TWO-PHASE STAINLESS STEEL AT HIGH CORROSION RESISTANCE IN AGGRESSIVE MEDIA Russian patent published in 2003 - IPC

FIELD: metallurgy; making corrosion-resistant steels of austenitic ferrite class; shipbuilding; construction of chemicals tankers; oil producing and gas industries; chemical and power engineering. SUBSTANCE: steel may be used in structures working in aggressive media, in aqueous media in particular which contain chloride ions, sulfides and products of oil producing process, in acids of various concentration and in sea water. Temperature interval is from +50 to +350 C. Steel contains components at the following relationship, mas. %: carbon, 0.01-0.03; silicon, 0.3-0.8; manganese, 0.8-1.2; chromium, 24-26; nickel, 6.5-7.5; molybdenum, 3.5-4.5; nitrogen, 0.15-0.30; sulfur, 0.001-0.015; phosphorus, 0.001- 0.020; copper, 0.1-0.5; calcium, 0.01-0.023; cerium, 0.001-0.02; magnesium, 0.01-0.04; iron, the balance, provided calcium/sulfur ratio ≥1,5. is satisfied. Said steel possesses high resistance to pitting corrosion. EFFECT: enhanced strength and ductility of steel at hot deformation. 2 tbl