON STEEL, RESISTANT TO HYDROGEN CRACKING (OPTIONS) Russian patent published in 2021 - IPC C21D8/10 C22C38/26 C21D9/08 

FIELD: metallurgy.

SUBSTANCE: group of inventions relates to metallurgy, namely, to methods for the production of electro-welded pipes made of low-carbon steels that are resistant to hydrogen cracking, which can be used for the transport of corrosive environments containing, in particular, hydrogen sulfide. Method of production of electro-welded pipe made of low-carbon steel, resistant to hydrogen cracking, containing, wt. %: carbon 0.045÷0.060, manganese 0.50÷1.00, silicon 0.17÷ 0.40, chromium is 0.50÷1.00, copper no more than 0.25, niobium 0.020÷0.045, aluminum 0.01÷0.04, nitrogen no more than 0.008, sulfur no more than 0.002, phosphorus no more than 0.010, calcium 0.001÷0.005 when the conditions are met: Mn/Si>2.5, and Cr/Si=2.0÷3.5, includes the stage of the manufacture of the pipe material, including steel production, its secondary metallurgy and casting, subsequent hot rolling of obtained steel material, and cooling the hot-rolled steel strip; the pipe manufacturing stage, which includes roll forming of a hot-rolled steel strip into a pipe billet, subsequent welding of the edges of the formed pipe billet with high-frequency currents, local heat treatment of the welded joint and volumetric heat treatment of the pipe. The volumetric heat treatment of the pipe corresponding to the ratio d/t<30 is carried out by heating it to a temperature above the point Ac3, quenching and subsequent tempering, and the heat treatment of the pipe corresponding to the ratio d/t≥30 is carried out by heating it to a temperature below the point Ac1, followed by air cooling, where d is the outer diameter of the pipe, mm, t is the wall thickness of the pipe, mm.

EFFECT: invention provides increased resistance of the material of electro-welded pipes against hydrogen cracking while maintaining its strength, viscosity and weldability.

8 cl, 3 tbl