CAST IRON, METHOD FOR PRODUCING THE SAME AND METHOD FOR THERMAL PROCESSING OF INGOTS CAST FROM THE SAME Russian patent published in 2006 - IPC C21C1/10 C21D5/00 

FIELD: metallurgy, in particular, production of high-strength cast irons with globular graphite for manufacture of high quality cast products.

SUBSTANCE: cast iron contains, wt%: carbon 3.23-4.08; silicon 2.76-3.89; manganese 0.20-0.47; molybdenum 0.15-0.48; aluminum 0.02-0.08; magnesium 0.02-0.05; barium 0.03-0.10; calcium 0.008-0.018; rare-earth metals 0.02-0.06; iron and admixtures the balance. Method involves melting cast iron in induction furnaces. In case of modifications, cast iron grid is used for overloading modified mixture containing, wt%: silicobarium 9.0-10.5; fluorspar 12-15; master alloy the balance. Master alloy contains, wt%: silicon 45-55; magnesium 6-9; calcium 3-7; rare-earth metals 3-8; aluminum 1-3; iron the balance. Total amount of mixture is 2.8-3.5% by weight of cast iron. Weight of grid is 1.5-2% by weight of cast iron. Method for thermal processing of ingots involves providing homogenizing annealing at temperature of 950-1000 C for 3-5 hours and ferritizing annealing by cooling in furnace to temperature of 780-720 C; holding at such temperature for 2.5-3 hours, followed by gradual cooling in furnace to temperature of 650-600 C; providing quick cooling in air or in water to room temperature and artificial aging by heating to temperature of 350-420 C, followed by holding for 2-3 hours.

EFFECT: increased plasticity, impact toughness and strength of products manufactured from cast iron of such composition.

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