METHOD OF THERMAL PROCESSING OF MOULDED PARTS FROM LOW-CARBON ALLOYED STEELS Russian patent published in 2017 - IPC C21D1/56 C21D1/78 B61F5/00 

FIELD: metallurgy.

SUBSTANCE: invention relates to the thermal treatment of moulded parts of railway rolling stock in the form of side frames of freight wagon carriages made of 20GL, 20GFL, 20GTL steels. To increase the fatigue strength of the part, reduce the formation of cracks and increase the durability, the cast piece is heated in the temperature range from Ac₃ before Ac₃+100°C, hold for 60-90 minutes, then move the part in the thermos into the quenching device, in which cooling is carried out in two stages. First, the surface of the part is intensively cooled from the temperature Ac₃ for 0.5 s at a speed of 890-1180°C/s to the temperature of the martensitic transformation (Mk) end by volumetric strangulation with a dispersed water-air mixture, and then with jets of water to a temperature of not more than 200°C for 8-10 minutes.

EFFECT: reduction of the cooling rate of the most loaded portions of the parts in operation 8-10 times compared with other parts of the product.

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