A HIGH TEMPERATURE INTERNAL FRICTION STUDY OF THE RARE EARTH ELEMENT IN 16MN STEEL

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A HIGH TEMPERATURE INTERNAL FRICTION STUDY OF THE RARE EARTH ELEMENT IN 16MN

STEEL

Yu-He. Sheng, W. Li, G. Yang

To cite this version:

Yu-He. Sheng, W. Li, G. Yang. A HIGH TEMPERATURE INTERNAL FRICTION STUDY OF

THE RARE EARTH ELEMENT IN 16MN STEEL. Journal de Physique Colloques, 1985, 46 (C10),

pp.C10-399-C10-402. �10.1051/jphyscol:19851090�. �jpa-00225475�

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JOURNAL DE PHYSIQUE

Colloque C10, suppl6ment au n012, Tome 46, dbcembre 1985 page C10-399

A HIGH TEMPERATURE INTERNAL FRICTION STUDY OF THE RARE EARTH ELEMENT IN 16MN STEEL

YU-HE. SHENG, W.B. L I and G . P . YANG

P h y s i c s D e p a r t m e n t o f B e i j i n g U n i v e r s i t y o f I r o n and S t e e l T e c h n o l o g y , B e i j i n g , C h i n a

A b s t r a c t

-

F i v e k i n d s o f s p e c i m e n s o f 16Mn s t e e l were c o n t a i n e d a s m a l l amount o f Cerium o f d i f f e r e n t c o n t e n t s (1,O; 2,0.028wt%;

3,0.050wt%; 4 , 0 . 1 2 w t % , 5 , 0 . 0 8 3 w t % ) . An i n t e r n a l f r i c t i o n p e a k n e a r 600 OC ( f ~ 0 . 6 5 ~ z j was o b s e r v e d w i t h t o r s i o n pendulum. The a c t i v a t i o n e n e r g y o f t h i s peak was found t o b e a b o u t 2.5eV, which

t h e specimen c o n t a i n e d Ce e l e m e n t a f t e r Carbon a n d N i t r o g e n were removed. But no peak was a b s e r v e d which t h e specimen d i d n o t c o n t a i n a n y r a r e e a r t h e l e m e n t . I t was a b s e r v e d t h a t t h e peak o f s p e c i m e n , c o n t a i n i n g some r a r e e a r t h e l e m e n t , e i t h e r a p p e a r e d o r d i s a p p e a r e d w i t h t h e d i f f e r e n t h e a t - t r e a t m e n t p r o c e d u r e . The m i c r o a n a l y s i s w i t h EPNA showed t h a t 0.308wt% w a s t h e c o n t e n t o f Cerium e l e m e n t i n t h e g r a i n boundary a r e a where no i n c l u s i o n e x i s t a n c e , on which t h e X-ray w a s i r r a d i a t e d .

Based on t h e c h a r a c t e r s o f i n t e r n a l f r i c t i o n p e a k s i n t h i s work a n d t h e f o r m e r r e s e a r c h e s o f t h e r a r e e a r t h i n t e r n a l f r i c t i o n , i t may be con.cluded t h a t t h e p e a k s a r e t h e s o l i d s o l u t i o n peak o f Cerium e l e m e n t i n 1 6 ~ n s t e e l . The mechanism o f t h e s o l i d s o l u t i o n o f Cerium i n 1 6 ~ n s t e e l w i l l b e d i s c u s s e d .

I

-

INTRODUCTION

The s t a t u s o f t h e r a r e e a r t h e l e m e n t i n i r o n a n d s t e e l a l l o y s , a n d t h u s t h e mechanism o f t h e e f f e c t o f r a r e e a r t h e l e m e n t s on t h e p r o p e r - t i e s of i r o n a n d s t e e l , a r e p r o b l e m s o f g r e a t i n t e r e s t a n d d e s e r v e f u r t h e r i n v e s t i g a t i o n s . We can o b t a i n v a l u a b l e i n f o r m a t i o n s a b o u t t h e d i s t r i b u t i o n a n d movement o f t h e s m a l l amount o f i m p u r i t y a t o m s i n m e t a l by i n t e r n a l f r i c t i o n method which i s h i g h l y s e n s i t i v e t o t h e c h a n g e o f t h e m i c r o - s t r u c t u r e o f t h e m e t a l c o n c e r n e d . I n t h i s work, t h e e f f e c t o f a small amount o f r a r e e a r t h e l e m e n t Ce i n 16Mn s t e e l on t h e g r a i n boundary i n t e r n a l f r i c t i o n was s t u d i e d . The e x i s t e n c e o f Ce i n t h e g r a i n boundary a r e a where no i n c l u s i o n e x i s t e d w a s a l s o conformed

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19851090

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C10-400 JOURNAL DE PHYSIQUE

by t h e m i c r o - a n a l y s i s o f t h e EPPiA ( E l e c t r o n P r o b e N i c r o - A n a l y s i s ) a t t h e same t i m e . The e x p e r i m e n t a l r e s u l t s showed t h a t Ce e l e m e n t r e a l l y d i s s o l v e s i n 16Mn s t e e l .

