A comparison of the effects of explosive forming and static deformation on the mechanical properties of pressure vessel
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EXPLOSIVEf o r m i n g has
b e e n used s i n c e the 1950's as a method of m a k i n g s p e c i a l t y c o m p o n e n t s . The use of this f o r m i n g technique has b e e n l i m i t e d p r i m a r i l y to the a e r o s p a c e i n d u s t r y in the United States, w h e r e a s in E u r o p e and J a p a n it has gained b r o a d e r a c c e p t a n c e . To gain a c c e p t a n c e as a p r o d u c t i o n t e c h n i q u e , m a t e r i a l s p e c i f i c a t i o n s and r e q u i r e m e n t s of f o r m e d c o m p o n e n t s m u s t be equal or b e t t e r than those for a c o n v e n t i o n a l f o r m i n g p r o c e s s . The t e r m i n a l p r o p e r t i e s of explos i v e l y f o r m e d p a r t s have b e e n shown to be a function of the p a r t i c u l a r m a t e r i a l b e i n g f o r m e d ) Most of the data developed to date have b e e n on m a t e r i a l s Of i n t e r e s t p r i m a r i l y to the a e r o s p a c e i n d u s t r y , such as a l u m i n u m , t i t a n i u m , s t a i n l e s s s t e e l s , and s u p e r a l l o y s . T h e r e is r e l a t i v e l y little i n f o r m a t i o n r e l a t i n g the t e r m i n a l p r o p e r t i e s of e x p l o s i v e l y and c o n v e n t i o n a l l y f o r m e d s t e e l s . Most of the a v a i l a b l e data c o m p a r i n g d y n a m i c and static s t r a i n r a t e effects on s t e e l have b e e n i n t e s t s conducted u n i a x i a l l y . In these i n v e s t i gations 2-s the t e r m i n a l s t r e n g t h of the s t a t i c a l l y s t r a i n e d s t e e l s was g e n e r a l l y g r e a t e r than that obtained d y n a m i c a l l y . H a r r i s and White 6 d y n a m i c a l l y s t r a i n e d a 0.05 pct C s t e e l m a t e r i a l which had a higher h a r d n e s s than one s t a t i c a l l y s s t r a i n e d an e q u i v a l e n t amount. In two other c a s e s , 7" the h a r d n e s s of an e x p l o s i v e l y f o r m e d low c a r b o n s t e e l was l e s s than that of the h y d r a u l i c a l l y f o r m e d c o u n t e r p a r t . T h e s e r e s u l t s 7-8 a r e i n c o n s i s t e n t with the m a j o r i t y of o b s e r v a t i o n s on d y n a m i c a l l y s t r a i n e d s t e e l . Studies 9 on high s t r e n g t h low alloy s t e e l s indicated that t h e r e was s t r o n g o r i e n t a t i o n dependence upon the t e n s i l e and i m p a c t p r o p e r ties of explosively f o r m e d s t e e l s . I n a n o t h e r study 1~ of ship plate s t e e l t h e r e was a d e c r e a s e in the i m p a c t r e s i s t a n c e of e x p l o s i v e l y f o r m e d end c l o s u r e s that was not r e c o v e r e d by s t r e s s r e l i e f a n n e a l i n g . The p u r p o s e of the p r e s e n t study was to provide m o r e data on the t e r m i n a l p r o p e r t i e s of e x p l o s i v e l y f o r m e d s t e e l s . Two l o w - c a r b o n s t e e l s , A285 G r a d e C and HENRY E. OTTO and RICHARD W. SULLIVANare Senior Research Metallurgist and Research Chemist, respectively
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