Dissolution and Transport Phenomena of Deoxidizing Elements into Quiescent Molten Iron

Abstract

This work was carried out to obtain the knowledge of dissolution and the transport phenomena of deoxidizing elements into quiescent liquid iron.
Deoxidizers were added as block state or as liquid state on the surface of liquid iron melted in a tammann furnace. Changes of the temperature near the surface of the liquid iron were measured with thermocouples. After a predetermined holding time in the furnace, each heat was rapidly quenched into water. Concentration contours of deoxidizing elements were obtained on the surface by XMA point analyses. The results obtained are summarised as follows.
(1) When deoxidizer was added as liquid state, the deoxidizing elements were transferred into liquid iron by diffusion. The diffusion co-efficient of aluminum in liquid iron was obtained as 1.12×10^-4 cm²/sec.
(2) When deoxidizer was added as block state, the temperature near the surface went down. Owing to this temperature-drop, convection in the liquid iron occurred and deoxidizing elements were transferred with convection. This convection in the case of solid aluminum with dense and tight oxide film was stronger than that of silicon without a tight oxide film.
(3) When aluminum was transferred with convection, it produced high concentration regions. These regions floated up without reaction and diffusion. Owing to this phenomena, the yield of aluminum was scattered.