National University of Science and Technologies “MISiS”, Moscow, Russia:

V. E. Bazhenov, Senior Lecturer of a Foundry Technologies and Material Art Working Department, e-mail: V.E.Bagenov@gmail.com
A. V. Petrova, Master's Student of a Foundry Technologies and Art Working Department
A. V. Koltygin, Assistant Professor of a Foundry Technologies and Material Art Working Department
Yu. V. Tselovalnik, Master's Student of a Foundry Technologies and Material Art Working Department

It is necessary to know the interface heat transfer coefficient (iHTC) between the casting and the mold for the simulation of casting filling and solidification processes in the casting simulation software systems. This study demonstrates the way we determined the heat transfer coefficient h between the cylindrical casting of 50–56 mm in diameter and 150 mm in height of the AZ91 magnesium alloy and no-bake mold on synthetic resin binder. The temperature field in the mold and the temperature of the alloy were determined using twelve thermocouples installed in the mold and mold cavity. Their temperature data were recorded when pouring, solidification and cooling of the casting. The ProCast software used for the simulation of filling and solidification of castings. Then the cooling curves were obtained for the points in the model corresponding to the position of thermocouples during the experimental casting. We used the thermal properties of the mold available in the literature and the thermal properties of the alloy calculated using the ProCast thermodynamic database. Simulation and recording of temperature measurements were carried out to 1500 s. To determine the heat transfer coefficient the error function was used. It indicates the difference between the experimental and calculated values of the temperature in the casting and mold. The value of heat transfer coefficient was set as temperature dependence. The value of the heat transfer coefficient in the range h_L = 600–1300 W/(m²·K) in every 100 W/(m²·K) was set above the liquidus temperature (610 ^оC) of the alloy. The heat transfer coefficient h_S = 500–700 W/(m²·K) was set below the solidus temperature of the alloy (415 ^оC). We tried to find a value of heat transfer coefficient at which the error function was minimized, and hence the difference between the calculated and experimental temperature field in the casting and mold has also been minimal. The obtained values of the heat transfer coefficient between the casting and mold are h_L = 1100 W/(m²·K) above the liquidus temperature and h_S = 600 W/(m²·K) below the solidus temperature. Such heat transfer coefficient values give the error function not more than 20 ^оC.

This work was carried out with the support of the Russian Federation President's Grant to the young scientists and post-graduate students, carrying out the prospective scientific investigations and developments on priority ways of modernization of russian economics (contest of 2016–2018).

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