METHOD FOR GRAPHITIZATION OF LOW-CARBON STEELS COMBINED WITH PRELIMINARY CEMENTATION IN THE TEMPERATURE OF POLYMORPHOUS TRANSFORMATION TEMPERATURES Russian patent published in 2019 - IPC C23C8/66 

FIELD: technological processes.

SUBSTANCE: invention relates to thermal and chemical-thermal treatment of steel parts, namely to processes of graphitization and heat treatment of materials by means of annealing in medium of carburizer. Method of graphitizing parts from low-carbon steels involves heating parts in medium of carburizer to temperature of 20–40 °C above Ac₃ point and holding at this temperature for 0.2–2.0 hours. Said heating and holding are performed to obtain an austenite structure and formation of the required carbonized layer depth, and then sublinging to the temperature of polymorphous transformation of Ar₃-Ar₁ with subsequent exposure at this temperature for 6.0–8.0 hours, at which final formation of the cemented layer and its graphitization to the required depth is carried out.

EFFECT: obtaining on the steel parts a surface graphitized layer of greater depth, cutting and simplifying the processing process.

1 cl, 5 dwg, 1 ex