HIGH-STRENGTH STEEL SHEET FOR HYDROGEN SULFIDE-RESISTANT MAIN PIPE, THE METHOD FOR ITS MANUFACTURE AND HIGH-STRENGTH STEEL PIPE OBTAINED USING HIGH-STRENGTH STEEL SHEET FOR HYDROGEN SULFIDE-RESISTANT MAIN PIPE Russian patent published in 2023 - IPC C21D8/02 C21D9/46 C22C38/06 C22C38/50 C22C38/58 

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, namely to a high-strength steel sheet for hydrogen sulfide-resistant main pipes, having the uniformity of the steel sheet and suitable for use in main pipelines used for the transportation of crude oil or natural gas, as well as to the method for its manufacture. High-strength steel sheet for hydrogen sulfide-resistant main pipe has a chemical composition containing, by weight %: C: 0.020-0.080, Si: 0.01-0.50, Mn: 0.50-1.80, P: 0.015 or less, S: 0.0015 or less, Al: 0.010-0.080, N: 0.0010-0.0080, Mo: 0.01-0.50 and Ca: 0.0005-0.0050, if necessary, one or more elements selected from a group consisting of: Cu: 0.30 or less, Ni: 0.10 or less, Cr: 0.50 or less, Nb: 0.005-0.1, V: 0.005-0.1, Ti: 0.005-0.1, Zr: 0.0005-0.02, Mg: 0.0005-0.02 and REM: 0.0005-0.02, Fe and unavoidable impurities – the rest. The microstructure of steel at a level of 0.25 mm below the surface of the specified sheet of steel is a bainite microstructure, and the proportion of the area of crystalline grains having an average local disorientation of 0.4 or more in the bainite microstructure is 50% or less. The maximum Vickers hardness 0.25 mm below the surface of the specified steel sheet is 230 HV or less, and the tensile strength is 520 MPa or more.

EFFECT: present invention enables to produce a sheet for hydrogen sulfide-resistant main pipes is characterized by high values of resistance to hydrogen cracking, as well as resistance to sulfide corrosion cracking under stress in environments containing hydrogen sulfide at a partial pressure of more than 1 bar, and resistance to sulfide corrosion cracking under stress in environments with a low partial pressure of hydrogen sulfide 1 bar or less.

3 cl, 1 dwg, 2 tbl, 30 ex