HIGH-STRENGTH SEAMLESS PIPE OF STAINLESS STEEL OF OILFIELD RANGE AND METHOD FOR MANUFACTURE THEREOF Russian patent published in 2016 - IPC C21D8/10 C21D9/08 C22C38/00 

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, particularly, to production of high-strength stainless steel pipes of oil-field range with wall thickness of more than 25.4 mm. To provide high strength equal to 758 MPa, impact strength and corrosion resistance of steel material containing, wt. %: C 0.005 or more, and 0.06 or less, Si 0.05 or more and 0.5 or less, Mn 0.2 or more and 1.8 or less, P 0.03 or less, S 0.005 or less, Cr 15.5 or more and 18.0 or less, Ni 1.5 or more and 5.0 or below, V 0.02 or more and 0.2 or less, Al 0.002 or more and 0.05 or less than , N 0.01 or more and less than 0.15, O 0.006 or less than one, two or more elements selected from: Mo 1.0 or more and 3.5 or less, W 3.0 or less and Cu 3.5 or less, when performing the following conditions: Cr + 0.65 Ni + 0.60 Mo + 0.30 W + 0.55 Cu - 19.5 ≥ 20 C and Cr + Mo + 0.50 W + 0.30 Si - 43.5 C 0.4 - Mn - Ni - 0.3 Cu - 11.5 ≥ 9 N, heated and hot rolling.

EFFECT: hot rolling is performed in the range of temperatures 1,100 °C-900 °C with total reduction making 30 % or more, then cooling the cooling rate equal to or higher speed of air cooling, and also quenching-tempering.

6 cl, 1 dwg, 3 tbl