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DAMPING CAPACITY AND MECHANICAL
PROPERTIES OF Zn-Al ALLOY CASTINGS
T. Otani, K. Hoshino, T. Kurosawa
To cite this version:
JOURNAL DE PHYSIQUE
Colloque C5, suppldment au nOIO, Tome 42, oetobre 1981 page c5-935
DAMPING CAPACITY AND MECHANICAL PROPERTIES OF Zn-A1 ALLOY CASTINGS
T. O t a n i , K. H o s h i n o and T. K u r o s a w a
College of Industrial Technology, Nihon University, Narashino Chiba 275,
J a p a
Abstract.- This paper describes damping c a p a c i t y and mechanical p r o p e r t i e s o f Zn-8-20%A1 and Zn-8-20%Al-0.02-0.04XMg a l l o y c a s t i n g s . Zn-8-20%A1 a l l o y cast- i n g s show h i g h damping when quenched from 573K. Small amount o f Mg a d d i t i o n t o these a l l o y c a s t i n g s lowers damping c a p a c i t y considerably b u t e f f e c t i v e t o reduce decomposition through aging a t 423K f o r 48hrs a f t e r water quenched from 573K. According t o the r e s u l t s obtained i n t h i s i n v e s t i g a t i o n , t h e amount o f Mg added should be l e s s than 0.02%. A p p l i c a t i o n o f these a l l o y c a s t i n g s f o r a t t e n u a t i o n a r e discussed. 1 . I n t r o d u c t i o n . - R e c e n t l y i t h a s b e e n r e c o g n i z e d t h a t Zn-A1 a l l o y s show h i g h d a m p i n g when q u e n c h e d f r o m a b o v e e u t e c t o i d t e m p e r a t u r e ( 5 4 8 K ) . T h e m o s t o f s t u d i e s o n t h i s phenomenon w e r e d o n e w i t h r o l l e d o r d r a w n s p e c i m e n s . Zn-A1 a l l o y s a r e u s e d m o s t l y f o r c a s t i n g s , a n d g e n e r a l l y , s m a l l a m o u n t o f Mg a r e a d d e d t o t h e s e a l l o y c a s t i n g s i n o r - d e r t o i m p r o v e t h e i n t e r g r a n u l a r c o r r o s i o n r e s i s t i v i t y . The p u r p o s e o f t h i s i n v e s t i g a t i o n was t o m e a s u r e d a m p i n g c a p a c i t y a n d m e c h a n i c a l p r o p e r t i e s o f Zn-A1 a n d Zn-A1-Mg a l l o y c a s t i n g s . F r e q u e n c y a n a l y s i s f o r c a s t p l a t e s a n d c a s t t u b e j o i n t s w e r e d o n e t o e v a l u a t e t h e r e d u c - i n g e f f e c t o f v i b r a t i o n o f t h e s e a l l o y c a s t i n g s . 2. E x p e r i m e n t a l P r o c e d u r e . - C h e m i c a l c o m p o s i t i o n o f s p e c i m e n s a r e shown i n T a b l e 1 . A l l s p e c i m e n s w e r e h e a t t r e a t e d u n d e r t w o modes. 1 ) 573K x 2 h r .
-
W . Q . 2 ) 573K x 2 h r .-
W . Q . , 423K x 4 8 h r .-
W.Q. L o g a r i t h m i c d e c r e m e n t 6 a n d e l e c t r i c a l r e s i s t i v i t y w e r e m e a s u r e d f o r 2 x 5 ~ 1 0 0 mm s p e c i m e n s a t r o o m t e m p e r a t u r e . C h a r p y i m p a c t t e s t w e r e c a r - r i e d o u t f o r 1 0 x 1 0 ~ 5 0 rnm n o t c h l e s s s p e c i m e n s a t 273K. C a s t p l a t e s a n d c a s t t u b e j o i n t s w e r e m a n u f a c t u r e d f r o m Zn-8-20%A1 a l l o y s a n d q u e n c h e d f r o m 573K ( 573K x 4 h r .-
W . Q . ) . S i z e o f t h e p l a t e a n d t h e t u b e j o i n t w e r e shown i n F i g . 1 a n d F i g . 2 r e s p e c t i v e l y . F r e q u e n c y a n a l y s i s f o r c a s t p l a t e w e r e shown i n F i g . 3 . F r e q u e n c y o f t h e o s c i l l a t o r was c h a n g - e d f r o m 2 0 0 t o 3 0 0 0 H z . Same a n a l y s i s f o r c a s t s t e e l p l a t e a n d f l a k e g r a p h i t e c a s t i r o n p l a t e w e r e c a r r i e d o u t t o e v a l u a i t h e r e d u c i n g e f f e c t o f v i b r a t i o n o f Zn-A1 a l l o y c a s t i n g s . F i g . 4 i l l u s t r a t e sJOURNAL DE PHYSIQUE
Table 1 Chemical composition o f specimen. / %
[
F i g
.
