Impact of Electromagnetic Stirring on Grain Structure of Electroslag Remelting Ingot

Abstract

A transient, two-dimensional axisymmetric model was developed to understand the effect of the electromagnetic stirring (EMS) on the grain morphology of the electroslag remelting ingot. The cellular automaton-finite element technique was employed to describe the nucleation and growth of the grain. The Joule heating and Lorentz force created by the current of the furnace, as well as the Lorentz force induced by the EMS device, are included. The effect of the EMS current on the grain structure was investigated using the model. A reasonable agreement between the experiment and simulation was obtained. The growth direction of the upper grain without the EMS is approximately 45° with respect to the vertical axis, while changes to the radial were caused by EMS. The grain was considerably refined by the EMS, and the average area of the grain decreased from 9.381 × 10−7 m2 to 6.781 × 10−7 m2 with the current of the EMS ranging from 0 A to 500 A. Both the local solidification time and second dendrite arm spacing decreased with the increasing stirring intensity. The metal pool depth, however, increased with the EMS, which definitely contributed to the macrosegregation formation. The upper ingot with EMS was darker than that without EMS in the experiment. The EMS technique should be used with caution.