Investigation of Production and Properties of Nodular Cast Iron

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INVESTIGATION OP PRODUCTION AND PROPERTIES OP NODULAR CAST IRON

L I8JM R T COLORADO SCHOOL CF 11INFS GOLDEN, COLQRa W

By V ish w a n a th A » A l t e k a r

ProQuest N um ber: 10781413

All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is d e p e n d e n t upon the quality of the copy subm itted. In the unlikely e v e n t that the a u thor did not send a c o m p le te m anuscript and there are missing pages, these will be noted. Also, if m aterial had to be rem oved, a n o te will ind ica te the deletion.

uest ProQuest 10781413 Published by ProQuest LLC(2018). C opyright of the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States C o d e M icroform Edition © ProQuest LLC. ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 4 8 1 0 6 - 1346

54500

A thesis submitted to the Faculty and the Board of Trustees of the Colorado School of Mines in partial fulfill­ ment of the requirements for the degree of Master of Science.

Vishwanatli A . Altekar

Approved:

54500

Golden, Colorado.

Date

YnflL^f

2. 4 % ,

, 1950.

ACKHOWLEDGMENT It

is

w ith a deep se n se o f g r a t i tu d e

t h a t I w ish to e x ­

p r e s s my i n d e b t e d n e s s t o C l a r k B* C a r p e n t e r , P r o f e s s o r o f M e t a l l u r g y a t t h e C o l o r a d o S c h o o l o f M i n e s , w i t h o u t w h ose *

k in d i n t e r e s t and a b le s u p e r v is io n t h i s seen th e

l i g h t o f day*

w ork c o u l d n o t h a v e

He h a s g i v e n much o f h i s p r e c i o u s

t i m e t o w a r d s t h e s u p e r v i s i o n o f w o rk d e s c r i b e d h e r e i n * I am a l s o

i n d e b t e d t o M e s s r s * E r n i e a n d Boy H i g s o n s o f

th e W e s te rn I r o n F o u n d ry , D e n v e r, and t o M essrs* C . F . C a rd , D* C a r d , a n d C l y d e P e n n y o f t h e C . F . C a r d I r o n W o r k s , D e n v e r* P r e p a r a t i o n o f m o u ld s, tr e a tm e n t o f m e t a l , tre a te d

i r o n was d o n e a t e i t h e r o f t h e

and c a s t i n g o f t h e

tw o f o u n d r i e s *

The m a c h i n i n g o f t h e t e n s ! I t e s t b a r s w as d o n e a t t h e C * P , C a r d I r o n W o rk s t h r o u g h t h e k i n d n e s s o f M e s s r s . Dave C a rd and C ly d e P e n n y , I am a l s o

t h a n k f u l t o M r, C u r t i s D ra k e o f t h e G r i f f i n

W h e e l Com pany o f D e n v e r f o r h i s k i n d h e l p i n t h e w ork* To t h e f o l l o w i n g a c k n o w l e d g e d l e a d e r s

in th e f i e l d o f

n o d u l a r i r o n my t h a n k s a r e d u e f o r t h e i r k i n d I n t e r e s t a n d e n c o u r a g e m e n t i n my w o rk s

P r o f e s s o r A l b e r t De Sy o f t h e

U n i v e r s i t y o f G h e n t , B e l g i u m ; Mr* C h a r l e s K* Donoho o f t h e A m e r i c a n C a s t I r o n a n d P i p e C om pany o f B ir m i n g h a m , A la b a m a ; Mr* T* H , W i e k e n d e n , V i c e P r e s i d e n t o f t h e I n t e r n a t i o n a l ' « H I c k e l C om pany; M r. J* A, F o u r n i e r , C h i e f C h e m i s t i n t h e D e p a r t m e n t o f M in e s a n d T e c h n i c a l S u r v e y s o f C a n a d a , a n d Mr* C* M, O f f e n h a u e r , o f t h e U n io n C a r b i d e C a r b o n R e s e a r c h

