The composition dependence of stacking fault energy in austenitic stainless steels
- PDF / 884,991 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 30 Downloads / 190 Views
T
H
E
s t a c k i n g fault e n e r g y of m e t a l s has long b e e n a p a r a m e t e r of i n t e r e s t b e c a u s e of its r o l e in such p h e n o m e n a as work h a r d e n i n g , 1 s t r e s s c o r r o s i o n c r a c k i n g , 2,3 and hydrogen e m b r i t t l e m e n t . 3 A u s t e n i t i c s t a i n l e s s s t e e l s have occupied a c e n t r a l place in this i n t e r e s t ; indeed, one of the e a r l i e s t m e a s u r e m e n t s of s t a c k i n g fault e n e r g y (SFE) was p e r f o r m e d on an F e - 1 8 C r - 8 Ni s t e e l . 4 Although the n u m e r o u s extant m e a s u r e m e n t s of s t a i n l e s s s t e e l SFE have b e e n r e v i e w e d s e v e r a l t i m e s , ~-v a r e c e n t r e a s s e s s m e n t of the l i t e r a t u r e data by S c h r a m m and Reed, 8 together with X - r a y faulting p r o b a b i l i t y m e a s u r e m e n t s on s o m e c o m m e r cial s t e e l s , 8 has r a i s e d s e v e r a l q u e s t i o n s . The f i r s t q u e s t i o n r e l a t e s to the c o n v e n t i o n a l technique of SFE d e t e r m i n a t i o n , u s i n g s t r o n g - b e a m , b r i g h t f i e l d i m a g e s of extended d i s l o c a t i o n nodes.9 It might be concluded, for e x a m p l e , that this technique could be used with confidence only to about 30 m J / m 2 (30 e r g / c m e ) , b a s e d on s e v e r a l s t u d i e s , 7,1~ and c e r t a i n l y with difficulty 8 above 50 m J / m 2. However, s i n c e Cockayne, Ray and Whelan ~1 r e p o r t e d that the p o s i t i o n of d i s l o c a t i o n l i n e s could be much m o r e a c c u r a t e l y determined using weak-beam, darkiield images, there have b e e n s e v e r a l r e p o r t s on SFE m e a s u r e m e n t s made by applying this method to s t a c k i n g fault r i b bons; ~2-~5 t h e s e SFE v a l u e s r a n g e up to 55 m J / m z with good confidence. ~2 The w e a k - b e a m method has also b e e n applied to extended nodes 14'~6 and e x c e l l e n t a g r e e m e n t with r i b b o n data as well as with s t r o n g - b e a m , b r i g h t - f i e l d data was obtained. To our knowledge, however, this technique has not been applied to s t a i n l e s s s t e e l s , and one p u r p o s e of the present work was to do so for a v e r y s t a b l e s t a i n l e s s s t e e l (AISI 310) of p r e s u m a b l y high SFE. A second q u e s t i o n r e l a t e s to the i n d i r e c t v a l u e s of S F E obtained by S c h r a m m and Reed 8 through t h e i r c o r r e l a t i o n 17 b e t w e e n X - r a y data on Ag, Au, Cu, A1, and Ni, and t h e i r e s t i m a t e of l i t e r a t u r e v a l u e s of SFE for t h e s e m e t a l s . F o r the m e t a l s Ag, Au, and Cu, t h e r e
CECIL G. RHODES is a Member of Technical Staff, Science Center, Rockwell International, Thousand Oaks, CA 91360. ANTHONY W. THOMPSON, formerly with the Science Center, Rockwell International, is now Associate Professor, Department of Metallurgy and Materials Science, Carnegie-MellonUniversity, Pittsburgh, PA
Data Loading...
