METHOD OF PRODUCTION OF BAR FROM MEDIUM-CARBON STEEL Russian patent published in 2006 - IPC C21D8/06 C22C38/12 C21C5/04 

FIELD: metallurgy; production of round calibrated bars from medium-carbon steel of high machinability for manufacture of shock absorber rods.

SUBSTANCE: proposed method includes making steel in electric-arc furnace, off-furnace treatment, micro-alloying with sulfur, continuous teeming at protection of jet with argon, hot rolling of continuously cast billet making use of mechanical heat treatment modes, hot calibration and winding merchant shape in bundles, unwinding bars, cutting and straightening bars. Steel contains the following components, mass-%: carbon, 0.42-0.50; manganese, 0.50-0.80; silicon, 0.17-0.37; sulfur, 0.020-0.040; phosphorus, 0.001-0.030; aluminum, 0.03-0.05; calcium, 0.0010.010; oxygen, 0.001-0.015; chromium, no more than 0.25%; nickel, up to 0.35%; copper, no more than 0.25%; molybdenum, no more than 0.10%; arsenic, no more than 0.08%; nitrogen, no more than 0.015%. The remainder being iron and unavoidable admixtures. Ratio of oxygen and calcium content is determined by the following ratio: oxygen/calcium =1-4.5 and calcium-sulfur ≥0.065. At tapping from melting unit, metal is subjected to deep deoxidation, alloying with silicon, manganese, chromium etc. After bringing the chemical composition of metal to specified level pertaining to all elements, but for aluminum and sulfur, metal and slag are subjected to repeated oxidation with gaseous oxygen or oxidized pellets. Then aluminum is added followed by treatment with calcium and alloying with sulfur.

EFFECT: enhanced conditions for machining articles made from this steel; improved ductility and toughness characteristics of steel.

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