The effect of quenching on recrystallization after hot working
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Table I. Alloy Composition, Wt Pct
Si
Mg
Fe
AI
0.37
0.39
0.21
remainder
All valuesin wt pct.
in a bath of m o l t e n s a l t and holding at this t e m p e r a t u r e f o r v a r i o u s p e r i o d s p r i o r to quenching. The t e m p e r a t u r e - d e f o r m a t i o n - t i m e h i s t o r y of the two s e r i e s is shown in F i g . 1. Th e t o t al d e l a y f r o m end of d e f o r m a t i o n to f i n i s h e d quenching in S e r i e s 1 was m e a s u r e d to about 1 s. Th e t i m e f o r the s p e c i m en to r e a c h the t e m p e r a t u r e of the s a l t bath was m e a s u r e d to about 1 s. Th e r e c r y s t a l l i z a t i o n p r o c e s s was followed m e t a l l o g r a p h i c a l l y by o p t i c a l m i c r o s c o p y of s a m p l e s quenched at i n t e r v a l s in the holding p e r i o d .
series 1
T
1. E"T. Turkdogan and S. lgnatowicz:Physical Chemistry of Process Metallurgy, Part 1, G. R. St. Pierre,ed., pp. 617-32, InstersciencePublishers, New York, 1961. 2. M. Hillert:Acta Met., 1955,vol.3, pp. 34-36. 3. V. G. Paranjpe, M. Cohen,M. B. Bever,and C. F. Floe: Trans. AIME, 1950, vol. 188, pp. 261-67. 4. T, Nishizawaand A. Chiba: Trans. JIM, 1975,vol. 16, pp. 767-78.
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The Effect of Quenching on Recrystallization After Hot Working H. G J E S T L A N D , O. LOHNE, AND N. RYUM It is g e n e r a l l y a c c e p t e d that d y n a m i c r e c r y s t a l l i z a t i o n does not o c c u r in A1 and A l - a l l o y s . l , 2 A f t e r hot w o r k i n g the m a t e r i a l m a y r e c r y s t a l l i z e if kept at the d e f o r m a t i o n t e m p e r a t u r e o r at t e m p e r a t u r e not f a r below this l e v e l . D u r i n g i n v e s t i g a t i o n of the r e c r y s t a l l i z a t i o n a f t e r hot w o r k in g of A 1 - M g - S i - a l l o y s 3 it was o b s e r v e d that the r a t e of r e c r y s t a l l i z a t i o n was g r e a t l y influenced by a w a t e r - q u e n c h a f t e r hot d e f o r m a t i o n . Some of those r e s u l t s a r e r e p o r t e d h e r e . In the p r e s e n t w o r k an a ll o y f r o m A//S R a u f o s s A m m u n i s j o n s f a b r i k k e r was e x a m i n e d . T h e c o m p o s i tion is given in T a b l e I. Two s e r i e s of e x p e r i m e n t s w e r e p e r f o r m e d :
T
Fig. 1--Temperature-deformation-time history in the two series.
TI
(~
49oi
S e r i e s 2 - W a t e r quenching a f t e r a d e f o r m a t i o n like in S e r i e s 1, r e h e a t i n g to the d e f o r m a t i o n t e m p e r a t u r e
47o
1892-VOLUME9A, DECEMBER 1978
Series 2
.........
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S e r i e s 1 - D e f o r m a t i o n in a t o r s i o n m a c h i n e to s = 3.64 at a m a x i m u m s t r a i n - r a t e of 1.82 s -1, holding at the d e f o r m a t i o n t e m p e r a t u r e f o r v a r i o u s p e r i o d s and w a t e r quenching (20~
H. GJESTLAND and O. LOHNE are with the Department of Metallurgy, The Foundation of Scientific and Industrial Research, Norwegian Institute of Technology, 7034 Trondheim-NTH, Norway. N. RYU
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