A Parametric Study of the Vacuum Arc Remelting (VAR) Process: Effects of Arc Radius, Side-Arcing, and Gas Cooling

The vacuum arc remelting (VAR) process is widely employed for purifying titanium-based alloys. This study aims to investigate the effects of various parameters on the solidification behavior of a Ti-6Al-4V VAR ingot. A numerical model is developed to analyze critical factors such as arc mode (diffusive or constricted), the extent of side-arcing, and gas cooling at the mold–ingot interface. The modeling incorporates the electromagnetic and thermal fields throughout the entire system including the electrode, vacuum plasma, ingot, and mold, enabling a comprehensive analysis of the flow field within the molten pool and the solidification profile. The results indicate that increasing the arc radius leads to a decrease in the depth of the molten pool, while reducing side-arcing increases this depth. Additionally, implementing gas cooling positively impacts the internal quality of the ingot, achieving a shallow molten pool depth without adversely affecting the hydrodynamics of the molten pool. Ultimately, the simulation results are validated against experimental data, highlighting the model's effectiveness in optimizing the VAR process.