Variations in the average size and quantity of nonmetallic inclusions during oxidation and deoxidation of steel
- PDF / 495,041 Bytes
- 5 Pages / 612 x 792 pts (letter) Page_size
- 39 Downloads / 210 Views
T H E c o m m e r c i a l l y available steels usually contain a v a r i e t y o f nonmetallic inclusions such as oxides, nit r i d e s , o r s u l f i d e s . T h e o x i d e s a r e u s u a l l y the m o s t predominant and, therefore, have received a g r e a t e r a m o u n t o f a t t e n t i o n in t h e l i t e r a t u r e . T h e s e i n c l u s i o n s mostly c o m e f r o m t h e s t a b l e oxide particles w h i c h are f o r m e d and trapped d u r i n g the deoxidation of molten steel. T h e inclusions are known t o have significant inf l u e n c e on t h e m e c h a n i c a l p r o p e r t i e s of s t e e l . 1 In s o m e i n s t a n c e s , t h e i n c l u s i o n s m a y well s e r v e to e n h a n c e s e l e c t e d p r o p e r t i e s , w h i l e i n s o m e o t h e r s they m a y be e x t r e m e l y d e t r i m e n t a l . The p r e v a i l i n g e f f e c t is d e t e r m i n e d by the s i z e , s h a p e , q u a n t i t y , a n d the d i s t r i b u tion of t h e i n c l u s i o n s . D u r i n g o x i d a t i o n o r d e o x i d a t i o n r e a c t i o n s , the c h a n g e s i n the o x y g e n l e v e l of t h e b a t h a n d the n a t u r e o f the o x i d i z i n g o r r e d u c i n g a g e n t s s h o u l d d i r e c t l y a f f e c t the v a r i a t i o n s i n s o m e s e c o n d a r y p a r a m e t e r s s u c h a s the a v e r a g e s i z e , the a v e r a g e n u m b e r p e r u n i t v o l u m e , a n d the v o l u m e f r a c t i o n of the i n c l u s i o n s . S o m e r e c e n t investigations have been d i r e c t e d at t h e k i n e t i c s of the f o r m a t i o n a n d the g r o w t h of the d e o x i d a tion p r o d u c t s , 2-4 a n d the e f f e c t i v e r e m o v a l of t h e s e n o n m e t a l l i c i n c l u s i o n s f r o m the m e t a l b a t h . s'6 In the literature, f e w s y s t e m a t i c s t u d i e s h a v e b e e n r e p o r t e d o n the v a r i a t i o n of the v a r i o u s s e c o n d a r y p a r a m e t e r s d u r i n g o x i d a t i o n a n d d e o x i d a t i o n of steel. S u c h s t u d i e s w o u l d not only d e s c r i b e the v a r i a t i o n of the o x y g e n l e v e l a n d the n a t u r e of the d e o x i d i z e r but m a y s e r v e a s i m p o r t a n t g u i d e l i n e s for a s s e s s i n g the q u a l i t y of s t e e l v i e w e d as a metal-oxide composite. In the p r e s e n t investigation, the v a r i a t i o n s in s e v eral s e c o n d a r y p a r a m e t e r s have been studied s y s t e m atically d u r i n g the o x i d a t i o n of s t e e l b y d i r e c t o x y g e n injection and deoxidation u s i n g v a r i o u s deoxidizers s u c h a s A 1 , Si, F e - S i (79 p c t S i ) , F e - M n (75 p c t Mn), F e - C r (75 p c t C r ) , a n d g r a p h i t e . T h e r e a c t i o n s h a v e b e e n c a r r i e d out in c o m m e r c i a l l y available g r a p h i t e c r u c i b l e s a t 1550°-~ 10°C u s i n g a n i n d u c t i o n f u r n a c e . G. K. BANDYOPADHYAY and H. S. RAY are Graduate Student and Assistan
Data Loading...
