Calculation of cell-size strengthening of wire-drawn iron
- PDF / 292,039 Bytes
- 3 Pages / 612 x 792 pts (letter) Page_size
- 12 Downloads / 280 Views
Test Temp, 25~ Yield Strength, UltimateStrength, 1 Pet e, psi psi Pet Elongation Normal Cast Liquid Quenched
12,750 23,000
Normal Cast Liqmd Quenched
28,000 37,000
18,800 26,200
n*
20 4
0.18 0.16
31 ~5
O.17 0.20
Test Temp,- 196~C 46,100 41,500
*a = Ke n
the f o r c e to d r i v e the liquid a l l o y into the c h i l l e d c o p p e r m o l d was e f f e c t e d by a t m o s p h e r i c p r e s s u r e by m e a n s of e v a c u a t i n g the m o l d . The p r e s e n t a p p a r a t u s u t i l i z e d a positive p r e s s u r e of a r g o n in the f u r n a c e c h a m b e r in addition to e v a c u a t i o n of the m o l d . F a l k e n h ag en and Hofmann e m p l o y e d a wedge s h a p e d m o l d , v a r y i n g f r o m 1 to 8 m m in t h i c k n e s s along i t s length. A c y l i n d r i c a l c o p p e r m o l d with an i n t e r n a l d i a m e t e r of 0.5 m m was u s e d in our work; h o w e v e r , the d i a m e t e r can e a s i l y be d e c r e a s e d to 0.25 m m or l e s s . The r e s u l t i n g q u e n c h e d s p e c i m e n i s a s h o r t w i r e of s m a l l d i a m e t e r which is e a s i l y a d a p t e d f o r u s e a s a t e n s i l e s p e c i m e n , o r fo r X - r a y d i f f r a c t i o n s t u d i e s . A b i n a r y A1-Mn a l l o y w a s c h o s e n f o r o u r p r e l i m i n a r y study s i n c e both the l a t t i c e p a r a m e t e r and the h a r d n e s s a r e known a s a function of the a m o u n t of m a n g a n e s e in solid s o lu ti o n , s'7 T h i s e n a b l e d us to i m m e d i a t e l y c o m p a r e o u r r e s u l t s with o t h e r s . 5 K o l e s nichenko has shown that at c o n c e n t r a t i o n s g r e a t e r than 4.5 wt pct Mn in a l u m i n u m , m e t a s t a b l e MnAI4 is f o r m e d . F o r this r e a s o n an A1-Mn a l l o y of an i n i t i a l m a n g a n e s e content of 2.40 wt pct was c h o s e n . In o r d e r to a s c e r t a i n the d e g r e e of o v e r s a t u r a t i o n , l a t t i c e p a r a m e t e r m e a s u r e m e n t s w e r e m a d e of the l i q u i d quenched m a t e r i a l s on a N o r e l c o d i f f r a c t o m e t e r usi n g the X - r a y powder t e c h n i q u e . A l a t t i c e p a r a m e t e r of 4.08/~ was d e t e r m i n e d which c o r r e s p o n d s to a s o l i d solution content of a p p r o x i m a t e l y 2.05 wt pct Mn, F i g . 2. Due to the s m a l l s i z e of the l i q u i d - q u e n c h e d s a m p l e s , a s p e c i a l g r i p p i n g t e c h n iq u e was u s e d f o r t e n s i l e t e s t i n g . A s m a l l bend w a s f o r m e d at e a c h end of the s a m p l e and a b a l l of H y s o l epoxy r e s i n was m o l d e d o v e r the bends. An a s q u e n c h e d s a m p l e and a s a m p l e p r e p a r e d with epoxy r e s i n a r e shown in F i g . 3. The g r i p s and the m a n n e r in which a s a m p l e i s h e l d for a t e n s i l e t e s t a r e shown in Fig. 4. The b o t t o m of the int e r n a l hole in the g r i p s , a g a i n s t which the epoxy b a l l on the s a m p
Data Loading...