I1

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EXPERIMENTAL METHOD

The s p e c i m e n s u s e d i n t h i s work were p r e p a r e d from 16 Mn s t e e l c o n t a i n - i n g a s m a l l amount o f Ce e l e m e n t o f d i f f e r e n t c o n t e n t s : 1,O; 2,0.028 wt%; 3,0.050wt%; 4,0.120wt%; 5,0.083wt%. O t h e r i m p u r i t i e s i n t h e s p e - cimens were t h e same, t h e y a r e : C,0.14wt%; S i , O . 3 l w t % ; Mn,1.22wt%; P, 0.030wt%; ~ 1 , 0 . 0 7 w t % ; S,3O-40 ppm.

B e f o r e t h e measurements o f i n t e r n a l f r i c t i o n , a l l t h g f i v e s p e c i m e n s were h e a t e d i n a n a t m o s p h e r e o f wet hydrogen a t 720 C f o r 2 4 h o u r s i n o r d e r t o remove Carbon a n d N i t r o g e n . The i n t e r n a l f r i c t i o n w a s measur- -ed w i t h a t o r s i o n pendulum / I / , t h e specimen m a i t a i n e d i n a n atmos- p h e r e o f Argon when h e a t e d a n d measured. The measurement o f e v e r y s p e c i m e n was r e p e a t e d u n d e r t h e same c o n d i t i o n e x c e p t a s m a l l change o f f r e q u e n c y . I n o r d e r t o o b s e r v e t h e v a r i a t i o n s o f i n t e r n a l f r i c t i o n c u r v e s , t h r e e s p e c i m e n s ( 1 , 2 , 4 ) w e r e t r e a t e d a c c o r d i n g t o t h e f o l l o w - i n g p r o c e d u r e : F i r s t , t h e s p e c i m e n s were h e a t e d a t 9 8 0 ' ~ f o r 8 h o u r s a n d t h e n quenched i n t o w a t e r ; a f t e r h e a t e d t o 910 O C , f o l l o w e d by a n n e a l i n g t o room t e ~ e r a t u r e i n t h e f u r n a c e ; f i n a l l y , t h e s p e c i m e n s were h e a t e d a t 1100

!

f o r 7 h o u r s a n d t h e n quenched i n t o w a t e r . A f t e r e v e r y t r e a t m e n t t h e measurement m e n t i o n e d a b o v e were r e p e a t e d a n d t h e g r a i n s i z e s o f specimen 2 a n d 4 were measured w i t h a m e t a l l o g r a p h i c m i c r o s c o p e . F i n a l l y , t h e m i c r o a n a l y s i s of g r a i n boundary a r e a o f s p e c - imen 4 w i t h EPMA o f EM-400 was made.

I11

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EXPERIMENTAL RESULTS

An i n t e r n a l f r i c t i o n peak n e a r 600 O C was o b s e r v e d f o r a l l t h e s p e c i - mens c o n t a i n i n g Ce e l e m e n t a f t e r Carbon a n d N i t r o g e n were removed, b u t no peak was o b s e r v e d f o r t h e specimen c o n t a i n i n g no r a e r e a r t h e l e m e n t . I n f i g u r e , A ( ' ) shows t h e c u r v e s o f s p e c i m e n s a f t e r Carbon a n d N i t r o g e n removed, B(x) shows t h e c u r v e s o f s p e c i m e n s a f t e r q u e n c h i n g a t 980 O C ,

shows

t h e c u r v e s o f s p e c i m e n s a f t e r a n n e a l i n g from 910 OC t o room t e m p e g a t u r e , D(+) shows t h e c u r v e s o f s p e c i m e n s a f t e r q u e n c h i n g a t 1100 C. Every e x p e r i m e n t a l c u r v e was r e p e a t e d f o r s e v e r a l t i m e s u n d e r t h e same c o n d i t i o n u ti1 t h e same i n t e r n a l f r i c t i o n c u r v e w a s o b t a i n e d a c c u r a t e l y n e a r 600 'C. The h i g h t e m p e r a t u r e a c h g r o u n d i n t e r n a l f r i c - t i o n c u r v e s was o b t a i n e d from t h e r e l a t i o n

