Thermomechanical working of Astroloy
- PDF / 1,753,669 Bytes
- 5 Pages / 612 x 792 pts (letter) Page_size
- 15 Downloads / 202 Views
A s t r o l o y was w a r m r o l l e d at t e m p e r a t u r e s b e t w e e n 1450 ~ and 1800~ and d i r e c t l y aged in the t e m p e r a t u r e range f r o m 1300 ~ to 1600~ Room t e m p e r a t u r e t e n s i l e s t r e n g t h s of 250 ksi and 0.2 pct y i e l d s t r e n g t h s of 200 ksi were obtained by s u b j e c t i n g the alloy to a 20 pct r e d u c t i o n at 1550~ followed d i r e c t l y by an 8 - h r aging t r e a t m e n t at 1600~ The t e n s i l e p r o p e r t i e s of the t h e r m o m e c h a n i c a l l y t r e a t e d m a t e r i a l r e m a i n e d s u p e r i o r to those of n o r m a l l y heat t r e a t e d a s t r o l o y up to test t e m p e r a t u r e s of 1800~ The w a r m working p r i m a r i l y s e r v e d to refine both the y' p r e c i p i t a t e and the g r a i n b o u n d a r y c a r b i d e s . P r e l i m i n a r y s t r e s s r u p t u r e t e s t s have indicated that the r e s u l t i n g t h e r m o m e c h a n i c a l l y t r e a t e d m a t e r i a l is m a r k e d l y i n f e r i o r to the n o r m a l l y heat t r e a t e d alloy when c o m p a r e d on the b a s i s of long time p r o p e r t i e s .
e n made increase N U Ma t t e mEp t s have R b eO U to S the s t r e n g t h of h i g h - t e m p e r a t u r e n i c k e l - b a s e a l l o y s . Changes in c o m p o s i t i o n , g r a i n morphology, and the d i s t r i b u t i o n of m i c r o s t r u c t u r a l c o n s t i t u e n t s have b e e n studied; and r e c e n t l y , it was p o s t u l a t e d that c o n t r o l of the defect density p r e s e n t d u r i n g p r o c e s s i n g could a l t e r the r e s p o n s e of these complex a l l o y s and r e s u l t in additional s t r e n g t h i m p r o v e m e n t s . 1,2 The p r e s e n t work was involved in the study of p r o p e r t y changes provided by the d i r e c t w a r m working and s u b s e q u e n t aging of Astroloy. The c o m p o s i t i o n of this n i c k e l - b a s e s u p e r a l t o y 3 i s given in T a b l e I.* P r e v i o u s *Thenormalheat treatingcyclefor thismaterialconsistsof: a 89hr solution treatmentat 2150~ (oilquench),a 4 hr stabilizationand primaryagingtreatment at 1975~ quench),a 24 hr agingtreatmentat 1550~ (air cooled),and a final 16 hr agingtreatmentat 1400~ w o r k e r s a have e s t a b l i s h e d that t h e r m o m e c h a n i c a l t r e a t m e n t s can m a r k e d l y a l t e r the p r e c i p i t a t e m o r phologies in a s i m i l a r alloy. The degree and n a t u r e of the change depends m a i n l y on the t e m p e r a t u r e at which the m a t e r i a l u n d e r g o e s d e f o r m a t i o n . Our e v a l u a t i o n s were made on the b a s i s of m e c h a n i cal test data. The p a r a m e t e r s of p r i m a r y i n t e r e s t were those which might provide an e n h a n c e m e n t of the m a t e r i a l ' s s t r e n g t h c h a r a c t e r i s t i c s , n a m e l y ; the working t e m p e r a t u r e , degree of d e f o r m a t i o n , and s u b s e quent heat t r e a t i n g p r o
Data Loading...
