Impact of a Transient and Asymmetrical Distribution of the Electric Arc on the Solidification Conditions of the Ingot in the VAR Process

Abstract

Vacuum Arc Remelting is an important method of processing reactive and refractory liquid metal alloys, including titanium and zirconium alloys. Recent measurements of the electric arc dynamics under the presence of a time-varying magnetic field during an industrial melt of a Ti64 alloy provided evidence of the existence of an ensemble arc motion. Such motion is responsible for transient and non-axisymmetric inputs of electric current and energy at the top surface of the remelted ingot. The present work is an attempt to evaluate, using a simplified numerical simulation approach, to what extent the solidification conditions of the VAR ingot and, consequently, the quality of the final product, may be affected by this phenomenon. The reported results indicate that, under the worst case conditions, the relative vanadium segregation in the solidified ingot can reach values as high as 12.5%.

Keywords

• vacuum arc remelting
• titanium alloy
• electric arc
• solidification