STAINLESS STEEL USED FOR OIL COUNTRY TUBULAR GOODS Russian patent published in 2012 - IPC C22C38/58 C22C38/44 

FIELD: metallurgy.

SUBSTANCE: invention refers to metallurgy, and namely to stainless steel used for oil country tubular goods. Steel contains the following, wt %: 0.001 to 0.05 C, 0.05 to 1.0 Si, max. 2.0 Mn, max. 0.03 P, less than 0.002 S, 16.0 to 18.0 Cr, 3.5 to 7.0 Ni, more than 2.0 and max. 4.0 Mo, 1.5 to 4.0 Cu, 0.001 to 0.3 rare-earth metal, 0.001 to 0.1 solution of Al, 0.0001 to 0.01 Ca, max. 0.05 O, max. 0.05 N, Fe and harmful impurities are the rest. Steel can also contain at least one element chosen from the group: max. 0.5 Ti, max. 0.5 Zr, max. 0.5 Hf, max. 0.5 V and max. 0.5 Nb. Steel structure contains, vol %: 10 to 60 of ferritic phase and 2 to 10 of residual austenitic phase.

EFFECT: steel has high stability to stress corrosion cracking (SCC) in high temperature medium of chlorine-containing water solution.

3 cl, 1 dwg, 3 tbl, 1 ex