Tensile properties of thermal-mechanically pretreated type 316 austenitic stainless steel
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Hardness Anisotropy of Magnetically Anisotropic Alnico-V Single Crystal KAZUMI SHIMOTORI, MASAMI MIYAUCHI, AND YOSHIHARU FUKA SAWA Fig. 3 - - M i c r o s t r u c t u r e of t r e a t m e n t C1 a f t e r aging 1000 h at 650~ Note l a r g e quantity of s i g m a p h a s e . Magnification 420 times.
at 77 K; thus s u b z e r o deformation has much l e s s effect on the p r o p e r t i e s of type 316 s t e e l than it would have on l e s s stable types. The data for s a m p l e s whose grain s i z e was refined by s u c c e s s i v e cold working and annealing t r e a t m e n t s (C1 t r e a t m e n t of p a r t I) is of i n t e r e s t b e c a u s e of the finer grain size and also b e c a u s e it develops l a r g e quantities of s i g m a phase in the m i c r o s t r u c t u r e a f t e r aging, see Fig. 3 and p a r t I. Although the yield and u l t i m a t e t e n s i l e strength of this m a t e r i a l in an unaged condition is much higher than for a s - s o l u t i o n t r e a t e d type 316 due to g r a i n refinement, the yield strength is s t i l l c o n s i d e r a b l y lower than for m a t e r i a l of s i m i l a r grain s i z e p r e p a r e d by the pulse heating technique, see Ref. 7. This difference is p r e s u m a b l y caused by the fact that the C1 t r e a t m e n t c a u s e s p r e c i p i t a t i o n of solid solution strengthening e l e m e n t s , p r i m a r i l y in the f o r m of l~sC 8 c a r b i d e s . Aging of this m a t e r i a l leads to an i n c r e a s e in yield and ultimate t e n s i l e strength, c o n t r a r y to the trend o b s e r v e d on aging the other p r e t r e a t m e n t s studied. This is evidently c a u s e d by the l a r g e amount of s i g m a f o r m e d in this m a t e r i a l on aging. Although the formation of s i g m a does cause some reduction, the ductility is s t i l l quite substantial at both room t e m p e r a t u r e and 650~ The s o - c a l l e d Garofalo t r e a t m e n t (E) which is used to obtain improved c r e e p p r o p e r t i e s ~ has about the s a m e effect on short t i m e t e n s i l e p r o p e r t i e s a f t e r 1000 h aging at 650~ as a s t r a i g h t 15 pct reduction would have. Thus, the low t e m p e r a t u r e t r e a t m e n t to nucleate c a r b i d e s on the d i s l o c a t i o n s does not a p p e a r to provide any unique benefits for the short time tens i l e p r o p e r t i e s a f t e r aging. The authors acknowledge the support of this work by the U.S.A.E.C. through c o n t r a c t AT-(40-1)-4044. 1. J. E. Spmiell, J. A. Scott, C. S. Ary, and R. L. Hardin: Met. Trans., 1973, vol. 4, p. 1533. 2. G. P. Sanderson and D. T. Llewellyn: J. Iron Steellnst., 1969, vol. 207, p. 1129. 3. D. Fahr, E. E. Bloom, and J. O. Stiegler: Proceedings of Conference on Irradiation Embrittlement and Creep in Fuel Cladding and Core Components, British Nuclear Energy Society, London, November, 1972, p. 167. 4. J. T. Barnby: J. Iron Steellnst., 1965, vol. 203, p. 392. METALLURGICAL TRANSACTIONS
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