Ultrasonic attenuation and velocity in SAE 52100 steel quenched from various temperatures
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Ultrasonic Attenuation and Velocity in SAE 52100 Steel Quenched from Various Temperatures EMMANUEL
Fig. 2--Transmission electron micrograph showing the dislocation distribution within subgrain. Thin foil specimens were made parallel to the p r i m a r y slip plane (T = 745~ T = 180 g per sq mm, and e = 10.6 pet in the region of steadystate creep).
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SCREW
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ANGLE BETWEEN THE BURGERS VECTOR AND DISLOCATION LINE Fig. 3--Histogram of the c h a r a c t e r of dislocations within subgrains in the region of steady-state creep. I. A. K. Mukherjee,J. E. Bird, and J. E. Dorn: ASM Trans. Quart., 1969, vol. 62, p. 155. 2. A. H. Clauer, B. W. Wilcox,and J. P. Hirth: Report BMI-X-517,BattelleMemorial Institute, Columbus, Ohio, 1968. METALLURGICAL TRANSACTIONS
P. PAPADAKIS
S E V E R A L i n v e s t i g a t o r s h a v e s t u d i e d the a t t e n u a t i o n of u l t r a s o n i c w a v e s in s t e e l , 1-7 and h a v e d r a w n the f o l l o w i n g c o n c l u s i o n s : 1) T h e a t t e n u a t i o n i s c a u s e d p r i n c i p a l l y by g r a i n s c a t t e r i n g , 2) T h e r e l e v a n t g r a i n s i z e i s the a u s t e n i t i c g r a i n s i z e b e f o r e c o o l i n g , 3) T h e s c a t t e r i n g p o w e r of the g r a i n s d e p e n d s upon the s i z e and e l a s t i c m o d u l i of the s u b s t r u c t u r e of the g r a i n s , b e i n g g r e a t e s t f o r l a m e l l a r p e a r l i t e and l e a s t f o r t e m p e r e d m a r t e n s i t e , and 4) T h e s c a t t e r i n g p o w e r can d e p e n d upon c a r b o n c o n t e n t , b e i n g m i n i m u m at the e u t e c t i c (0.8 pct C). It h a s a l s o b e e n s u g g e s t e d that s u b g r a n u l a r d i v i s i o n s (such a s m a r t e n s i t e p l a t e l e t s in h a r d e n e d s t e e l ) c o u l d b e i n d i v i d u a l s c a t t e r i n g centers. T o d a t e , m o s t of the e x p e r i m e n t a l w o r k h a s b e e n done with l o n g i t u d i n a l w a v e s . V e r y l i t t l e v e l o c i t y d a t a i s a v a i l a b l e . In the p r e s e n t e x p e r i m e n t a c o m p r e h e n s i v e s e t of d a t a h a s b e e n a m a s s e d on the a t t e n u a tion and v e l o c i t y of both l o n g i t u d i n a l and t r a n s v e r s e w a v e s in h a r d e n e d and t e m p e r e d s p e c i m e n s of a w e l l known type of s t e e l 8 a s f u n c t i o n s of a u s t e n i t i z i n g t e m p e r a t u r e and u l t r a s o n i c f r e q u e n c y . R e s u l t s a r e i n t e r p r e t e d in t e r m s of m e t a l l o g r a p h i c d a t a and g r a i n scattering theory. F i v e b l o c k s of SAE 52100 s t e e l w e r e c u t f r o m b a r s t o c k , and w e r e a u s t e n i t i z e d at 790 ~ 845 ~ 900 ~ 955 ~ and 1010~ f o r 1 h r , q u e n c h e d in oil at 40~ and i m m e d i a t e l y t e m p e r e d at 205~ f o r 1 h r to p r e v e n t c r a c k i n g . T w o p a r a l l e l f a c e s of e a c h w e r e t h e n g i v e n a v
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