The Formation Mechanism of Inverse Segregation of Steel Ingots

Abstract

To understand the formation mechanism of inverse segreggation of steel ingots, thesolidification phenomenon of ammonium chloride-water solutions in glass molds were observed. Based on the observation, it is believed that the formation mechanism of the inverse segregation of steel ingots was due to trapping of the solute concentrated liquid between the solid shell and the equiaxed crystal zone, because the equiaxed crystals formed in the liquid ahead of the solid shell and beyond the solute concentrated zone.
It is also believed that the settling of crystals in the lower part of the equiaxed crystal-and-liquid mixture zone resulted in streak type inverted V shape tears filled with solute concentrated liquid in the zone. Furthermore, the negative segregation is believed to be formed by crystals which were carried from the advancing solid-liquid interface by the convection in the early stage of the solidification process.