Some Consideration on the Mechanism of Deoxidation Reaction of Molten Steel

Abstract

The mechanism of deoxidation reation of molten steel was studied. Both macroscopic oxide inclusions in solid steel, which was enriched with oxygen and silicon added, were situated on boundary of cells. The result shows that all of inclusions found in solid steel are precipitated from melt during solidification of the steel, and that there are no suspended deoxidation products in melt. It was observed that deoxidation products were precipitated on the inner surface of crucible during holding in melt. In some case, the deoxidation products were dendritic. From above experimental results, the following conclusions were introduced.
(1) When adding deoxidant in molten steel was enriched with oxygen, dessolved oxygen and deoxidant would react rapidly to produce an oxide dissolved in monomolecule state, but. not to be grown to oxide particles.
(2) Dissolved monomolecular oxides in steel wonld diffuse to inersurface between melt and crucible, and form oxide phase only on the inner surface of crucible. Consequently oxygen content in steel should be decreased slowly.
Rate of oxygen drop after addition of silicon in iron melt enriched with oxygen was measured. The experimental results were consistent with theoretical result introduced by the above model of deoxidation reaction.