METHOD OF PRODUCING ROLLED METAL FOR MAKING PIPES OF STRENGTH CATEGORY K48-K56, RESISTANT TO HYDROGEN SULPHIDE CRACKING AND GENERAL CORROSION, AND PIPE MADE FROM IT Russian patent published in 2019 - IPC C21D8/02 C22C38/00 

FIELD: metallurgy.

SUBSTANCE: invention relates to the field of metallurgy. To achieve technical result, method of rolled metal production includes steel melting, out-of-furnace treatment with application of evacuation means with provision of hydrogen content in steel of not more than 2 ppm, continuous casting of steel on slabs, heating of slabs to temperature of 1,150–1,250 °C, preliminary and final rolling with accelerated cooling. Steel contains, wt %: C 0.02–0.08, Mn 0.30–1.2, Si 0.10–0.70, Nb 0.005–0.09, Al 0.025–0.045, Ti 0.01–0.023, Ni 0.01–0.3, Cu≤0.3, Cr≤1.0, N≤0.0045, S≤0.0015, P≤0.010, V≤0.10, Ca 0.0005–0.006, Ba 0.0005–0.006, iron and unavoidable impurities – balance at performance of ratios of 10×C+Mn+(1-10×Nb)=2±0.4, as well as Ca/S=1.5÷2.5. Segregation coefficient does not exceed 1.5. Heated slabs are subjected to rolling in 2–4 stages, at that, total reduction of slabs at preliminary stage is 40-70 % with the multiplicity of the rolled product relative to the thickness of the finished product, equal to 3.2–5.2, and parameters of rolling at final stage are determined depending on content in chromium steel. Produced rolled metal with thickness of 9.0 mm to 30.0 mm is accelerated to 350–650 °C at rate of 10–30 °C/s, after which sheets with thickness of 12 mm and more are cooled in the area of slow cooling, and sheets with thickness of less than 12 mm are cooled in calm air.

EFFECT: production of rolled sheet and pipes with increased resistance to hydrogen and hydrogen sulphide cracking under stress, resistance to general corrosion, as well as low-temperature viscosity with temperature of viscoelastic transition (T₅₀) less than -40 °C, impact viscosity value (KCV^-40) more than 250 J/cm².

5 cl, 6 tbl