METHOD FOR UNIDIRECTIONAL AND ACCELERATED HARDENING OF LARGE-SIZE THICK-WALLED CENTRIFUGAL CAST STEEL WORKPIECES Russian patent published in 2020 - IPC B22D13/00 

FIELD: foundry.

SUBSTANCE: invention relates to foundry production, in particular, to centrifugal casting and can be used in heavy, power, petrochemical, metallurgical and other machine building industries for production of large-size products for critical purposes. Fusible powdered flux is introduced on the surface of the liquid metal surface immediately after its pouring is completed into a rotating multilayer mold in amount of 2.5–3.0 kg per 1 m² of a free casting surface at accelerated and sequential movement of hardening front from its outer surface to inner one with average speed of not less than 0.002 m/min, which is provided with high intensity of heat transfer of rotated multilayer shape due to sprayer cooling with water, as well as heat-insulating coating of inner surface of mold with layer thickness of 0.003–0.005 m, consisting of mixture of quartz sand and zircon powder in ratio of 1:1, and maintaining the thickness of the gas gap, which is determined by the value of linear shrinkage of 1.3–1.5 % of casting at rotation frequency of said shape, which corresponds to gravity coefficient 201–220 on the outer surface of the casting.

EFFECT: invention enables to create conditions for accelerated and sequential hardening of metal with average speed of not less than 0_002 m/min, which facilitates formation of a homogeneous metal structure without segregation streamers, as well as to obtain a workpiece without shrinkage and segregation defects by introducing a low-melting powder flux onto the inner surface of the casting to prevent sinks and pores in the casting body.

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