L a b o ra to rie s ,

I n c o r p o r a t e d , N i a g a r a F a l l s , New Y ork *

I am a l s o v e r y much o b l i g e d t o P r o f e s s o r s M. C . S m ith a n d S* L* S m i t h o f t h e D e p a r t m e n t o f M e t a l l u r g y , C o l o r a d o S c h o o l o f M i n e s , f o r k i n d l y a c c o m m o d a t i n g t h e w o rk i n t h e i r re s p e c tiv e itie s

la b o ra to rie s ,

and f o r p u t t i n g th e a v a i la b l e

a t ray d i s p o s a l *

r

fa c il­

CONTENTS Pag© In tro d u c tio n

.

P a r t X* S u r v e y of* l i t e r a t u r e

.

1

. . . . . . . . . . . .

4

C h a p te r I* T h e o r i e s on N a d u l l a a t i o n o f G r a p h ite

«

C h a p te r I I , P r o d u c tio n o f N o d u la r G r a p h itic I r o n s

12

In tro d u c tio n •

12

M e th o d s o f M a g n e s iu m A d d i t i o n

• • • • • * •

E f f e c t o f I n o c u l a t i o n .................................... . O ptim um M a g n e s iu m C o n t e n t i n C a s t I r o n

.

12

.

15

• • »

16

E f f e c t o f H o l d i n g Time C h e m istry o f th e I r o n E ffe c t of S ilic o n

18 » • • • . . « • . . •

18

. . . . . . . . . . . . .

20

I n f lu e n c e o f P h o sphorus M anganese S u lp h u r

.

5

. . . . . . . . . .

22

. . . . . . . . . . . . . . . .

25



. •

O th e r* E l e m e n t s

. .

.

.

C a stin g C h a r a c te r is tic s P o te n tia l A p p lic a tio n s

.

.

.

.

.

...............

25

27

. . . . . . . . . .

27

. . . . . . . . . . .

54

E c o n o m ic s o f t h e P r o d u c t i o n

*

C h a p te r I I I , P h y s i c a l P r o p e r t i e s and H e at T re a tm e n t o f N o d u la r I r o n s . » • • . • • • . .



38 44

The T e n s i l e P r o p e r t i e s

44

D u c tility

. . . . . . . . . . . . . . . . .

47

. . . . . . . . . . . . . . . . . .

47

H ard n ess

CONTENTS ( C o n t i n u e d )

Page E nd u ran ce P r o p e r t i e s M a c h ln a b llity W ea r R e s i s t a n c e

♦ .

. .

• . * • .

*•

♦ .. . . .

.



«.

. •.

. • • .. . .

.

, *.

. .

.

.

.

• •.

•*

. . . .

.

.

,.

.*

.4 7

.

T ran sv erse S tre n g th

H e a t T re a tm e n ts

.

. .

E l e c t r i c a l R e sista n c e

W e ld a b ility

.

.

..

. . . . . . .

• • . . .

• .

G ro w th o f N o d u l a r C a s t I r o n

. .

.

.

.

49 51

.

.

51

♦ .

51

.

• .

.

.

52

.5 2

* *

55

M e c h a n i c a l W o rk in g o f D u c t i l e C a s t I r o n s ♦ •

59

B ib lio g ra p h y • . . .

♦ • • . .

• • • • • «



• .

. . . . . . . . . .

♦ .

.

62

p

f a r t XI* E x p e r i m e n t a l W ork . In tro d u c to ry

.

. . . . . .

. ♦ .

,

. . . . . . . . . . . . . . . . . .

1

-'''Ibcpdrim ents. . . . . . . . . . . . . . . . . . . .

6

Sum m ary a n d C o n c l u s i o n s

47

INTRODUCTION T h e r e p e r h a p s w as n e v e r made a m o re e p o c h m a k i n g a n n o u n c e ­ m e n t i n t h e h i s t o r y o f t h e c a s t i r o n i n d u s t r y a s t h a t made b y M o rr o g h a n d h i s a s s o c i a t e s a t t h e P h i l a d e l p h i a m e e t i n g o f t h e A m e r i c a n Foundryraen*© A s s o c i a t i o n o n May 7 , 1 9 4 8 .

