Effects of Cu, Sn and W on the rate of nitrogen dissociation on the surface of molten iron

Abstract

The effects of Cu, Sn and W on the rate of nitrogen dissociation on the surface of molten iron have been investigated at 1 973 K by an isotope exchange method. The rate constant of nitrogen dissociation increases with increasing the content of W. On the other hand, the rate constant decreases with increasing the Cu and Sn contents. These effects of the alloying elements on the rate of nitrogen dissociation depend on the affinity of the solute element with nitrogen in molten iron. The elements which have stronger affinity with nitrogen than iron have a stronger effect of enhancing the nitrogen dissociation rate, and those which have stronger repulsive force against nitrogen have a stronger effect of retarding the nitrogen dissociation. The effect of the alloying elements on the rate of nitrogen dissociation is investigated based on a model proposed from the analysis on the basis of surface concentration of the solute. This model can reasonably represent the variation of the rate constant of nitrogen dissociation with the W content. © 2006 ISIJ.