EFFECT OF SURFACE-ACTIVE ELEMENTS ON NITROGEN REACTION WITH IRON MELTS

Experimental results of denitrogenation of pure iron melts were expres sed as a first or second order reaction, respectively. It was conclude d that, at [O] and [S] contents in the range 80-800 ppm, both diffusio n in the liquid and interfacial reaction control nitrogen transfer. A mixed control model is presented where the two rate controlling steps are involved. The mass transfer rate constants beta(c) and beta(I) wer e used to describe the nitrogen reaction. It was found that the coeffi cient beta(I) is influenced by surface active elements, mainly oxygen and sulphur. Finally, an overall reaction coefficient beta(ov) was eva luated as a function of the coefficients beta(c) and beta(I) and of th e nitrogen content in the iron melt. (C) 1995 The Institute of Materia ls. Manuscript received 27 December 1994.