A continuum description of anomalous yielding in anisotropic metals
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Fig. 2--Variation of mean overall size of sulfides, R, with homogenization time. Hot-rolled AISI 4340 low alloy steel specimens taken at various distances from the chill ha the original ingot9
p u b l i cat i o n 5 to which it r e f e r s c l e a r l y i n d i c a t e s that: 1) I n t e r f a c e diffusion of s u l f u r along the s u l f i d e / m a t r i x i n t e r f a c e c o n t r o l s the early s t a g e s of c o a r s e n i n g , d e s i g n a t e d as " o v u l a t i o n " , which c o n s i s t in the b r e a k i n g - u p of the el o n g at ed s u l f i d e s into s e g m e n t s that s u b s e q u e n t l y s p h e r o i d i z e . A j u s t i f i c a t i o n f o r this was p r e v i o u s l y offered; S 2) Subsequent c o a r s e n i n g of the new g e n e r a t i o n of fine, s p h e r i c a l p a r t i c l e s obviously by v o l u m e diffusion a c r o s s the m a t r i x and it is to this s t a g e that the G r e e n w o o d a n a l y s i s was applied. 6) We a r e well a w a r e that the s u l f i d e - m a t r i x i n t e r f a c e e n e r g y is v a r i a b l e with t i m e . P u b l i s h e d i n f o r m a tion on this p a r a m e t e r i s s o r a r e that we w e r e happy enough to find an a v e r a g e v a l u e for cr to plug into the c o a r s e n i n g k i n e t i c s e x p r e s s i o n . P e r h a p s the a u t h o r s of the d i s c u s s i o n could s u g g e s t a r e f e r e n c e f or a m o r e a c c u r a t e value of cr and, even b e t t e r , f o r i t ' s d e p e n d en ce on the m a t r i x and sulfide c o m p o s i t i o n s o r on time.
have no i n f o r m a t i o n on any s y n e r g i s i t i c e f f e c t of the 1. Y. V. Murty, T. Z. Kattamis,R. Mehrabian,and M.C. Flemings:Met. Trans.A, a l l o y i n g e l e m e n t s in the sulfide on the m i c r o h a r d n e s s 1977, vol. 8A, pp. 1275-82. of the i n c l u s i o n s , but it cannot be e x c l u d e d . 2. T. Z. Kattamis and M. C. Flernings: Trans. TMS-AIME, 1965,vol. 233, 3) The r e l a t i v e p l a s t i c i t y of the s u l f i d e s obviously pp. 992-99. depends on the m i c r o h a r d n e s s of both the sulfide and 3. E. DoroschKewitsch,R. Kiessling,and C. Westman:ZLS.L, 1970,vol. 208, p. 698. the m a t r i x . Sulfides away f r o m the c h i ll have b e e n 4. Y. V. Murty: Ph.D. Thesis,Dept. of Metallurgy,Universityof Connecticut. found to be c o a r s e r and s o f t e r than those c l o s e to the 5. Y. V. Murty,J. E. Mortal,T. Z. Kattamis, and R. Mehrabian:Met. Trans.A, chill, and to d e f o r m l e s s than the l a t t e r . T h e ex 1975,vol. 6A, pp. 2031-35. pl an at i o n can be b a s e d on the fact that in a l l p r o c e s s e d ingots the a s - c a s t m a t r i x n e a r the c h i ll is h a r d e r than away f r o m it. The extent to which cooling r a t e and A Continuum Description of Anomalous m a c r o s e g r e g a t i o n of a l l o y i n g e l e m e
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