Development of improved cube-on-edge texture from strand cast 3pct silicon-iron
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UNTIL recently, regular grain oriented 3 pct siliconi r o n for t r a n s f o r m e r a p p l i c a t i o n s was m a d e e x c l u s i v e l y f r o m ingots. U s u a l l y , the ingots a r e f i r s t r o l l e d into s l a b s about 15 c m thick. The t e c h n o l o g y u s e d b y m o s t p r o d u c e r s w o r l d wide is to r e h e a t s l a b s f r o m ingots to t e m p e r a t u r e s n e a r 1400~ p r i o r to hot r o l l i n g . Other p r o d u c e r s h a v e a d o p t e d a p r a c t i c e of r e h e a t i n g ingots to s i m i l a r l y high t e m p e r a t u r e s p r i o r to hot r o l l i n g d i r e c t l y into s t r i p . By e i t h e r p r a c t i c e , r e h e a t i n g to t h e s e e x c e e d i n g l y high t e m p e r a t u r e s is n e c e s s a r y to a s s u r e s o l u t i o n of m a n g a n e s e s u l f i d e s in the s l a b p r i o r to hot r o l l i n g . D u r i n g hot r o l l i n g , the m e t a l is c o o l e d r e l a t i v e l y q u i c k l y , r e a c h i n g a t e m p e r a t u r e b e l o w 700~ within l e s s than 4 min. The r a p i d c o o l i n g c a u s e s the s u l f i d e s to p r e c i p i t a t e into m y r i a d s of p a r t i c l e s about 0.07 ;zm in d i a m . The MnS p a r t i c l e s i n h i b i t p r i m a r y g r a i n g r o w t h and p r o m o t e s e c o n d a r y r e c r y s t a l l i z a t i o n d u r i n g the final a n n e a l n e a r 1200~ which d e v e l o p s the the c u b e - o n - e d g e t e x t u r e . P r o v i s i o n of a s u i t a b l e i n h i b i t o r , such a s MnS, is an e s s e n t i a l condition for d e v e l o p m e n t of c u b e - o n - e d g e t e x t u r e a s was shown b y May and T u r n b u l l in t h e i r e x c e l l e n t s t u d y p u b l i s h e d in 1958.1 A s e c o n d n e c e s s a r y condition i s the p r o v i s i o n of a s u i t a b l e p r i m a r y r e c r y s t a l l i z e d s t r u c t u r e containing a c o m p o n e n t of g r a i n s with {110} (001) to s e r v e a s n u c l e i f o r the p a r t i c l e i n h i b i t e d s e c o n d a r y r e c r y s t a l l i z a t i o n , z* *Muchworkhas been done by numerousinvestigatorsOildeformationand recrystallizationtexturesin 3 pct silicon-ironespeciallyfor singlecrystals.The referenceciteddemonstratedthe needfor (110) primaryrecrystallized componentsof texture to obtain {110) texture after particleinhibited secondaryrecrystallizationin polycrystallinematerial. Conventional p r o c e d u r e s f o r r e g u l a r g r a i n o r i e n t e d s i l i c o n - i r o n involve p r o c e s s i n g hot r o l l e d c o i l s in two s t a g e s of cold r e d u c t i o n with an i n t e r m e d i a t e s t r i p a n n e a l . A f t e r the s e c o n d cold r o l l i n g r e d u c t i o n of about 50 p c t to f i n a l t h i c k n e s s , the m a t e r i a l i s s t r i p a n n e a l e d in wet h y d r o g e n to r e m o v e c a r b o n . D u r i n g d e carburization, primary recrystallizafion takes place. The final c u b e - o n - e d g e t e x t u r e is d e v e l o p e d
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