Effect of alloying and processing on the subgrain-strength relationship in aluminum conductor alloys
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I n a r e c e n t p u b l i c a t i o n by the a u t h o r s , ~ t h e f l o w strengths o f t h r e e a l u m i n u m conductor a l l o y s were examined and correlated with microstructures prod u c e d by w i r e d r a w i n g r o d s t o c k t o l a r g e s t r a i n s ( ~ 2 . 6 t o 5.9) a n d a n n e a l i n g . F o r H 1 a n d H 2 t e m p e r s , *
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*Aluminum Association designations for process condition where the final step involves strain hardenittg or partial annealing forHI andH 2 , respectively. a P e r c h type relationship w a s obtained with the flow strength proportional to the i n v e r s e of the subgrain s i z e a c c o r d i n g t o o = a n + k L -~. It w a s f u r t h e r d e t e r m i n e d that the strength coefficient k (slope) of s u c h p l o t s i s a f f e c t e d by t h e t y p e o f a l l o y i n g e l e m e n t s even though t h e t o t a l alloying additions were o f t h e o r d e r of 1 p c t . T h i s w o r k h a s b e e n e x t e n d e d t o i n c l u d e o t h e r a l u m i n u m conductor alloys and p r o c e s s conditions. The p r e s e n t r e s u l t s demonstrate that the composition and initial rod condition have a significant effect o n t h e s u b s e q u e n t strength-subgrain relations h i p i n d r a w n w i r e . F u r t h e r v a r i a t i o n s in the t h e r m a l - m e c h a n i c a l p r o c e s s i n g f r o m r o d t o wire r e s u l t in a c o m m o n r a t e of s u b g r a i n s i z e s t r e n g t h e n i n g f o r a g i v e n alloy. S e v e n ,alloys i n v o l v i n g two s t a r t i n g r o d conditions and five thermal-mechanical p r o c e s s e s for d r a w i n g f r o m r o d t o wire were i n v e s t i g a t e d as i d e n t i f i e d in T a b l e I. T h e wire d r a w i n g p r o c e s s e s a r e designated f o r c o n v e n i e n c e a s T y p e s I t h r o u g h V a n d a l s o by the more g e n e r a l corresponding A l u m i n u m Association t e m p e r designation. T h e supply r o d ( 9 . 5 3 m m d i a m ) w a s e i t h e r c o n v e n t i o n a l l y c a s t a n d hot r o l l e d o r p r o d u c e d by a n i n t e g r a t e d c o n t i n u o u s c a s t r o l l i n g o p e r a tiort. 2 In e a c h c a s e t h e r o i l i n g o p e r a t i o n s w e r e hot and t h e f i n a l microstructures contained subgrairts characteristic of elevated temperature dynamic r e c o v e r y . O n e lot o f t h e E C a l u m i n u m r o d w a s g i v e n a f u l l r e c r y s t a l l i z a t i o n a n n e a l o f 723 K f o r 3 h p r i o r t o d r a w i n g . All o t h e r r o d l o t s were p r o c e s s e d f r o m the as-hot-rolled rod condition. P o s s i b l e homogenizat i o n e f f e c t s of t h e r e c r y s t a l l i z a t i o n a n n e a l a r e r e c o g n i z e d but w e r e n o t p u r s u e d i n t h i s s t u d y . T h e five thermal-mechanicat p r
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