Effect of hot rolling on the dendritic texture of directionally solidified steel ingots
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D i r e c t i o n a l l y solidified ingots of t h r e e c o m m e r c i a l s t e e l s - - A I S I 1010, F e - 3 . 4 pet Si, and Type 430 s t a i n l e s s s t e e l - - w e r e h o t - r o l l e d at 1850~ i n o r d e r to study the effect of hot d e f o r m a t i o n on the a s - c a s t d e n d r i t i c t e x t u r e . The s t r o n g d e n d r i t i c (100) o r i e n t a t i o n of both the F e - S i and Type 430 alloys was c o m p l e t e l y d e s t r o y e d by the heavy r e d u c t i o n s t y p i c a l of the c o m m e r c i a l hot r o l l i n g of ingots. The p r i m a r y effect of hot r o l l i n g is to e l i m i n a t e the t e x t u r e p r e s e n t in the ingot, and to c r e a t e c e r t a i n new t e x t u r e s . T h e s e new t e x t u r e s a r e in e v e r y c a s e weak. F o r exa m p l e , the AISI 1010 s t e e l , which had v e r y l i t t l e of the d e n d r i t i c (100) o r i e n t a t i o n in the ingot stage, has a c o m b i n a t i o n of two weak t e x t u r e s after hot r o l l i n g : (100) [011] and (110) [ h 0 ] . Likewise, with the o t h e r two m a t e r i a l s , which had a s t r o n g d e n d r i t i c (100) o r i e n t a t i o n i n the ingot stage, hot r o l l i n g r e s u l t e d i n weak t e x t u r e s : (110) [001] with a r o t a t i o n of this o r i e n t a t i o n of +45 deg about the [001] r o l l i n g d i r e c t i o n , followed by (110) [001] r o t a t e d +35 deg about the [i10] in the t r a n s v e r s e d i r e c t i o n .
C R Y S T A L L O G R A P H I C t e x t u r e s have been r e c o g n i z e d as an i m p o r t a n t p a r a m e t e r i n the o p t i m i z a t i o n of s h e e t s t e e l p r o p e r t i e s . F o r e x a m p l e , the c u b e - o n - f a c e o r i e n t a t i o n i m p a r t s d e s i r e d e l e c t r i c a l p r o p e r t i e s to s i l i c o n s h e e t s t e e l , 1 and the c u b e - o n - c o r n e r o r i e n t a t i o n i m p r o v e s the deep d r a w a b i l i t y of l o w - c a r b o n sheet s t e e l . 2 The d e v e l o p m e n t of these p r e f e r r e d o r i e n t a t i o n s is g e n e r a l l y brought about by m e a n s of p r o p e r m e c h a n ical d e f o r m a t i o n and heat t r e a t m e n t . R e c e n t a d v a n c e s in d i r e c t i o n a l s o l i d i f i c a t i o n in the ingot s t a g e have indicated that d i r e c t i o n a l s o l i d i f i c a t i o n might a l s 0 s e r v e as a method for developing p r e f e r r e d o r i e n t a t i o n s , p r o v i d e d that s u b s e q u e n t p r o c e s s i n g does not d e s t r o y such o r i e n t a t i o n s . F o r e x a m p l e , B a r r e t t has found that bcc m e t a l s , such as i r o n , solidify with a d e n d r i t i c (100) growth o r i e n t a t i o n . 3 C o m p l i c a t i o n s a r i s e i n that the a s - c a s t t e x t u r e of i r o n and l o w - a l l o y s t e e l is a l t e r e d due to s o l i d - s t a t e phase t r a n s f o r m a tions that o c c u r d u r i n g cooling. However, i n a s i n g l e phase alloy the (
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