Ferronickel is alloy containing 4 +6% (Ni + Co), about 0.1% carbon (the rest Fe and impurities). Major brands FN4, FN6, smelt in the predominantly oretermic furnaces using oxidizer nickel ores (0,9 +1,0% Ni; 0.05-0.09% Co, about 20% Fe and others). Ferronickel used primarily for alloying of structural steels.