LOW-ALLOY STEEL WITH HIGH RESISTANCE AGAINST SULFIDE CRACKING FOR TUBULAR GOODS Russian patent published in 2010 - IPC C22C38/12 

FIELD: metallurgy.

SUBSTANCE: steel contains carbon, silicon, manganese, phosphorus, sulphur, aluminium, molybdenum, vanadium, boron, nitrogen, oxygen and iron, at following components ratio, wt %: carbon 0.20-0.35, silicon 0.05-0.5, manganese 0.05-0.6, phosphorus not more than 0.025, sulphur not more than 0.01, aluminium 0.005-0.100, molybdenum 0.8-3.0, vanadium 0.05-0.25, boron 0.0001-0.005, nitrogen not more than 0.01, oxygen not more than 0.01, iron is the rest. Steel can additionally contain not more than 0.6 wt % of chrome, not more than 0.1 wt % of niobium, not more than 0.1 wt % of titanium, not more than 0.1 wt % of zirconium and not more than 0.01 wt % of calcium. Content of steel corresponds to conditions: 12V + 1 - Mo ≥ 0 and Mo - (Cr + Mn) ≥ 0, where chemical element signs correspond to content of these elements in percentage by wt.

EFFECT: increased resistance against sulfide cracking.

9 cl, 2 dwg, 2 tbl