The Density variation of a high-carbon steel wire with wiredrawing strain
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and coiled, then d e g r e a s e d and d e b r a s s e d by i m m e r s i o n in the solvent b a t h s . The d e n s i t y m e a s u r e m e n t s were made at 25.0~ by the " h y d r o s t a t i c w e i g h i n g " method with c o r r e c t i o n to v a c u u m ; the e q u i p m e n t has been des c r i b e d p r e v i o u s l y . * M e a s u r e m e n t s on a s t a i n l e s s s t e e l s t a n d a r d s p e c i m e n , r e p r o d u c i b l e to • g c m -s, were i n t e r m i x e d with the e x p e r i m e n t a l d e t e r m i n a t i o n s . * We could thus c o r r e c t for the m i n o r dif*Theabsolutedensityof the standardspecimen(-+0.01 pct) had beendeterminedpreviouslyby the "hydrostatic weighing"methodwithmonobromobenzeneof whichthe batch densityhad beendeterminedabsolutelywitha pycnometer. f e r e n c e s , due e i t h e r to batch i m p u r i t i e s or to c o n t a m ination d u r i n g u s e , b e t w e e n the a c t u a l d e n s i t i e s of the heavy liquids a n d s t a n d a r d values f r o m the l i t e r a t u r e . M o n o b r o m o b e n z e n e and d i b r o m o m e t h a n e were used at d i f f e r e n t t i m e s a s the liquid. In p r e p a r a t i o n s for the weighings in h e a v y liquid, a i r was expelled f r o m coils of the w i r e s with d i a m e t e r s a s s m a l l as 0.0068 in. m e r e l y by i m m e r s i o n with some shaking and k n e a d i n g . However, c o m p l e t e d i s p l a c e m e n t of the a i r f r o m the i n t e r s t i c e s of the f i n e - w i r e coils was difficult; a technique c o n s i d e r e d s a t i s f a c t o r y was developed only a f t e r s e v e r a l t e s t s . Each coil with wire d i a m e t e r 0.0045 in. or l e s s was placed in a v e s s e l e v a c u a t e d with a m e c h a n i c a l pump t h r o u g h a liquidn i t r o g e n t r a p ; while the pumping c o n t i n u e d , d e a e r a t e d d i b r o m o m e t h a n e was drawn into the c h a m b e r and onto the coil through a " b r e a k - s e a l " i m m e r s e d in a pool of the liquid f r e s h l y boiled. The v e s s e l with the i m p r e g n a t e d coil was then t r a n s f e r r e d to the t h e r m o s t a t e d bath for use a s the i m m e r s i o n v e s s e l in weighing. With the coil at a l l t i m e s c o m p l e t e l y i m m e r s e d , the p o s s i b i l i t y of a i r e n t e r i n g it in a t r a n s f e r o p e r a t i o n was e l i m i n a t e d . The d e n s i t i e s of the b r a s s - f r e e patented 0 . 0 2 8 - i n . diam wire and of the b r a s s - f r e e s p h e r o i d i z e d 0.028i n : d i a m wire w e r e the s a m e : 7.816 g c m -3. The density of b r a s s - c o a t e d patented 0 . 0 2 8 - i n . - d i a m wire was 7.813 g cm -3 n o t w i t h s t a n d i n g that 7 0 / 3 0 b r a s s is d e n s e r than s t e e l . C o m p a r a b l e r e s u l t s were found with wire d r a w n to 0.00450 in. d i a m , m e a s u r e d with the b r a s s left on and with the b r a s s r e m o v e d : 7.770 g c m -3 coated v s . 7.771 g c m -~ s t r i p p e d
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