COLD STRENGTH STEEL Russian patent published in 2002 - IPC

FIELD: metallurgy. SUBSTANCE: invention proposes cold strength steel comprising components taken in the following ratio, wt.%: carbon, 0.07-0.11; silicon, 0.2-0.4; manganese, 0.9-1.7; niobium, 0.025-0.05; nickel, 0.6-1.2; copper, 0.3-0.65; aluminum, 0.02-0.06; calcium, 0.005-0.03; sulfur, 0.001-0.015; iron, the balance. The content ratio of calcium to sulfur must be equal 2, not less, and an index of resistance to cracks in welding calculated by formula: P_rc = C + Si/30 + (Mn + Cu)/20 + Ni/60 + Nb/10 must be equal 0.23%, not above. The developed steel shows cold strength at temperatures up to 60 C and high resistance to layered ruptures by sheet thickness and retains the level of strength properties and welding ability in sections below 70 mm. The proposed steel relates to composites of constructional low-alloy steels used for making large-sized constructions, for example, hull ships, equipment for sea drilling platforms, vessels working under pressure and others devices working at decreased temperatures (up to 50 C) and under conditions of corrosive media of sea water type. EFFECT: improved quality and properties of steel. 1 dwg, 2 tbl