Temper embrittlement of Ni-Cr steel by antimony:II. Effects of addition of titanium
- PDF / 2,017,183 Bytes
- 9 Pages / 612 x 792 pts (letter) Page_size
- 7 Downloads / 181 Views
Ni
Cr
C
Sb
Ti
O
3.5
1.7
0.003
0.065
0.1
0.012
It was v a c u u m induction m e l t e d at t h e G e n e r a l E l e c t r i c R e s e a r c h and D e v e l o p m e n t C e n t e r f r o m e l e c t r o l y t i c i r o n and high p u r i t y a l l o y i n g e l e m e n t s . The 4.5 kg ingot w a s hot f o r g e d , cold s w a g e d , and m a c h i n e d into c y l i n d r i c a l b a r s 0.64 cm d i a m by 6.4 cm, long. A u s t e n i t i z i n g t r e a t m e n t s w e r e c a r r i e d out at 1200~ in f u s e d q u a r t z c a p s u l e s e v a c u a t e d to ~10 -s T o r r and w e r e t e r m i n a t e d by quenching into i c e d b r i n e . S u b s e quent h e a t t r e a t m e n t s w e r e p e r f o r m e d in e v a c u a t e d V y c o r c a p s u l e s ; they involved: 1) t e m p e r i n g at 625~ for 1 h (the Q + T condition) f o l l o w e d by s t e p cooling o r i s o t h e r m a l aging in the r a n g e 450 to 560~ (The s t a n d a r d s'6 s t e p cooling t r e a t m e n t w a s u s e d , but was i n t e r r u p t e d a f t e r s u c c e s s i v e s t e p s , a s in P a r t I), o r 2) r e c r y s t a l l i z i n g at 675~ f o r 100 h (the Q + R condition) followed by s t e p cooling o r i s o t h e r m a l aging, o r 3) r e c r y s t a l l i z i n g at 675~ for 100 h d i r e c t l y a f t e r cold s w a g i n g and without the a u s t e n i t i z a t i o n t r e a t m e n t (giving the S + R condition). Notched-bar testing, optical metallography, fractog r a p h y with a s c a n n i n g e l e c t r o n m i c r o s c o p e (SEM), and AES w e r e c a r r i e d out a s d e s c r i b e d in P a r t I. M e chanical test specimens were circumferentially notched 1/4 in. (6.4 m m ) d i a m b a r s t e s t e d in slow c a n t i l e v e r b e n d i n g . The a r e a u n d e r e a c h l o a d - d e f l e c tion c u r v e w a s m e a s u r e d , and the m e a s u r e of e m b r i t t l e m e n t w a s the " t r a n s i t i o n t e m p e r a t u r e " at a f r a c t u r e e n e r g y of 2 f t - l b (2.7 J ) . T h e AES r e s u l t s a r e e x p r e s s e d in the following w a y s : N o r m a l i z e d A u g e r p e a k h e i g h t - t h e p e a k height of the e l e m e n t in q u e s t i o n i s d i v i d e d by the height of the F e p e a k at 703 eV. W e i g h t e d A u g e r p e a k h e i g h t - t h e n o r m a l i z e d p e a k height i s w e i g h t e d by a s i m p l e r u l e - o f - m i x t u r e s Ref. 1 in c a s e s w h e r e the f r a c t u r e is not c o m p l e t e l y i n t e r g r a n u l a r . A t . pct of a given e l e m e n t in t h e g r a i n b o u n d a r y r e g i o n - t h e w e i g h t e d p e a k height i s c o m p a r e d with a c a l i b r a t i o n c u r v e o b t a i n e d f r o m a s e r i e s of F e - b a s e d b i n a r y a l l o y s . T h e AES s p e c i m e n s w e r e f r a c t u r e d in u l t r a high v a c u u m at ~ - 90~ which was the l o w e s t t e m p e r a t u r e a t t a i n a b l e with our f r a c t u r e stage. RESULTS E m b r i t t l e m e n t of S b - T i
Data Loading...
