Mechanism of yield strength enhancement in heavily cold rolled phosphor bronze
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ment in heavily cold r o l l e d and thermally treated alloy 510. EXPERIMENTAL PROCEDURES AND RESULTS 1) Material and Processing Commercially hot r o l l e d alloy 510 was used as the starting m a t e r i a l for all the experiments w i t h the exception of the study evaluating the influence of alloy chemistry. For this latter study 11.5 lb (5.2 kg) ingots were induction melted u n d e r a charcoal cover. They were c h i l l cast into a s t e e l mold on a w a t e r cooled copper plate. The chemical analyses of all the alloys evaluated are listed in T a b l e I. Each alloy was cold rolled from m i l l e d hot r o l l e d plate with an end-for-end r e v e r s a l of direction between passes to provide m e t a l in various cold r o l l e d conditions at gages convenient for each specific experiment. The particular gages and reductions used are specified in the appropriate tables, figures, or text describing particular experiments. W h e r e required, an annealing treatment of 600°C for 1 h was used. 2) Tensile T e s t s Tensile testing was performed in an Instron tensile testing machine at a crosshead speed of 0.05 in.//min (1.27 m m / m i n ) . The tensile properties were d e t e r m i n e d with triplicate specimens, which were 1 in. (25.4 mm) gage (0.25 in. or 6.4 mm, wide) for the evaluation of the influence of chemistry and 2 in.
Table I. Alloy Compositions (Wt Pct) Used to Evaluate the Influence o f Chemistry on the Aging Response o f C A 510 Sn
P
3.72 5.12 6.43 4.64 5.37 4.91 6.02 4.4*
Fe
0.083 0.067 1.26
0.066 0.07
1.54 0.017
*CA510 also containing 0.1Zn, 0.03Ni, and 0.006Pb. VOLUME 8A, JANUARY 1977 111
( 5 0 . 8 m m ) gage l e n g t h (0.5 i n . o r 12.7 m m w i d e ) f o r t h e other studies. a ) C h e m i s t r y E f f e c t . E a c h a l l o y in T a b l e I s h o w e d a n i n c r e a s e i n t h e 0.01 p c t o f f s e t y i e l d s t r e n g t h of 7 t o 13 k s i (48 t o 90 M P a ) u p o n h e a t t r e a t m e n t . T h e m a g n i t u d e of t h i s i n c r e a s e w a s i n d e p e n d e n t of t h e t i n , phosphorous and iron contents over the r a n g e s exa m i n e d , n a m e l y , 3.72 t o 6 . 4 3 8 n , 0 t o 0 . 0 8 3 P , 0 t o 1 . 5 4 F e ( w t p c t ) . T h e s t r e n g t h of t h e a s - r o l l e d c o n d i tion i n c r e a s e s with tin and/7or iron c o n t e n t . b) R e s i d u a l S t r e s s E f f e c t . In o r d e r t o e v a l u a t e t h e c o n t r i b u t i o n o f r e l i e f of r e s i d u a l s t r e s s e s t o t h e h e a t t r e a t m e n t r e s p o n s e , a s t r i p o f m e t a l was cold r o i l e d f r o m hot r o l l e d p l a t e t o 0 . 0 3 0 i n . ( 0 . 7 6 m m ) . T h e s t r i p was t h e n r o i l e d to 0 . 0 2 0 i n . ( 0 . 5 3 r a m ) , o n e h a l f in f i v e e q u a l p a s s e s t h e o t h e r h a l f in t w e n t y e q u a t p a s s e s . A s s h o w n i n T a b l e I I , t h e y i e l d s t r e n g t h s of t h e m e t a l r o l l e d w i t h t w e n t y p a s s e s in t h e f i n a l s t e p a r e not s i g n i f i c a n t l y d i f f
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