Numerical Simulation of Inclusion Distribution in Vacuum Arc Remelting Ingot

The electronic scanning microscope is applied to analyze the inclusion distribution in the ingot middle part. It is observed that the large-size inclusions are mainly located at a distance of 1.6 mm from side surface. With the distance increasing, the area fraction, number density, and diameter of inclusion decrease clearly. As the inclusion is assumed as spherical, the melt flow, solidification, and particle redistribution are simulated by a coupled model. With the electric power applied, the electromagnetic force shows a maximum in the ingot edge part, which pushes liquid from the edge part to the inner part. The particle movement is both affected by fluid flow and particle buoyancy force. In the earlier remelting stage, fluid flow is dominated by electromagnetic force and it drives the particle moving from the inner top part to the ingot bottom, where it can be captured. As the liquid pool depth increases in the later stage, the thermal flow drives the particle moving along the solidification front. Due to particle buoyancy, the 50 mu m diameter particle floats up, and it is mainly located in the ingot side surface. For the 2 or 10 mu m particle, it still exists in the inner part.