METHOD OF MAKING CAST STEEL Russian patent published in 2003 - IPC

FIELD: making steels for manufacture of magnetic circuits of permanent electromagnets for muon detectors of high-energy beam accelerators. SUBSTANCE: proposed method includes smelting in steel-making unit, refining and correction of chemical composition and tapping in slabs by means of continuous tapping machine. Steel contains components at the following ratio, mass- %: carbon, 0.04-0.12; silicon, 0.04-0.30; manganese, 0.20-0.50; sulfur, no more than 0.025; phosphorus, no more than 0.050; chromium, no more than 0.10; copper, no more than 0.25; aluminum, no more than 0.028; nickel, no more than 1.0; nitrogen, 0.005-0.012 and the remainder being iron. Correction of chemical composition is performed as follows: content of carbon, silicon, manganese, aluminum and nitrogen is found from expression k = 9200-m)/810, where m is preset magnitude of relative magnetic permeability, then parameter k is determined which is maintained between 0.031 and 0.062; ratio of contents of carbon, silicon, manganese, aluminum and nitrogen are found from the following formula: k = 0.23 (C) + 0.10 (Si) + 0.05 (Mn) + 0.09 (Al) + 0.06 (N). Ratio of aluminum content to nitrogen does not exceed 5.0 and ratio of manganese to sulfur is no less than 20.0. Continuous tapping is performed at mass flow rate of steel found from the following formula: M= K a/b, where M is mass flow rate of molten steel, kg/s; K is flow rate coefficient equal to 2.8-5.0 kg/s; a is width of slab, m; temperature of surface is maintained between 700 and 850 C; then, slabs are cooled for 0.5-2.0 hours to temperature of 550-650 C and then for 30-50 hours to temperature of 50-70 C. Steel made according to this method has magnetic permeability of 158.2-167.0 at induction of 1.8 T. Ultimate strength of steel thus obtained is 310 Mpa at yield point of 189 Mpa. EFFECT: enhanced efficiency and reliability. 1 ex