HIGH-STRENGTH MARTENSITE STAINLESS STEEL WITH HIGH CORROSIONPROOFNESS AGAINST GASEOUS CARBON DIOXIDE AND HIGH RESISTANCE AGAINST CORROSION CRACKING UNDER STRESS IN HYDROGEN SULFIDE ATMOSPHERE Russian patent published in 2007 - IPC C22C38/44 C22C38/50 C22C38/58 C21D6/00 

FIELD: martensite stainless steels.

SUBSTANCE: steel contains, mass%: carbon, 0.005 - 0.04; silicon, 0.5 or less; manganese, 0.1 - 3.0; phosphorus, 0.4 or less; sulfur, 0.01 0r less; chrome, 10.0 - 15.0; nickel, 4.0 - 8.0; molybdenum, 2.8 - 5.0; aluminum, 0.001 - 0.10; nitrogen, 0.07 or less; iron and inevitable impurities, the balance. Microstructure of such steel includes 70% or more of tempered martensite, carbides separated during tempering stage, intermetallic compounds such as Laves phase, σ -phase and similar fine-grain phases separated during tempering process. Such steel features high ultimate strength, elastic strength 860 MPa and more.

EFFECT: possibility for making tubes for oil producing wells from such steel due to its high resistance against corrosion cracking and improved resistance against corrosion caused by gaseous carbon dioxide, increased ultimate strength.

9 cl, 2 dwg, 2 tbl, 17 ex