TO THE DEFINITION OF THERMOPHYSICAL PROPERTIES ALLOY Ti–10V–2Fe–3Al AT VAR
DOI:
https://doi.org/10.14529/met200204Keywords:
vacuum arc remelting, titanium alloys, liquid bath profiles, thermophysical properties, mathematical modeling, boundary conditions, liquid phase, inverse problem of thermal conductivityAbstract
To carry out mathematical modeling of solidification of ingots, it is necessary to know the temperature dependences of the thermophysical properties of the solidified alloy and the parameters of the boundary conditions included in the mathematical model. In the present work, two ingots of Ti–10V–2Fe–3Al alloy are smelted and their macrostructure was investigated. The coordinates of the solidification isotherm profiles were measured and, using the solution of the inverse heat conduction problem, some thermophysical characteristics of the liquid phase and the boundary conditions for vacuum arc remelting (VAR) were determined, the direct experimental measurement of which is very difficult. An iterative Maximux A Posteriori (MAP) algorithm, previously tested for other titanium-based alloys, is used to determine the unknown parameters of the mathematical model by solving the inverse heat conduction problem. The required (i.e. initially unknown) parameters for the mathematical model of the VAR process were: thermal conductivity and heat capacity at solidus and liquidus temperatures; сoefficient of heat transfer from ingot to mold and coefficients of relative contribution of heat removal by radiation for tray and mold. As the set parameters, the values of the thermal conductivity coefficient and specific heat capacity in the temperature range 20‒1300 °C from the JMatPro database were used, calculated for the specified chemical composition. The density, heat of phase transformation, dynamic viscosity, and electrical conductivity were taken from the literature on the Ti–10V–2Fe–3Al alloy.
The found parameter values allow us to describe satisfactorily the change in the profile of the liquid bath when the ingot is fusing in the VAR for different process conditions (the diameter of the mold and the arc current).
The results obtained in this work can be used for mathematical modeling of the process of solidification of ingots made of Ti–10V–2Fe–3Al alloy during vacuum arc remelting with other mold diameters and arc current.
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