F i g . 2 J o i n t f o r damping t e s t SpecimenCast i r o n box P i ck-up
-
7
vi::;tion SpectrumH
~i deo Speaker anal yser ~ l o t t e rI
Fig. 3 Schematic diagram o f experiment f o r p l a t e . 1 P l a t e f o r damping t e s t .
+-
l
PI c . JQ
Fig. 4 Schematic diagram of experiment f o r j o i n t .
JOURNAL DE PHYSIQUE 6 0 , 5 0 ae 40 4 30 c 2 0 $ 0 10
2
W 0 Mg I % Fig. 7 E f f e c t o f Mg on I h e t e n s i l e s t r e n g t h and elongation o f Zn-Al high damping alloy castings.Mg I %
Fig.8 E f f e c t o f Mg o n the Charpy !mpact, value end hardness of Zn-Al high damping alloy castings.
F i g . 1 0 s h o w s o n e o f t h e f r e q u e n c y a n a l y s i s f o r c a s t p l a t e r e c o r d e d by a s p e c t - rum a n a l y s e r . The f u n d a m e n - t a l r e s o n a n t f r e q u e n c y o f t h e c a s t i r o n box c a l c u l a t - e d f r o m f o l l o w i n g e q u a t i o n was 2422
Hz.
w h e r e f i s f u n d a m e n t a l r e s - o n a n t f r e q u e n c y o f t h e b o x , c i s v e l o c i t y o f s o u n d wave i n t h e a i r , L i s l e n g t h o f t h e b o x , W i s w i d t h o f t h e box a n d H i s h i g h t o f t h e b o x . I n F i g . 1 0 , 5 0 0Hz
p e a k ( f r o m t h e s p e a k e r ) a n d i t i s r e s o n a n t f r e q u e n c y p e a k s a n d 2400Hz
p e a k ( f u n d a m e n - t a l r e s o n a n t f r e q u e n c y o f t h e b o x ) a n d i t s r e s o n a n t f r e q u e n c y p e a k a r e o b s e r v e d . F i g . 11 s h o w s f r e q u e n c y a n a l-
y s i s f o r Zn-2O%Al a l l o y c a s t p l a t e q u e n c h e d f r o m 573K a n d c a s t s t e e l p l a t e when f r e q u e n c y o f s o u n d f r o m t h e s p e a k e r i s 7200Hz.
V i b - r a t i o n l e v e l o f Zn-2O%A1 a l - l o y c a s t p l a t e i s much l o w e r t h a n t h a t o f c a s t s t e e l p l a t e o v e r a l l f r e q u e n c y . F i g . 1 2 s h o w s f r e q u e n c y a n a l - y s i s f o r c a s t s t e e l p l a t e , Zn-15%A1-0.02%Mg a l l o y c a s t p l a t e , Zn-15%Al a l l o y c a s t p l a t e a n d Z n - 2 0 I A l a l l o y c a s t p l a t e when f r e q u e n c y o f s o u n d f r o m t h e s p e a k e r R T T E N U R T I O H : B d B F. S 1 8 d B / D I U 100 i 0 H Z F R E Q U E H C V 5 . 0 8 0 K H Z H R R K E R S 5 8 9 . 7 8 HZ-
3 9 . 6 d B U Fig.10 Frequency a n a l y s i s f o r c a s t p l a t e . - - - C a s t s t e e l ; -Zn-20%Al a l l o y 0 1 2 3 4 5 Frequency Vibrating a t 1200 Hz (: kHz1
Fig.11 Frequency a n a l y s i s f o r Zn-A1 a l l o y c a s t p l a t e .
