Enhancement of iron melting rate under the co-existence of graphite and wiistite

Abstract

Carburization and melting processes of solid Fe under the co-existence of graphite and wüstite has been investigated based on a confocal laser scanning microscope "in-situ" observation of the movement of the interface between Fe-C melt and solid Fe at 1 523 K. In the experiments, strong stirring flow at the surface of the Fe-C melt is observed. This flow is found to be Marangoni flow and is introduced by the surface tension gradient due to the difference of oxygen concentration between the Fe-C melt interface with graphite and solid iron. The velocity of Marangoni flow is measured from the moving velocities of bubbles at the molten Fe-C surface. The melting rate of Fe is analyzed by computational fluid flow simulations of the Fe-C melt. Based on these results, it is confirmed that the carburization and melting rate of solid Fe can be enhanced by allowing Fe-C melt to come into contact with wüstite and graphite simultaneously.