P-'=

A exp(-U/kT) /2/ where t h e p a r a m e t e r s A a n d U were t a k e n from t h e e x p e r i m e n t a l d a t a s o t h e r t h a n t h e peak a r e a by m a t h e m a t i c a l r e g r e s s i o n method, t h e main p a r a - m e t e r s o f t h e s e p e a k s a r e a s f o l l o w s :

No. Optimum Tempb o f ( F r e q u e n c y o f Peak A c t i v a t i o n t h e P e a k s ( C ) V i b r a t i o n ( H z ) ) H e i g h t Energy(eV) 2 5 9 8 . 7 ( 0 . 7 2 4 ) 597.2 (0.677) 2 7 x 1 0 - ~ 2.9

3

611.8 (0.689) 6 1 4 . 2 ( 0 . 7 4 6 ) 3 5 x 1 0 1 ~ 2.2

4 605.6 ( 0 . 7 1 2 ) 601.7 (0.611) 35x10-: 2.6

5

594.9 ( 0 . 5 9 9 ) 600.2 ( 0 . 7 1 9 ) 35x10 2 . 3

I t was o b s e r v e d from t h e v a r i a t i o n s o f t h e i n t e r n a l f r i c t i o n c u r v e s o f d i f f e r e n t h e a t - t r e a t m e n t p r o c e d u r e t h a t t h e p e a k s o f s p e c i m e n s con- t a i n i n g Ce e l e m e n t d i s s a p e a r e d a f t e r q u e n c h i n g a t 980°C, & h e p e a k s a p p e a r e d s l i g h t l y a f t e r a n n e a l i n g a t t e m p e r a t u r e n e a r 900 C a n d dis- a p p e a r e d a g a i n a f t e r q u e n c h i n g a t 1 1 0 0 ~ ~ . T h i s phenomenon was n o t o b s e r v e d on t h e i n t e r n a l f r i c t i o n c u r v e s o f t h e specimen c o n t a i n i n g no Ce e l e m e n t . The a v e r a g e g r a i n s i z e was from 40 grain/mm t o 10 grain/mm

,

a n d no d i r e c t c o r r e s p o n d i n g r e l a t i o n s between t h e g r a i n s i z e a n d t h e r i s e a n d f a l l o f t h e i n t e r n a l f r i c t i o n p e a k s w a s o b s e r v e d . The micro- a n a l y s i s w i t h EPMA showed t h a t t h e c o n t e n t o f C e e l e m e n t i n t h e a r e a

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on which t h e X-ray was i r r a d i a t e d was 0.308 w t % . I V

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DISCUSSION

A s we know t h a t r a r e e a r t h e l e m e n t s e x i s t i n i r o n a n d s t e e l a l s o as i n c l u s i o n s , b u t t h e h e a t - t r e a t m e n t mentioned above d o e s n o t change t h e s t a t u s o f t h e atoms o f r a r e e a r t h e l e m e n t s i n them /3/. The experimen- t a l r e s u l t showed t h a t t h e i n t e r n a l f r i c t i o n p e a k s n e a r 6 0 0 ~ ~ s h o u l d b e c o r r e l a t e d t o t h e a t o m s , t h e s t a t u s o f which was a f f e c t e d by s o l i d t r a s f o r m a t i o n s o f t h e s t e e l . T h e m i c r o a n a l y s i s w i t h EPMA showed t h e t r a c e o f Ce e l e m e n t s e g r e g a t i n g a t t h e g r a i n boundary a r e a where no i n c l u s i o n s h o u l d e x i s t . I t may b e c o n s i d e r e d t h a t t h e Ce atoms d i s - s o l v e d i n s t e e l 16 Mn g i v e r i s e t o t h e i n t e r n a l f r i c t i o n p e a k s n e a r 6 0 0 ' ~ . I f t h e number of Ce atoms i s c o r r e s p o n d i n g t o t h e number o f r e l a x a t i o n u n i t s p r e s e n t i n t h e r e l a x a t i o n p r o c e s s e s / 4 / , . i t may b e r o u g h l y e s t i m a t e d from t h e n o n - i n c r e a s i n g of t h e peak h e i g h t w i t h t h e i n c r e a s i n g of t h e c o n t e n t of Ce e l e m e n t i n specimens t h a t t h e number o f Ce atoms d i s s o l v e d i n s t e e l 16 Mn a t room t e m p e r a t u r e i s no more t h a n 0.05 w t % .