On t h a t

o c c a s i o n .th e y a n n o u n ce d a p r o c e s s f o r t r e a t i n g c a s t i r o n produce n o d u la r g r a p h ite

i n t h e tta s c a s t ” c o n d i t i o n .

to

T h is

a n n o u n c e m e n t was q u i c k l y f o l l o w e d b y a s i m i l a r s t a t e m e n t b y W ic k e n d e n o f t h e I n t e r n a t i o n a l N i c k e l Com pany a n n o u n c i n g a s i m i l a r p ro c e s s o b ta in in g s i m il a r r e s u l t s by th e use o f a n ­ o th e r e le m e n t. The h i s t o r y o f th e

c a s t i r o n d ev elo p m e n t c a n be ro u g h ly

d iv id e d in to th re e p e rio d s . f o r w hat i t

I n t h e f i r s t c a s t I r o n was t a k e n

w as w o r t h a n d u s e d a s s u c h ; i n t h e s e c o n d p e r i o d ,

a t t e m p t s w e re made t o i m p r o v e i t s

p r o p e r t i e s by a llo y a d d i­

t i o n s on th e l i n e o f a l l o y s t e e l s ; sta rtin g

j u s t a f t e r W o rld War I ,

and i n th e

l a s t p e rio d

I t was r e a l i z e d

t h a t th e

s t r e n g t h o f th e I r o n d e p en d s upon th e s t r e n g t h o f I t s e s t c o n s t i t u e n t — th e

g ra p h ite fla k e s ;

made t o m o d i f y t h e s h a p e , s i z e ,

w eak­

a n d a t t e m p t s w e re

and d i s t r i b u t i o n o f g ra p h ite r

f la k e s by v a rio u s in o c u la n ts*

P e rh ap s th e m ost Im p o rta n t o f

t h e s e i n o c u l a n t s w as C a l c i u m s i l l c l & e u s e d i n t h e M e e h a n i t e p r o c e s s , w h ic h r a i s e d

th e p r o p e r t i e s o f g ra y c a s t ir o n to an

a p p re c ia b ly h ig h e r le v e l. The m e t a l l u r g i s t h a d l o n g r e a l i z e d

t h a t th e g r a p h ite

flak e © c o n t r i b u t e

t h e m ost to th e w eakness o f th e i r o n by

I n t r o d u c i n g d i s c o n t i n u i t y among t h e m e t a l l i c g r a i n s . a ls o

re a liz e d

t h a t th e b e s t fo rm o f g r a p h ite

w o u l d b© t h a t i n w h i c h i t s

su rface

l e a s t - w h i c h fo rm I s a sp h e re * tem p ere d m a lle a b le i r o n s ,

I t was

in any ir o n

t o v o lu m e r a t i o

Such a fo rm e x i s t i n g

is

th e

In

was s e e n t o e x e r t t h e l e a s t h a r m ­

f u l i n f l u e n c e on th e m e c h a n ic a l p r o p e r t i e s o f th e i r o n ;

it

w a s t h e i d e a l o f t h e m a l l e a b l e I r o n man and a d r e a m o f t h e v

g r a y c a s t I r o n m an. g ra p h ite

The a n n o u n c e m e n t t h a t s u c h a f o r m o f

c o u l d be o b t a i n e d I n i t s

e n t i r e t y i n 11a s c a s t ” c o n ­

d i t i o n b r o u g h t a su d d e n a w a k e n in g I n t h e f o u n d r y I n d u s t r y . I t b ro u g h t a ju b ila tio n

In th e g r a y I r o n fo u n d ry m en , and a p ­

p re h e n s io n am ongst th e m a lle a b le and th e s t e e l fo undrym en. T h at announcem ent to d a y i s te n tio n , research ,

two y e a r s o l d .

