The influence of austenite stability on the hydrogen embrittlement and stress- corrosion cracking of stainless steel
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it i s w e l l e s t a b l i s h e d that 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 c a n u n d e r g o b o t h i n t e r n a l 1-9 a n d g a s e o u s h y d r o g e n e m b i t t l e m e n t , 1°-~5 t h e r e h a s b e e n l i t t l e p r o g r e s s t o w a r d an understanding of the-mechanism, or mechanisms, of t h e s e f a i l u r e s . An immediate question c o n c e r n s t h e r o l e of a u s t e n i t e t r a n s f o r m a t i o n t o ~ ' a n d • m a r t e n s i t e s - c a n s i n g l e - p h a s e a u s t e n i t e be e m b r i t t l e d o r is m a r t e n s i t e f o r m a t i o n a p r e r e q u i s i t e ? T h i s i s s u e h a s b e c o m e c o n t r o v e r s i a l , 6,7,~°,n'~6-~ due i n p a r t t o c o m p a r i s o n o f d a t a f r o m a l l o y s w h i c h w e r e not w e l l c h a r a c t e r i z e d w i t h r e s p e c t to a u s t e n i t e s t a b i l i t y . F o r e x a m p l e , i t c a n n o t be a s s u m e d that a n o m i n a l l y s t a b l e g r a d e o f s t a i n l e s s s t e e l w i l l i n f a c t be s t a b l e , o r conv e r s e l y , t h a t a n o m i n a l l y u n s t a b l e g r a d e will undergo s t r a i n i n d u c e d t r a n s f o r m a t i o n ; o r t h a t a s t e e l w h i c h is s t a b l e u n d e r one type o f d e f o r m a t i o n o r e n v i r o n m e n t w i l l be s t a b l e u n d e r d i f f e r e n t c o n d i t i o n s . F u r t h e r , t h e possible effect o f a b s o r b e d hydrogen o n austenite s t a b i l i t y c a n n o t be o v e r l o o k e d . T h e p r e s e n t w o r k w a s c a r r i e d o u t t o i n v e s t i g a t e t h e r o l e of a ' m a r t e n s i t e i n the e m b r i t t l e m e n t p r o c e s s , a n d t h e s e u n c e r t a i n t i e s w e r e a v o i d e d by e x p e r i m e n t a l l y d e t e r m i n i n g t h e p r e s ence or a b s e n c e of a ' b e f o r e and a f t e r testing. T h e o c c u r r e n c e o f h y d r o g e n e m b r i t t l e m e n t (HE) i n t h e s e s t e e l s h a s b e e n m a n i f e s t e d by a r e d u c t i o n of d u c t i l i t y i n d y n a m i c t e n s i l e t e s t s , a n d by t h e a p p e a r a n c e of n o n d u c t i l e f r a c t u r e s u r f a c e s . F r o m a p r a c t i c a l p o i n t of v i e w , i t i s m o r e r e l e v a n t t o e s t a b l i s h whether delayed f a i l u r e o c c u r s u n d e r static s t r e s s e s . D. ELIEZER, formerly Research Associate, Department of Metallurgy and MiningEngineering, University of Illinois is now faculty member, Materials Engineering Department, Ben Gurion University of Negev, Beersheva, Israel. D. G. CHAKRAPANI, formerly Corrosion-ControlAnalyst with the Physical Plant at the University of Illinois, is now Director, MEI-Charlton Inc., Portland, OR 97201. C. J. ALTSTETTER and E. N. PUGH are professors, Department o f Metallurgy and Mining Engineering, University of Illinois, Urbana, IL 61801. Manuscript submitted February 2 3 , 1978. METALLURGICAL TRANSACTIONS A
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