Effect of stress on microsegregation of hydrogen at elevated temperatures in titanium and Ti-8Al-1Mo-1V
- PDF / 1,728,940 Bytes
- 4 Pages / 569 x 813.28 pts Page_size
- 11 Downloads / 184 Views
Table I. Mechanical Properties of Pure Titanium and Ti~SAI-1Mo-IV Containing Hydrogen at Elevated Temperatures
Alloy Pure Ti Ti-8AI-IMo-IV
Hydrogen, At. Pct 0.81 0.81 0.48
Y.S., psi
U.S., psi
Temp,~
7430 12,900 84,400
11,280 16,540 105,770
600 450 600
Effect of Stress on Microsegregation of Hydrogen at Elevated Temperatures in Titanium and Ti-8A I-1Mo-IV T. L. MACKAY T H E d i s t r i b u t i o n of hydrogen u n d e r a v a r y i n g s t r e s s f i e l d in high p u r i t y titanium and an a-/3 t i t a n i u m alloy, T i - 8 A I - I M o - I V , was studied in the t e m p e r a t u r e r a n g e 450 ~ to 600~ by an e l e c t r o n m i c r o a u t o r a d i o g r a p h y technique z High purity i o d i d e t i t a n i u m r o d , 99.995 pct p u r i t y , and fl f o r g e d T i - S A I - I M o - I V 2 w e r e used in t h e s e e x p e r i m e n t s . The t e n s i l e p r o p e r t i e s of p u r e t i t a n i u m c h a r g e d with 0.80 at. pct H w e r e m e a s u r e d at 450~ and 600~ T e n s i l e p r o p e r t i e s of T i - 8 A I - I M o - I V c h a r g e d with 0.50 at. pct H w e r e m e a s u r e d to 600~ The r e s u l t s a r e shown in T a b l e I. T o m e a s u r e the e f f e c t s of a s t r e s s field on the h y d r o g e n d i s t r i b u t i o n , i a ~- in. diam rod with a t a p e r e d g a g e s e c t i o n , 0.10 in. diam at c e n t e r , w a s e m p l o y e d . It i s p o s s i b l e to u s e t r i t i u m , the r a d i o i s o t o p e of hyd r o g e n , to show the d i s t r i b u t i o n of the contained hyd r o g e n . S p e c i m e n s w e r e c h a r g e d with t r i t i u m at 1350~ and s u b s e q u e n t l y w a t e r quenched. T h e s p e c i m e n s w e r e then held at the d e s i r e d t e s t t e m p e r a t u r e for 24 hr b e f o r e s t r e s s i n g . S p e c i m e n s w e r e s t r e s s e d at t e m p e r a t u r e for 200 h r at 80 pct of yield s t r e n g t h (0.2 pct Y.S.) and w a t e r quenched. F o l l o w i n g s t r e s s i n g , the s p e c i m e n s w e r e m a c h i n e d flat through the c e n t e r l i n e . A f t e r rough p o l i s h i n g through 600 g r i t SiC p a p e r , the s u r f a c e w a s e l e c t r o l y t i c a l l y p o l i s h e d at -40~ using the t e c h n i q u e f o r p r e p a r a t i o n of f o i l s for e l e c t r o n t r a n s m i s s i o n m i c r o s c o p y , s A final etch with K r o l l s r e a g e n t w a s n e c e s s a r y to show g r a i n b o u n d a r i e s c l e a r l y . The d i s t r i b u t i o n of p r e c i p i t a t e s and t r i t i u m in s o l i d s o l u tion in an u n s t r e s s e d s p e c i m e n with 0.75 at pct w a s m a d e following w a t e r quenching f r o m 600~ F i g . 1 is a m i c r o a u t o r a d i o g r a p h showing d i s t r i b u t i o n of h y d r i d e p r e c i p i t a t e s and t r i t i u m in s o l i d solution. An e x p o s u r e t i m e of 15 mill was u s e d f o r the n u c l e a r t r a c k e m u l s i o n . All of the fine p r e c i p i t a t e s w e r e a s s o c i a t e d with
Data Loading...
