HIGH-STRENGTH AUSTENITIC STAINLESS STEEL AND METHOD OF FINAL HARDENING OF ARTICLES MADE FROM SUCH STEEL Russian patent published in 2005 - IPC

FIELD: production of high-strength austenitic stainless steel for casing pipes and oil tubing of gas and oil fields at high content of hydrogen sulfide.

SUBSTANCE: proposed steel includes the following components, mass-%: C≤0.05; Cr, 24-28; Ni25-40; Mo, 2-5; Cu, 1-3; W≤3; Mn≤2.5; Si≤0.2; V≤0.15; Nb≤0.1; Ti≤0.2; Al≤0.1; rare-earth metals≤0.05; N≤0.11; S≤0.01; P≤0.02; the remainder being iron. Mo+W≤6 mass-%; V+Nb≤0.2 mass-% and 1.10<%Ni[%Cr+0.8(%Mo+%W)]<1.25. Method of final hardening of articles made from proposed steel includes preliminary plastic deformation at reduction no less than 40% and temperature not exceeding the temperature of beginning recrystallization, hardening to solid solution from temperature not below 1020°C and final plastic deformation at degree of 30-70% at temperature below temperature of beginning of recrystallization by 150°C.

EFFECT: increased toughness and ductility of steel; improved technological and corrosion-resistant properties.

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