The w id e a t ­

a n d a p p l i c a t i o n s t u d i e s t h a t t h i s new

m a t e r i a l r i g h t f u l l y d e s e rv e d , h a s to a c o n s id e r a b le e x t e n t *

rem oved th e a p p r e h e n s i o n s am o n g st v a r i o u s s e c t i o n s o f t h e in d u stry .

I t h a s b e e n r e p o r t e d t h a t m any m a l l e a b l e

fo u n d rie s,

re c o g n iz in g th e s u p e r io r m a te r ia l, have s t a r t e d

p ro d u c in g i t

iro n

a lo n g w ith t h e i r o r i g i n a l p ro d u c t*

A c a r e f u l s t u d y o f t h e p r o p e r t i e s o f t h e new m a t e r i a l r e v e a l s one v e r y im p o r ta n t f a c t — t h a t n o d u la r I r o n h a s a p la c e o f

its

ow n, t h a t I t f i l l s

a g r e a t gap e x i s t i n g b e tw e e n

o rd in a ry c a s t Iro n and c a s t s t e e l .

It

e n jo y s th e p ro c e s s

a d v a n ta g e s o f c a s t ir o n such as c a s t a b i l i t y , w ith th e p ro d u c t a d v a n ta g e s o f s t e e l .

and f l u i d i t y ,

L a te ly as a r e s u lt o f

e x te n siv e a p p lic a tio n t e s t s ,

i t has been re p o rte d th a t in ­

s t e a d o f r e p la c in g any o f th e p r e s e n t c l a s s e s o f f e r r o u s c a stin g a llo y s,

t h e new m a t e r i a l i s

b r i n g i n g n ew b u s i n e s s M e a n w h ile ,

c a p t u r i n g new f i e l d s a n d

to th e fo u n d ry in d u s tr y *

th e p r o c e s s i s b e in g r a p i d l y d e v e lo p e d i n

a l l im p o rta n t f i e l d s .

T re a tm e n t o f b l a s t f u r n a c e m e ta l

d ir e c tly as i t

com es o u t o f t h e f u r n a c e a n d c a s t i n g i t

in g o ts ,

and b i l l e t s

sla b s,

in to

to be s u b s e q u e n tly r o l l e d in to

h e av y s e c tio n s u sed in h eav y i n s t a l l a t i o n s , h a s been p ro p o sed and t r i e d

w i t h some s u c c e s s .

S earch Is

a ls o g o in g on f o r a

b e t t e r m e th o d f o r t h e I n t r o d u c t i o n o f t h e n o d u l l z l n g a g e n t s i n ­ to

th e i r o n and th e o b t a i n i n g o f d e p e n d a b le r e c o v e r i e s .

T h is

I s v e r y i m p o r t a n t f o r p o p u l a r i t y o f t h e m e th o d a s u p o n i t d e ­ p e n d s t h e t r e a t m e n t c o s t and th e e r a d i c a t i o n o f th e c r i t i c i s m th a t i t

i s a “ C ook B ook ” p r o p o s i t i o n .

I n t h e f o l l o w i n g p a g e s a n a t t e m p t h a s b e e n made t o s t u d y c ritic a lly

t h e w ork d o n e t o d a t e o n t h i s

im p o rta n t m a te r i a l.

T he l a t e r p o r t i o n c o n c e r n s I t s e l f

w i t h t h e e x p e r i m e n t a l w o rk

done by th e a u th o r u n d e r th e a b le

su p e rv isio n o f P ro fe sso r

C l a r k B. C a r p e n t e r . th e

su b je c t i s

Y&iereas t h e s u r v e y o f t h e l i t e r a t u r e

e x h a u stiv e ,

h a s b e e n l i m i t e d by th e

on

t h e s c o p e o f t h e e x p e r i m e n t a l w o rk

a v a ila b le

tim e and f a c i l i t i e s .

