Kinetics of decarburization of iron-chromium melts in highly oxidizing atmosphere
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DECARBURIZATION
is one of the m o s t i m p o r t a n t r e a c t i o n s and the p r o g r e s s of the s t e e l m a k i n g t e c h nique can be said as the h i s t o r y of d e c a r b u r i z a t i o n r e action i t s e l f . T h e r e f o r e , if the m e c h a n i s m of d e c a r b u r i z a t i o n p r o c e s s is m o r e c o m p l e t e l y u n d e r s t o o d it should be p o s s i b l e to i m p r o v e on the c o n t r o l and t h e r e by the e f f i c i e n c y and e c o n o m y of s t e e l m a k i n g . The k i n e t i c s of d e c a r b u r i z a t i o n of m o l t e n F e - C m e l t s have b e e n studied by m a n y i n v e s t i g a t o r s u s i n g v a r i o u s oxidizing a g e n t s and e x p e r i m e n t a l p r o c e d u r e s . Broadly, t h e r e a r e two s c h o o l s of opinion. F u j i et aI, Mori e t al, z P a d e r i n and Philippov 3 See and W a r n e r 4 e t c have c o n cluded that the r a t e is c o n t r o l l e d by g a s e o u s diffusion. On the c o n t r a r y , Swisher and T u r k d o g a n , s Ghosh and Sen, 6 Medvedevskikh e t a l ~ e t c have s u g g e s t e d a c h e m ical r e a c t i o n c o n t r o l l e d m e c h a n i s m . R e c e n t l y t h e r e has been a m a j o r b r e a k t h r o u g h in the m a n u f a c t u r i n g p r o c e s s of s t a i n l e s s s t e e l by AOD (Argon-Oxygen-Decarburization) process. Stainless steel can now be p r o d u c e d without any addition of high cost low c a r b o n F e - C r , f r o m the cheap s o u r c e s of c h r o m i um i . e . high c a r b o n F e - C r and s t a i n l e s s s t e e l s c r a p . In AOD p r o c e s s a high c a r b o n F e - C r m e l t is p r e f e r e n t i a l l y d e c a r b u r i z e d to a v e r y low c a r b o n by a r g o n oxygen gas m i x t u r e . In this r e s p e c t F e - C r - C s y s t e m p r e s e n t an e x c e l l e n t s y s t e m for the d e c a r b u r i z a t i o n study. In the p r e s e n t i n v e s t i g a t i o n , F e - C r - C m e l t s have oxidized by o x y g e n - n i t r o g e n gas m i x t u r e s . The effects of v a r i a b l e s such as p a r t i a l p r e s s u r e of oxygen, flowr a t e of gas m i x t u r e , a m o u n t of m e l t and t e m p e r a t u r e w e r e studied and a r e a c t i o n m e c h a n i s m has been p r o posed for the c a r b o n oxidation r e a c t i o n .
SUSHANTA KUMARDEY, formerly a graduate student of IIT, Kharagpur, is now with the BHEL, Bhopal, India. DHIRENDRA NATH GHOSH is Assistant Professor, IIT, Kharagpur, W.B. India. Manuscript submitted February 19, 1975. METALLURGICALTRANSACTIONSB
E X P E R I M E N T A L S E T - U P AND PROCEDURE The e x p e r i m e n t a l s e t up has b e e n d i s c u s s e d in d e t a i l e l s e w h e r e . 6 In the p r e s e n t i n v e s t i g a t i o n 200 g of F e C r - C m e l t w e r e p r e p a r e d in a f r e s h l y p r e p a r e d m a g n e s i t e c r u c i b l e in the g r a p h i t e r e s i s t a n c e f u r n a c e , u n der a r g o n a t m o s p h e r e . The s t a r t i n g c
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