1 2 3 4 5 Frequency [ kHz
1
Vibrating a t 800Hz
Fig.12 Frequency a n a l y s i s f o r Zn-A1 a l l o y c a s t p l a t e .
+ Cast s t e e l
-.,-.- Zn-15'~A1-0,02%Mg a1 l0y
JOURNAL DE PHYSIQUE 0-0 Cast i r o n 0-..- r-7 Cast s t e e l A. A---A Zn-lO%Al a l l o y
,m
100 0' 0----0 Zn-15%A1 a1 1 oy U 90 0 5 10 15 20 F r e q u e n c y [ kHz1
Fig.13 Frequency a n a l y s i s f o r c a s t j o i n t . ( 573Kx
4 h r . - W . Q . ).
i s 8 0 0 Hz. A l l Zn-A1 / Zn-A1-Mg a l l o y c a s t p l a t e s w e r e q u e n c h e d f r o m 573K. V i b r a t i o n l e v e l o f c a s t s t e e l p l a t e i s t h e h i g h e s t a n d t h a t o f Zn-20%Al a l l o y c a s t p l a t e i s t h e l o w e s t a n d Mg a d d i t i s o n l o w e r e d t h e r e - d u c i n g e f f e c t o f v i b r a t i o n o f Zn-A1 a l l o y c a s t i n g s . F i g . 1 3 s h o w s f r e q u e n c y a n a l y s i s f o r c a s t t u b e j o i n t s . F r e q u e n c y o f v i b - r a t i o n f r o m t h e o s c i l l a t o r was n o t s i n g l e a s t h e t e s t f o r p l a t e s , t h e - r e f o r e , v a r i o u s p e a k s a r e o b s e r v e d . V i b r a t i o n l e v e l o f Zn-A1 c a s t t u b e j o i n t s a r e l o w e r t h a n t h a t o f c a s t s t e e l , a n d Zn-15%Al a l l o y c a s t t u b e j o i n t q u e n c h e d f r o m 573K s h o w e d b e t t e r a t t e n u a t i o n t h a n c a s t i r o n e s - p e c i a l l y i n 13-20 kHz. 4 . C o n c l u s i o n . - Zn-A1 a l l o y c a s t i n g s q u e n c h e d f r o m 573K s h o w e d h i g h d a m p i n g b u t l o w e r v a l u e i n m e c h a n i c a l p r o p e r t i e s t h a n n o r m a l Zn-A1 a l - l o y c a s t i n g s . Amount o f Mg a d d e d t o t h e s e a l l o y c a s t i n g s s h o u l d be l e s s t h a n 0 . 0 2 % . Though t h e r e a r e many p r o b l e m s t o b e s o l v e d , Zn-A1 h i g h d a m p i n g a l l o y c a s t i n g s a r e e x p e c t e d t o b e a p p l i e d i n n e a r f u t u r e . R e f e r e n c e s( 1 ) K . N u t t a l 1 ; J . o f I n s t . o f M e t . 9 9 ( 1 9 7 1 ) , 266
( 2 ) K . I t o a n d K . F u j i m o t o ; J . o f t h e J a p a n I n s t . o f M e t . 4 3 ( 1 9 7 9 ) , 1 1 0 9
( 3 ) M.Sugiyama a n d C . T . L i n ; The J . o f t h e J a p a n F o u n d r y m e n ' s Soc:37 ( 1 9 6 5 ) , 1 1 0
( 4 ) I n t e r n a t i o n a l L e a d Z i n c R e s e a r c h O r g a n i z a t i o n , I n c . ; E n g i n e e r i n g P r o p e r t i e s o f Z i n k A l l o y s . 1 9 6 0 , 1 5 - 1 8