Quantitative magnetic analysis of plate-like martensite
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Table I. Chemical Analysis and Transformation Temperatures of Experimental Alloys
Identification
Fe
A B C D E F
60.35 58.63 55.23 57.33 63.97 62.37
Quantitative Magnetic Analysis of Plate-Like Martensite D.A.
COLLING
AND
Ni 30.44 29.01 26.42 30.17 31.15 30.61
Co
Mn
Si
8.50 11.65 17.60 11.81 4.21 6.65
0.50 0.50 0.53 0.50 0.50 0.35
0.11 0.11 0.10 0.I0 0.10 0.11
350
C
Ms, ~ A s" , C
0.017 - 83 0.017 - 36 0.011 - 10 0.017 < - 100 0.015 - 49 0.012 - 49
445 460 390 400 * *
*A s not determined
L. H. DUNN ,~
QUANTITATIVE a n a l y s i s of t h e v o l u m e f r a c t i o n of martensite or retained austenite following martensitic t r a n s f o r m a t i o n c a n b e a c c o m p l i s h e d by s e v e r a l e x p e r i mental techniques. Magnetic analysis, although inc l u d e d in t h e s e t e c h n i q u e s , i s g e n e r a l l y l i m i t e d to m a g n e t i c s a t u r a t i o n . Such quantitative a n a l y s i s has b e e n d e s c r i b e d in d e t a i l b y H o s e l i t z , ~ but m o r e r e c e n t l y , K r e n z e r a n d B a s k e s ~ h a v e d e t e r m i n e d the v o l u m e f r a c t i o n of m a r t e n s i t e f r o m a fit of a B r i l l o u i n f u n c t i o n to e x p e r i m e n t a l m a g n e t i c m o m e n t s m e a s u r e d b e t w e e n t h e C u r i e t e m p e r a t u r e of t h e a u s t e n i t e a n d t h e A s temperature. An a l t e r n a t i v e m a g n e t i c m e a s u r e m e n t , s t a t i c c o e r c i v e f o r c e , H c , h a s b e e n e m p l o y e d to f o l l o w t h e m a r tensite-to-austenite reverse transformation. ~ This s t u d y w a s c o n c e r n e d w i t h t h e c h a n g e in H c w i t h t e m p e r a t u r e a n d w i t h m i c r o s t r u c t u r a l c h a n g e s c a u s e d by t h e r e v e r s e t r a n s f o r m a t i o n , t h e r e f o r e w a s not d e p e n d e n t on t h e v o l u m e f r a c t i o n o f m a r t e n s i t e p e r s e . N e v e r t h e l e s s , the c h a n g e in H c a t r o o m t e m p e r a t u r e c a u s e d by the t r a n s f o r m a t i o n o f a u s t e n i t e to m a r t e n s i t e i t s e l f suggests a possible correlation between coercive force a n d the v o l u m e f r a c t i o n o f m a r t e n s i t e . G o o d e n o u g h ~ h a s c o n s i d e r e d the i n f l u e n c e of i n c l u s i o n s a n d p r e c i p i t a t e s o n t h e c r e a t i o n o f d o m a i n s of r e v e r s e m a g n e t i z a t i o n a n d , in t u r n , on H c of p o l y c r y s talline f e r r o m a g n e t i c m a t e r i a l s . His p r e d i c t i o n s indic a t e t h a t H c i s p r o p o r t i o n a l to t h e v o l u m e f r a c t i o n V o f the inclusion or precipitate. For granular inclusions, t h e p r o p o r t i o n a l i t y i s Ve/z, w h e r e a s f o r l a m e l l a r p r e c i p i t a t e s the p r o p o r t i o n a l i t y i s l i n e a r . A l t h o u g h G o o d e n o u g h d i d not s p e c i f i c a l l y t r e a t the c a s e of f e r r o m a g netic inclusions or precipitates, such considerat
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