METHOD OF PRODUCING HIGH-STRENGTH CAST IRON Russian patent published in 2016 - IPC C21C1/10 C22C37/04 

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy and can be used for producing high-strength cast iron, suitable for production of articles with high ultimate strength. Method comprises melting and alloying of cast iron in induction furnace, graphitizing and inoculating modification, filling the shape with modified cast iron, obtaining casting with its further removal after crystallization from the mold at temperature of 900-1,000 °C, replacing the castings in the furnace with temperature of 950-1,000 °C and holding in the furnace for 10-30 minutes, with further isothermal hardening at temperature 300-320 °C for 60 minutes and air cooling, said alloying is performed with aluminium, silicon, nickel, copper, molybdenum and manganese, graphitizing and inoculating modification is carried out in the ladle, castings are produced in metal form in form of metal mold, after holding in the furnace cast iron castings are is produced with globular graphite and austenite-bainitic structure of the following chemical composition, wt%: carbon 2.5-3.2; silicon 1.5-2.5; aluminium 7.2-9.0; manganese 0.7-0.75; magnesium 0.04-0.06; molybdenum 0.7-1.2; nickel 0.48-0.52; copper 0.49-0.52; sulphur 0.01-0.012; phosphorus 0.06-0.08; iron-the rest, isothermal hardening of the produced casting is carried out in pseudo-boiling disperse carborundum layer in the area of austenite-bainitic conversion.

EFFECT: invention allows enlarging the application area of high-strength cast iron with globular graphite and austenite-bainitic structure with ultimate strength of σ_B≥1,200 MPa by bainitic hardening from cast state without additional thermal treatment.

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