SIMULATION OF TEMPERATURE FIELD AT THE MOLD SURFACE AND INSIDE THE CASTING AT HIGH-GRADIENT DIRECTIONAL SOLIDIFICATION PROCESS

In order to determine the thermal gradient in a single crystal ingots obtained using the directional solidification method on the UVNS-6 apparatus (Russian Scientific Research Institute of Aviation Materials, Moscow), the single crystal ingots of nickel-based superalloy VJM3 were made. The ingots were made using the liquid metal cooling (LMC) directional solidification method (DS) and without it (Bridgman–Stockbarger technique). The liquid Sn was used for a liquid metal cooling technique. To record the temperature during the ingots obtaining process we use a thermocouple placed on the ceramic mold surface. The directional solidification process of the nickel-based superalloy VJM3 ingots on the UVNS-6 apparatus was simulated using the ProCast software. The thermal properties of the VJM3 alloy, ceramic mold and the DS apparatus parts and the boundary conditions (interface heat transfer coefficient) were  found in the literature. There is a good agreement between the calculated and experimental values of the temperature distribution in a mold using the LMC and the Bridgman–Stockbarger technique. A simulation of the directional solidification in the ProCast software is suitable for predicting the thermal gradient on a solidification profile location, and the mushy zone width (a site of the dendritic structure formation). The calculated thermal gradient value in the ingot obtained using the Bridgman–Stockbarger technique is 36 °С/cm. The thermal gradient using the LMC method is 204 °С/cm, is six time higher, than if using the Bridgman–Stockbarger technique. Used thermal properties and boundary conditions can be applied for simulation of Ni-based superalloys blades casting process.

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