Fracture of alloy steels by intergranular microvoid coalescence as influenced by composition and heat treatment
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in Fig. 3 of our p a p e r . If In20 were a l t e r i n g the c a l i b r a t i o n over an 80 d e g r e e r a n g e of t e m p e r a t u r e , why would it not a l t e r the l i n e a r r e l a t i o n s h i p b e t w e e n in ain and 1/T over the s a m e span ? In s u m m a r y , it is our opinion that the e x i s t e n c e of In20 m o l e c u l e s in the vapor is of no c o n s e q u e n c e . If Jacob and Alcock a r e a w a r e of any m o l e c u l e or any atomic s p e c i e s that might be p r e s e n t that a b s o r b s s t r o n g l y at 3039.36A (or within the s p e c t r a l slit width of this wavelength) and not at 2836.92/~, they should focus t h e i r a r g u m e n t s a g a i n s t the technique on that s p e c i e s . These a r g u m e n t s should depend on known a b s o r p t i o n s p e c t r a , not t h e r m o d y n a m i c s t a b i l i t y of p o s sible s p e c i e s . I n t r o d u c t i o n of a c a l c u l a t i o n of s i g n i f i cant p r e s s u r e s of In20, or of f a i l u r e to deoxidize the s p e c i m e n s , is o t h e r w i s e a specious a r g u m e n t . i. J. Ramirez-Munoz Atomic Absorpnon Spectroscopy, Elsevmr Press, New York, 1968. 2. A. N. Nesmeyanov VaporPressure of the Elements, p. 452, Academic Press, New York, 1963 3. Analytical Methods for Atonnc Absorption Spectrophotometry, Perkln-Elmer Corp., Norwalk, Connecticut, 1966. 4. R. W B Pearse and A. G. Gaydon Theldentlfication of Molecular Spectra. 3rd ed., p. 191, Chapman and Hall, London, 1965.
Fracture of Alloy Steels by Intergranular Microvoid Coalescence as Influenced by Composition and Heat Treatment B. J. SCHULZ AND C. J. McMAHON, JR.
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the c o u r s e of a study of t e m p e r e m b r i t t l e m e n t in a s e r i e s of 3.5 pct N i - l . 7 pct C r - b a s e d s t e e l s , n u m e r o u s o b s e r v a t i o n s w e r e made of a f r a c t u r e mode i n v o l v i n g i n t e r g r a n u l a r m i c r o v o i d c o a l e s c e n c e (IMC) on the high t e m p e r a t u r e side of the d u c t i l e - b r i t t l e t r a n s i t i o n . I Although the r e a s o n for this was not u n d e r s t o o d at the t i m e , l a t e r work showed that this effect (which r e d u c e s f r a c t u r e toughness) is r e l a t e d to the r a t h e r old m e t a l l u r g i c a l p r o b l e m of " o v e r h e a t i n g " of alloy s t e e l s The u n d e r s t a n d i n g of this phenornenon can be i m p o r t a n t in t h e r m a l p r o c e s s i n g of low Mn s t e e l s where high a u s t e n i t i z i n g t e m p e r a t u r e s a r e used, as in forging o p e r ations. IMC was found to be caused by the s p e c i a l a u s t e n i t i z a t i o n t r e a t m e n t used: 1250~ for 4 h, followed by a f u r n a c e cool to 900~ a 24 h hold, and an oil quench to r o o m t e m p e r a t u r e . This was followed by a t e m p e r i n g t r e a t m e n t of 2 h at 650~ and s o m e t i m e s by an aging t r e a t m e n t at a lower t e m p e r a t u r e . A d i r e c t oil quench f r o m 1250~ e l i m i n a t e d the IMC.
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