METHOD OF PRODUCTION OF RAIL STEEL Russian patent published in 2005 - IPC

FIELD: metallurgy.

SUBSTANCE: proposed method includes charging scrap and lime into electric-arc furnace, melting the scrap, pouring molten cast iron, oxidizing carbon with gaseous oxygen, dephosphorization, flushing the oxidizing slag through foreplate followed by tapping the steel into ladle and adding slag-forming mixture and ferroalloys into ladle during tapping the steel. During tapping, furnace slag is cut-off and molten metal is left in furnace in the amount of 10-15% of melt. Then, slag-forming mixture is added to ladle. This mixture contains lime and fluorspar at ratio of (0.8-1.2) : (0.2-0.5) and flow rate of 10-17 kg/t of steel, as well as silicon and manganese-containing ferroalloys: up to 0.15% of silicon and up to 0.75% of manganese. Then, steel is treated on furnace-ladle unit by introducing manganese, silicon, carbon, vanadium and calcium to required concentration. Steel is subjected to blowing through bottom porous tuyere at flow rate up to 65 nm³/h at total amount of gaseous nitrogen not exceeding 20 nm³ to content of nitrogen of 0.020%. Final blowing is performed with argon at flow rate of up to 65 nm³/h.

EFFECT: reduction of contamination with non-metallic inclusions; improved properties of rail steel; reduced consumption of alloying and deoxidizing agents; reduced duration of melting process and electrodes; reduced power requirements.