CARBON LOW-ALLOY STEEL FOR ELECTRICALLY WELDED TUBES OF HIGHER CORROSION RESISTANCE Russian patent published in 2003 - IPC

FIELD: metallurgy; making carbon low-alloy steel for electrically welded tubes of higher corrosion resistance; erection of pipe lines transporting corrosive media, aqueous media in particular containing chlorine ions, hydrogen sulfide , carbon dioxide, mechanical admixtures and other components. SUBSTANCE: steel contains the following components, mas.%: carbon, 0.05-0.25; manganese, 0.20-1.70; silicon, 0.20-0.80; chromium, 0.01-1.00; nickel, 0.01-0.60; copper, 0.01-0.50; phosphorus, not exceeding 0.035; sulfur, not exceeding 0.025; aluminum, 0.01-0/06; iron and unavoidable admixtures, the balance. Content of sulfur and manganese corresponds to the following ratio: (Mn): (S) < 0.015, where (Mn) and (S) is content of manganese and sulfur, respectively. Density of corrosive non-metallic inclusions in steel does not exceed five in cu mm. Steel may additionally contain calcium in the amount of 0.0001-0.008%. Steel contains free ferrite at grain number no less than 8. EFFECT: enhanced corrosion resistance, strength and toughness at retained weldability and low cost. 3 cl, 1 tbl, 4 ex