A Numerical Study on the Influence of an Axial Magnetic Field (AMF) on Vacuum Arc Remelting (VAR) Process

A comprehensive numerical model is proposed to study the influence of an axial magnetic field (AMF) on the solidification behavior of a Titanium-based (Ti-6Al-4V) vacuum arc remelting (VAR) ingot. Both static and time-varying AMF are examined. The proposed 2D axisymmetric swirl model includes calculating electromagnetic and thermal fields in the entire system composed of the electrode, vacuum plasma, ingot, and mold. A combination of vector potential formulation and induction equation is proposed to model the electromagnetic field accurately. Calculations of the flow in the melt pool and solidification of the ingot are also carried out. All governing equations are presented in cylindrical coordinate. The presence of a weak AMF, such as the earth magnetic field, can dramatically influence the flow pattern in the melt pool. The Electro-vortex flow is predicted ignoring AMF or in the presence of a time-varying AMF. However, the flow pattern is Ekman pumping in the presence of a static AMF. The amount of side-arcing has no influence on the pool depth in the presence of an AMF. Modeling results are validated against experiments.

Automated summary

A comprehensive numerical model is proposed to study the influence of an axial magnetic field on the solidification behavior of a Titanium-based vacuum arc remelting ingot. The model considers electromagnetic and thermal fields, melt pool flow, and solidification process. Results show that a weak AMF can dramatically affect the flow pattern in the melt pool.