STEEL OF HIGHER RUSTPROOF QUALITIES AND ELECTRIC-WELDED PIPES MADE THEREOF Russian patent published in 2014 - IPC C22C38/48 

FIELD: metallurgy.

SUBSTANCE: proposed composition contains the following substances, in wt %: carbon - 0.03-0.08, manganese - 0.5-1.1, silicon - 0.01-0.5, chromium - 0.6-1.2, nickel - 0.05-0.3, copper - 0.05-0.3, phosphorus - not over 0.015, sulphur - not over 0.005, aluminium - 0.01-0.05, calcium - 0.0001-0.006, niobium - 0.01-0.05, iron and unavoidable impurities making the rest. This steel features ferrite-perlite structure with lamination not over 2 while maximum admissible density of corrosive non-metal inclusions (H_CANI) is defined subject to niobium content in steel according to: |H_CANI| ≤5.6-33·|Nb|, where |H_CANI| is absolute value of N_CANI density, inclusions/mm², |Nb| is absolute magnitude of niobium content, wt %. Calcium content in steel is defined by the following relation: |Ca|/|Al|≤0.24, where |Ca| is modulus of calcium content, wt %, |Al| is modulus of aluminium content, wt %.

EFFECT: higher corrosion resistance, anti-cracking resistance and local corrosion resistance, higher purity and manufacturability.

4 cl, 3 tbl, 1 ex