Aluminum volatilization and inclusion removal in the electron beam cold hearth melting of Ti alloys

The electron beam cold hearth melting (EBCHM) process has emerged as either an alternative or a complement to vacuum are remelting, since it is capabl e of enhancing the elimination of hard-alpha inclusions by dissolution or s edimentation. The present article describes the use of a mathematical model to simulate the electron beam melting of titanium in a cold hearth. The ma thematical model is based on the numerical solution of the coupled momentum , solute, and heat transport equations in a transient regime for a three di mension geometry. The model calculates the velocity, turbulence intensity, temperature, and alloy composition in the liquid and the solid phases. The calculation provides the overall heat balance and the volatilization of met allic elements such as aluminum. ii postprocessor numerical tool simulates also the behavior of a hard-alpha inclusion during melting (trajectory and kinetics of dissolution). In order to demonstrate the usefulness of this mo del, the authors examine the influence of the casting rate and of the beam scanning frequency on the volatilization of aluminum and on the capacity of the process to remove hard-alpha defects.