PART I SURVEY OF LITERATURE

CHAPTER I THEORIES ON NODULIZATIOH OF GRAPHITE It

i s n o t i n t e n d e d t o go I n t o

th e d e t a i l s o f th e v a r i o u s

t h e o r i e s a d v an c ed to e x p la in th e phenom ena r e s u l t i n g I n n o d u ­ la r stru c tu re

in c a s t iro n s.

Such an u n d e r t a k i n g c a n n o t be

j u s t i f i e d on g ro u n d o f i t s v a g u e n e s s an d on th e g ro u n d o f la c k o f c o n v in c in g e v id e n c e To s t a r t w i t h i t

to s u p p o rt th e th e o r ie s #

s h o u l d b e b o r n e i n m in d t h a t t h e r e h a s

b e e n a l a c k o f u n a n i m i t y c o n c e r n i n g t h e m e c h a n is m o f g r a p h i t e fo rm a tio n in o rd in a r y g ra y c a s t ir o n s . tre a tise

A lth o u g h B o y les

on th e s u b j e c t I s v a lu e d f o r I t s e x h a u s t i v e n e s s y e t

t h e d i s c r e p a n c i e s i t n e g l e c t s a r e t o o many a n d o n t h e o t h e r h a n d few o t h e r s e q u e n c e s s u g g e s te d i n th e s o l i d i f i c a t i o n o f th e i r o n s c a n p r o d u c e no l e s s

c o n v in c in g p ro o f i n t h e i r su p ­

p o rt# C o n s i d e r i n g f o r e x a m p le a h y p o e u t e c t i c f i c a t i o n w o u l d p r o c e e d a c c o r d i n g t o B o y le s *

iro n ,

th e

so lid i­

th e o r y i n th e

fo llo w in g seq u en ces: 1.

P rim a ry a u s t e n i t e d rite s ,

f r e e z e s o u t I n th e form o f d e n ­

w h ic h c o n t i n u e

t o g ro w down t o e u t e c t i c

tem ­

p e ra tu re . 2.

C r y s t a l l i z a t i o n o f th e e u te c tic

l i q u i d b e g in s a t

c e n t e r s w h i c h g ro w e q u a l l y I n a l l d i r e c t i o n s f o r m ­ in g a c e l l lik e 3.

stru c tu re *

S e g re g a tio n ta k e s p la c e

I n tw o s t a g e s :

a.

B e tw e e n t h e p r i m a r y d e n d r i t e s a r d

b.

F ro m t h e c r y s t a l l i z a t i o n c e n t e r s o f t h e e u ­ te c tic

4.

in to

th e l iq u i d ,

th e b o u n d a rie s o f th e c e l l .

C o n s t i t u e n t s form ed d u r i n g th e f r e e z i n g o f th e d u t e c ti c occupy th e i n t e r s t i c e s

o f th e d e n d r i t e s .

The g r a p h i t e f l a k e s a n d t h e p h o s p h i d e e u t e c t i c th u s r e s t r i c t e d by th e s iz e

a re

and th e d i s t r i b u t i o n o f

d e n d rite s* 5.

G r a p h i t e f l a k e s do n o t b e g i n t o f o r m u n t i l t h e e u t e c t i c b e g in s to f r e e z e . i s c o m p le te ly f r o z e n , tia lly

c o m p le te .

As s o o n a s t h e e u t e c t i c

th e fla k e

stru c tu re

The f l a k e s g ro w r a d i a l l y f r o m t h e

, c r y s t a l l i z a t i o n c e n t e r s o f th e e u t e c t i c to th e

is essen­

su rro u n d in g l i q u i d ,

re s u ltin g

o u tw a rd i n ­

in to a w ohrl

stru c tu re • M orrogh and W i l l i a m s - ^ h o w e v e r h a v e l i s t e d

