HIGH-STRENGTH SEAMLESS STAINLESS STEEL PIPE FOR OIL-FIELD RANGE TUBULAR GOODS AND METHOD OF ITS PRODUCTION Russian patent published in 2019 - IPC C22C38/46 C21D8/10 

FIELD: metallurgy.

SUBSTANCE: invention relates to the field of metallurgy, namely to high-strength seamless pipe from stainless steel for tubular products of oil-field range, having tensile yield point, which is 862 MPa or more. Pipe is made of steel with the following chemical composition, wt%: 0.05 or less, Si 0.5 or less, Mn from 0.15 to 1.0, P 0.030 or less, S 0.005 or less, Cr from 14.5 to 17.5, Ni from 3.0 to 6.0, Mo from 2.7 to 5.0, Cu from 0.3 to 4.0, W from 0.1 to 2.5, V from 0.02 to 0.20, Al 0.10 or less, N 0.15 or less, Fe and unavoidable impurities – the rest. Content of C, Si, Mn, Cr, Ni, Mo, Cu and N satisfy relation –5.9×(7.82+27C–0.91Si+0.21Mn–0.9Cr+Ni–1.1Mo+0.2Cu+11N)≥13.0, and content of Cu, Mo, W, Cr and Ni ratio Cu + Mo + W + Cr + 2Ni≤34.5. Steel pipe has a structure which includes as the main phase more than 45 % of martensite in terms of volume, and as a secondary phase from 10 to 45 % of the ferrite phase and 30 % or less of the residual austenite phase with respect to volume. Aggregate amount of Cr, Mo and W emissions is equal to 0.75 wt% or less.

EFFECT: produced pipes have excellent low-temperature impact strength, resistance to carbonic corrosion, resistance to sulphide corrosion cracking under stress and resistance to sulphide cracking under stress.

6 cl, 2 tbl