Experimental and Numerical Study of the Plasma Arc Melting of Titanium Alloys: Application to the Removal of High Density Inclusions (HDIs)

Titanium alloys are increasingly used in aeronautical applications, a sector that requires highly controlled materials. In particular, inclusion cleanliness is a necessary and mandatory condition for safe use in aeronautical components. During the production and processing of titanium alloys, inclusions are likely to appear, in particular high-density inclusions (HDIs) originate from refractory metals such as molybdenum or tungsten carbide. Plasma Arc Melting-Cold Hearth Remelting (PAMCHR) is one of the most effective recycling and refining process for titanium alloys. Firstly, this work reports the thermal modeling of the melting of raw materials in the melting crucible and a complete 3D numerical simulation of the thermo-hydrodynamic behavior of the metal flow in the PAMCHR furnace, based on the software Ansys-Fluent CFD V21.1. Simulation results are presented for a 100 kg/h melting test performed in a pilot furnace with a comparison between the measured and calculated pool profiles and residence time distributions that show satisfactory agreements. Additionally, a Lagrangian calculation of particle trajectories in the liquid metal pool is also performed and insemination of HDIs in the pilot furnace has been tested. Both numerical and experimental tests demonstrate the inclusion removal in the melting crucible.