42 phenom ena o b -

1 / J o u r n a l o f th e I r o n and S t e e l I n s t i t u t e , v o l . 155, p . 537, 1 9 4 7 . _________________ ___________________________________ _____________ se rv e d In th e m e ta llu r g y o f c a s t i r o n s , p la in e d .

which- a r e y e t u n e x ­

R lle y S / h a s d is c u s s e d th e g r a p h ite

s t r u c t u r e s and

2 / R i l e y , H. L , ; F u e l i n S c i e n c e a n d P r a c t i c e , v o l . 2 4 , p p . 8 -2 4 , 1945. ;_________ _ _ __________ h a s pro v ed t h a t I t h a s l i k e

n a t u r a l and s y n t h e t i c

g ra p h ite s,

a l a y e r e d h e x a g o n a l s t r u c t u r e , w h i c h s h o u l d be g i v e n d u e c o n s id e r a tio n in fo rm u la tio n o f any h y p o th e s is . te re stin g

to

r e c a l l here t h a t c a l c i u m s i l i c l d e

I n d u s t r y 1s m o s t s p e c t a c u l a r i n o c u l a n t b e f o r e

It

is

In ­

- - c a st Iro n

th e d i s c o v e r y

o f m ag n esiu m , h a s b o n a to m s l i e

th is la y e re d hexagonal stru c tu re *

The c a r ­

i n a s e r i e s o f p a r a l l e l s h e e t s In w h ich t h e y

a re a rra n g e d a t c o rn e rs o f s e t s o f r e g u la r hexagons* c a r b o n a to m s I n t h e

la y e rs a re spaced c lo s e ly to g e th e r as

co m p ared w ith t h e s p a c i n g b e tw e e n a d j a c e n t p la n e s * p e rm its e a sy s l i p s

The

T h is

a lo n g t h i s p la n e and a ls o a c c o u n ts f o r

th e m e c h a n ic a l p r o p e r t i e s o f g ra p h ite * R eal I n i t i a t i o n o f th e s tu d y o f th e g ra p h ite

fla k e s

u n d e r m e t a l l o g r a p h w as made p e r h a p s b y M o r r o g h , who b y a n e l a b o r a t e p o l i s h i n g te c h n iq u e n o t o n ly p r e s e r v e d th e g r a p h ite in p la c e b u t a ls o b ro u g h t o u t i t s

p ro n o u n ced a n i s o t r o p i c

-c ry s ta llin e

s tru c tu re *

u s e f u l a id s

I n th e s tu d y o f th e n o d u la r s t r u c t u r e s o f

g ra p h ite *

H is te c h n iq u e s h a v e s e r v e d a s v e r y

W ith t h e s e m eth o d s M o rro g h s t u d i e d t h e d i f f e r e n t

in te rn a l stru c tu re s

In th e g ra p h ite m asses;

and l a t e r ,

w h ile

s tu d y in g th e g r a p h ite s in n ic k e l- c a r b o n and c o b a lt c arb o n s y s te m s , he o b s e rv e d p ro n o u n ce d te n d e n c ie s on th e p a r t o f th e g ra p h ite th e

to n o d u liz e *

K e e p in g th e

B r i t i s h w o rk ers c o u ld d u p l i c a t e

s u l p h u r c o n t e n t low

th e fo rm a tio n o f n o d u le s

by sim p le c r i t i c a l c o o lin g o f th e c a s t I r o n s .

L a t e r W illia m s

w h i l e s t u d y i n g t h e e f f e c t s o f s m a ll a m o u n ts o f a l l o y i n g e l e ­ m en ts o n i r o n c a r b o n a l l o y s c o n f ir m s th e t e n d e n c y o f th e g ra p h ite

t o be p ro fo u n d ly a f f e c t e d by th e p re s e n c e o r a b ­

s e n c e s o f s u l p h i d e s * 1/ 1 / W il l ia m s ; J o u r n a l o f th e I r o n and S t e e l I n s t i t u t e , 1950*

