Effects of vanadium and nitrogen on recovery and recrystallization during and after hot-working some HSLA steels
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used in works p r a c t i c e . T h e y concluded that v a n a d i u m in t h e i r s t e e l s had little effect on the p r o c e s s e s which o c c u r d u r i n g hot r o l l i n g , but played a r o l e in the s t r u c t u r a l changes which e n s u e d u r i n g the s u b s e q u e n t h o l d ing p e r i o d at low t e m p e r a t u r e s (below 1323 K (1050~C)). T h e y concluded that in s p e c i m e n s r o l l e d at the lowest t e m p e r a t u r e s , p a r t i c l e s of VN a r e p r e c i p i t a t e d on the s u b b o u n d a r i e s of the a u s t e n i t e . U n f o r t u n a t e l y , t h e i r r e s u l t s , and those of s o m e other i n v e s t i g a t o r s , w e r e confused by the p r e s e n c e of e x c e s s a l u m i n u m in the s t e e l c a u s i n g p r e c i p i t a t i o n of A1N to o c c u r d u r i n g hot r o l l i n g and i s o t h e r m a l holding o v e r a wide t e m p e r a t u r e r a n g e . T h i s r a n g e i n c l u d e s the l o w - t e m p e r a t u r e s at which p r e c i p i t a t i o n of VN is thought to o c c u r . C o r d e a and Hook, 2 u s i n g a G l e e b l e t e c h n i q u e , c o m p a r e d the r e c r y s t a l l i z a t i o n d u r i n g hot w o r k i n g of a n i o b i u m (0.19 C, 0.011 Nb) and a v a n a d i u m (0.21 C, 0.59 V) s t e e l . They d e m o n s t r a t e d that for both s t e e l s worked at t e m p e r a t u r e s b e t w e e n 1088 K (815~ and 1198 K (925~ d y n a m i c a l r e c r y s t a l l i z a t i o n is r e t a r d e d by i n c r e a s i n g the p r i o r a u s t e n i t i z i n g ( s o l u t i o n izing) t e m p e r a t u r e f r o m 1373 K ( l l 0 0 ~ to 1573 K (1300~ The present study was designed to define the effects of vanadium and nitrogen more clearly, to separate dynamic from static effects, to quantify the kinetics of static recovery, recrystallizationand precipitation hardening, to determine the effects of changes in the vanadium concentration and V/N ratio and, most importantly, to eliminate extraneous effects due to the precipitation of AIN. Compositions were selected and M. J WHITEis with Norton Company, New Bond Road, Worcester, a deoxidation practice was adopted which ensured that MA 01601, and W. S. OWENis Head, Department of Materials Science the aluminum not tied up as oxide was negligible. As and Engineering,Massachusetts Institute of Technology, Cambridge, MA 02139. the e a r l i e r s t u d i e s %9 had shown that e f f e c t s due to Manuscript submitted November 10, 1978. v a n a d i u m a r e s i g n i f i c a n t only at low r o l l i n g t e m p e r a ISSN 0360-2133/80/0411-0597500.75/0 METALLURGICALTRANSACTIONSA 9 1980AMERICANSOCIETYFOR METALS AND VOLUME 11A, APRIL 1980-597 THE METALLURGICALSOCIETYOF AIME
Table 1. Compositions of Experimental Steels, Wt Pct
Steel No.
Code
C
Mn
Nb
V
A1 Total
A1 Soluble
N
V/N
1 2 3 4 5 6 7 8
Van 1 Van 2 Van 3 Van 4 Van 5 Van 6 Van 7 MIT 2A
0.11 0.11 0.10 0.10 0.11 0.12 0.11 0.11
1.35 1.36 1.45 1.38 1.35 1.39 1.41 1.35
-0.027 0.027 0.031
0.12 0.11
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