Development of a New Magnetic Stirring Facility and Efficient Method for Refinement of Solidified Grain Structure

This work aimed to develop an efficient stirring facility and method with magnetic induction. Because the stirring by Rotation Magnetic Field (RMF) often produces strong macrosegregation, the Traveling Magnetic Field (TMF) was chosen for the stirring. The construction of this TMF twin-inductor is significantly different from the traditional magnetic stirrers, and it has a closed magnetic circuit. Three different magnetic fields can be produced with the developed twin-inductor to investigate the stirring effect. The inductor develops strong shearing stress at the flow perpendicular to the solidification front by flowing a part of metallic-melt layers touching each other in a direction opposite. The TMF twin inductor was combined with a solidification facility for the unidirectional solidification of different alloys.

The effect on the grain structure of the three different magnetic fields was compared using Al-7%Si-1% and Al-10%Si-0,2%Fe alloys. It has demonstrated that the most efficient mixing occurs when the magnetic fields in the two inductors move opposite each other.