Based on t h e c h a r a c t e r s o f i n t e r n a l f r i c t i o n peaks i n t h i s work and t h e former r e s e a r c h e s on t h e r a r e e a r t h i n t e r n a l f r i c t i o n / 5 , 6 / , i t may be c o n c l u d e d t h a t t h e peaks a r e t h e s o l i d s o l u t i o n peak ( i . e . SS peak) of Ce element i n s t e e l 16 Mn. I now t r y t o e x p l a i n t h e experimen- t a l phenomenon a s f o l l o w s :

The s e g r e g a t i o n o f Ce element a t t h e g r a i n boundary a r e a i n s t e e l h a s a l s o been o b s e r v e d i n e x p e r i m e n t s . The d i f f e r e n c e s o f e q u i l i b r i u m con- c e n t r a t i o n between t h e Ce atoms a t t h e g r a i n boundary a r e a a n d t h a t i n t h e i n t e r i o r o f g r a i n s d i m i n i s h e s when t h e t e m p e r a t u r e f a l l s . Because t h e r e i s n o t enough t i m e f o r Ce atmos t o a c h i e v e t h e e q u i l i b r i u m d i s - t r i b u t i o n a t room t e m p e r a t u r e by d i f f u s i o n i n q u e n c h i n g , t h e concen- t r a t i o n o f Ce atoms a t t h e g r a i n boundary a r e a a f t e r quenching i s l o w e r t h a n t h e e q u i l i b r i u m c o n c e n t r a t i o n a t room t e m p e r a t u r e , a n d t h e SS peak r e l a t e d t o t h e c o n c e n t r a t i o n of Ce atoms a t t h e g r a i n boundary a r e a f a l l s o r d i s a p p e a r s . T h e r e i s more t i m e f o r Ce atoms t o r e t u r n t o t h e g r a i n boundary a r e a i n a n n e a l i n g t h a n i n q u e n c h i n g , s o t h a t t h e SS peak a p p e a r s a g a i n a f t e r a n n e a l i n g .

tcr., Q4 0 . 0 )

r.06

8.05

0 09

403

0 01

0.01

.--. - ¹⁰⁰⁰

1.40 ,.)5 i.)o 1.21 I . l D 1.15 I I V ( . a 5 1.o ' ^I-

-

F i g . 1

-

Specimen 1

,

c o n t a i n i n g no r a r e e a r t h element. Curve A , by o r i g i n a l d a t a ; Curve B, a f t e r a n - n e a l i n g a t 980°C f o r 8 h o u r s a n d q u e n c h i n g i n t o w a t e r ; Curve C , a f t e r a n n e a l i n g from 910°C t o room t e m p e r a t u r e ; Curve D , a f t e r a n n e a l i n g a t 1 1 OOOC f o r

7

h o u r s a n d q u e n c h i n g i n t o w a t e r .

F i 2

-

Specimen 2 , c o n t a i n i n g 0.&8 w t % Ce. Curve *,by o r i g i n a l d a t a ; C u r v e B , a f t e r a n n e a l i n g a t 9800C f o r 8 h o u r s and quenching i n t o w a t e r ; C u r v e C a f t e r a n n e a l i n g from 910 t o room t e m p e r a t u r e ; Curve P a , a f t e r s u b t r a c t i n g background from c u r v e A ; Curve P c , a f t e r s u b t r a c t i n g background from c u r v e C.

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JOURNAL D E PHYSIQUE

F i g . 3

-

Specimen 3 , c o n t a i n i n g F i g . 4

-

Specimen 4 , c o n t a i n i n g 0.05 w t % Ce. Curve A,by o r i - 0.12 w t % Ce, Curve A,by o r i g i n a l g i n a l d a t a ; Curve P a , a f t e r d a t a ; C u r v e B , a f t e r annealing a t 980 s u b t r a c t i n g brckground from O C f o r 8 h o u r s and quchening i n t o

c u r v e A. water;Curve C , a f t e r a n n e a l i n g from

9lOoC t o room t e m p e r a t u r e ; C u r v e Pa, a f t e r s u b t r a c t i n g background from c u r v e A;Curve P c , a f t e r s u b t r a c t i n g background from c u r v e C.

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454-460.

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S t u d i e s of A p p l i c a t i o n s o f Rare E a r t h t o I r o n and S t e e l . Poking I n s t i t u t e of I r o n and S t e e l Technology, (19781.

/4/ De B a t i s t , R . , I n t e r n a l f r i c t i o n of S t r u c t u r e 1 D e f e c t s i n C r y s t a l - l i n e S o l i d s , Amsterdam ( 1 72)

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7-ICIFUAS (1981). C5-451.

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C5-463, 469.

F i g . 5

-

Specimen 5 , c o n t a i n i n g 0.083 w t % Ce.

Curve A , by o r i g i n a l d a t a ; Curve B, a f t e r s u b t r a c t i n g background from c u r v e A.

1a.e

-

o.e7 0 A .

0.05

0.04,

0.b3

O*l

OD1

1.40 1.35 1.30 I . X S 1.10 1.15 1.10 1.05 1.0. i

.

'