Elevated temperature deformation of TD-nickel
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e t e r , L / D ~ 1). This a s - e x t r u d e d m a t e r i a l r e c e i v e d a s t a n d a r d i z a t i o n anneal for 1 h at 1589 K (2400~ in a r gon to match the annealing conditions of other g r a i n s i z e s . The anneal had no apparent effect on a s - e x t r u d e d grain size or shape. A l a r g e grain s i z e (~ 0.4 mm a v e r a g e g r a i n d i a m e t e r , L / D ~ 3) was produced from the a s - e x t r u d e d state by cold r o l l i n g t r a n s v e r s e to the extrusion axis ( t r a n s v e r s e rolling) and annealing. The r o l l i n g reduction was 33 pct in thickness. Rolled s a m p l e s were annealed for 1 h at 1589K (2400~ in argon. This p r o c e d u r e p r o duced m a t e r i a l whose volume was 100 pct l a r g e grained. Development of these l a r g e g r a i n s was the r e s u l t of a b n o r m a l grain growth. 8,9 Previous work 8'9 had suggested that an i n t e r m e d i a t e g r a i n size could be produced by deformation and annealing, i f the starting material was large grained. This proved to be the case. 100 pct large g r a i n e d m a t e r i a l was cold r o l l e d to a 70 pct reduction in t h i c k n e s s ( r o l l ing d i r e c t i o n t r a n s v e r s e to the original a s - e x t r u d e d axis). Following rolling, s a m p l e s were annealed for 1 h at 1366 K (2000~ in vacuum to produce an i n t e r mediate grain s i z e (~ 0.02 mm a v e r a g e g r a i n d i a m e t e r , L I D ~ 1), and then for 1 h at 1589 K (2400~ in argon as a s t a n d a r d i z a t i o n anneal. The i n t e r m e d i a t e grain size was e s t a b l i s h e d by the 1366 K (2000~ anneal. This anneal was employed in o r d e r to heat r o l l e d s a m p l e s r a p i d l y to t e m p e r a t u r e (by room t e m p e r a t u r e i n s e r t i o n into the hot zone). Slower heat-up r a t e s p r o m o t e d the formation of a r e covered s t r u c t u r e , r a t h e r than a distinct i n t e r m e d i a t e grain s t r u c t u r e (no effect of heat-up r a t e was noted in the production of the l a r g e grain size). The final 1589 K (2400~ anneal had no influence on the i n t e r m e d i a t e grain s i z e produced by the 1366 K (2000~ anneal.
Table I. Vendor's Chemical Analysis of TD-Nickel As-Extruded 7.62cm (3 in.) Bar
Grain Size Control
Element
Wt Pet
The grain size of the a s - e x t r u d e d b a r was employed as a s m a l l grain size (N 0.001 mm a v e r a g e grain d i a m -
C S Cu Ti Co Fe Cr ThO: Ni
0.0063 0.0010 0.002 0.001 0.060 0.007 0.001 2.6 Bal
J. J. PETROVIC is Research Scientist, Aerospace Research Laboratories, Metallurgy and Ceramics Research Laboratory, Wright-Patterson Air Force Base, Dayton, Ohio 45433. L. J. EBERT is Professor o f Metallurgy and Materials Science, Case Western Reserve University, Cleveland, Ohio 44106. Manuscript submitted August 14, 1972. METALLURGICAL TRANSACTIONS
VOLUME 4, MAY 1 9 7 3 - 1 3 0 1
G r a i n Shape C o n t r o l G r a i n s h a p e c o n t r o l was a c h i e v e d by swaging and a n n e a l i n g o p e r a t i o n s .
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