The influence of prior texture on the cold rolled texture of ti-al-4v
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(a)
Specimen Condition
Knoop Microhardness
As-Received 0.1 in. thick sheet As-Received 0.1 in. thick sheet/9 rain at 926~ (1700 ~F) (Nontransformed regions) As-Received 0.1 in. thick sheet/9 rain at 926~ (1700~ (transformed regions) As-Received 0.1 in. thick sheet/1 h at 1316~ (2400~ (material state B) Material state B/transversely rolled 48 pct Material state B/transversely rolled 48 pct/4 min at 732~ (1350~ (Nontransfonned regions) Material state B/transversely rolled 48 pet/9 mha at 732~ (1350~ (transformed regions)
409 332 309 290 614 586 371
NiCr a r e p o s s i b l e depending on the initial state and p r o c e s s i n g h i s t o r y p r i o r to annealing. The a s - r e c e i v e d TD-NiCr sheet (Material A) exhibited a p a r t i c u l a r l y l a r g e i n c r e a s e in grain s i z e upon annealing. C h a r a c t e r i s t i c s of this t r a n s f o r m a t i o n a r e such as to indicate that abnormal grain growth p r o c e s s e s were o c c u r r i n g following the f o r m a t i o n of the r e c r y s t a l l i z e d ultrafine grain s t r u c t u r e . However, it was also shown that m a t e r i a l s t a t e s produced f r o m cold r o l l i n g of the a s - r e ceived sheet had an annealing b e h a v i o r s i m i l a r to p r i m a r y r e c r y s t a l l i z a t i o n and n o r m a l g r a i n growth. The p r e s e n t investigation was supported by the National Aeronautics and Space A d m i n i s t r a t i o n under Grant NGL 36-003-094. 1. J. J. Petrovic and L. J. Ebert: Met. Trans., 1972, vol. 3, p. 1123. 2. J. J. Petrovic and L. J. Ebert: Met. Trans., 1972, voL 3, p. 1131. 3. J. J. Petrovic and L. J. Ebert: Met. Trans., 1973, vol. 4, p. 1301. 4. R. W. Cahn: in Physical Metatlurgy, R. W. Cahn, ed., p. 1148, North-HoUand, t 970.
(b) Fig. 4 - - M i c r o s t r u c t u r e of M a t e r i a l A f o l l o w i n g a n n e a l i n g at 927~ (1700~ (a) a f t e r 4 rain at t e m p e r a t u r e a n d (b) a f t e r 9 rain. M a g n i f i c a t i o n 150 t i m e s .
gions were s u b s t a n t i a l l y softer than the m a t e r i a l p r i o r to annealing and only slightly h a r d e r than the final l a r g e grain s t r u c t u r e as shown in Table I. It a p p e a r s evident that substantial r e c o v e r y a n d / o r r e c r y s t a l l i zation has o c c u r r e d with the f o r m a t i o n of the ultrafine g r a i n s p r i o r to the l a r g e g r a i n t r a n s f o r m a t i o n . S i m i l a r investigation of M a t e r i a l B, following 48 pct t r a n s v e r s e cold rolling, indicated that the t r a n s f o r m a tion was significantly different. At 927~ (1700~ the m a t e r i a l was c o m p l e t e l y t r a n s f o r m e d to a s m a l l grained r e c r y s t a l l i z e d s t r u c t u r e (grain size, 0.004 mm) in l e s s than 1 min. When annealing was p e r f o r m e d at 732~ (1350~ l i t t l e change in the cold worked s t r u c ture o c c u r r e d until a p p r o x i m a t e l y 9 min; at this point, the m a t e r i a l t r a n s f o r m e d r a p i d l y to a fine grain r
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