A p ril

The d e l a y I n t h e f o r m a t i o n o f g r a p h i t e d u e t o t h e c a r ­ b i d e - s t a b i l i z i n g e f f e c t o f th e n o d u l iz i n g a g e n ts form s th e b a c k b o n e o f t h e t h e o r y p u t f o r t h b y M o rro g h * w i t h some m o d i f i c a t i o n ,

o t h e r w o rd s

th e m e ta llu rg y o f n o d u liz a tio n

s i m i l a r to t h a t o f th e r a a l l e a b l l z i n g p r o c e s s *

is

The t r e a t e d

i r o n s o l i d i f i e s w h i t e , a n d I n l a t e r s t a g e s t h e m et a s t a b l e c a rb id e s

\sh ich a r e

in g c h a r a c t e r i s t i c

su p e rc o o le d , a re b ro k en u p . o f th e tr e a te d

d i r e c t p ro o f In I t s

su p p o rt*

The s h r i n k ­

iro n i s p e rh ap s th e b e s t

F u rth e r,

s e c tio n s t h i n enough

t o c o o l w h i t e , h a v e u p o n a n n e a l i n g b r o k e n down i n t o n o d u l a r *

g r a p h i t i c o n es w ith a r a p i d i t y t h a t i s n o t c o m p a rab le to a n y m a lle a b llz in g c y c le , ",:t) n t h e o t h e r h a n d e v i d e n c e i s o n r e c o r d , w h e r e n o d u l e s o f g r a p h i t e h a v e sho w n p r o n o u n c e d s e g r e g a t i o n s w hen f o r c e d t o d o so * V

D© S y i / h a s p r o d u c e d l a r g e

in g o ts o f n o d u la r Iro n

De S y , A l b e r t ; C o r r e s p o n d e n c e , M e t a l P r o g r e s s , v o l . N o. 1 , J a n u a r y 1 9 5 0 , p . 7 9 .

a llo w e d to c o o l s lo w ly , tio n o f n o d u le s in

57,

and h a s r e p o r te d p ro n o u n ced s e g r e g a ­

t h e t o p o f t h e m o u ld .

C e n trifu g a l c a s tin g s

show a l a r g e n u m b e r o f n o d u l e s I n t h e I n t e r i o r w a l l ,

and few ­

e r I n th e o u t e r m o st p o r t i o n . ■ A fo u n d r y h a s c o m p lain e d o f t r o u b l e ^ / e x p e r ie n c e d due to th e f l o a t i n g o f g r a p h i t e 2 / K u n i a n s k y , Max; P r o b l a ms I n p r o d u c i n g d u c t i l e The I r o n W o r k e r , F a l l 1949 I s s u e . tre a te d

iro n c a stin g s*

n u c le u s o b se rv e d a t th e

T h is ,

In

c a s t iro n ;

t o g e t h e r w ith th e a p p a r e n t

c e n te r o f w e ll p o lis h e d g ra p h ite

n o d u le s , form s th e backbone o f th e r i v a l th e o r y pro p o u n d ed b y Do S y o f t h e U n i v e r s i t y o f G h e n t ^ #

(S ee P i g .

1 and 2)

V De

Sy; B e lg ia n r e s e a r c h ad v an ces n o d u la r g r a p h ite th e o ry , A m e r i c a n F o tfn d ry m a n , v o l . 1 5 , p . 5 5 , J a n u a r y 1 9 4 9 . ______ R e c e n tly M orroghS / h a s c o n t r a d i c t e d t h i s

t h e o r y on th e

2 / M o r r o ^ 1, K . ; C o r r e s p o n d e n c e , F o u n d r y T r a d e J o u r n a l , v o l . 8 8 , # 1 7 5 1 / p . 5 2 1 , M a rc h 2 3 , 1 9 5 0 . ___________ __________ g r o u n d s t h a t De S y ’ s n u c l e i t h e o r y I s b a s e d o n h y p o t h e t i c a l fa c ts,

th a t th e re i s

no e v i d e n c e f o r t h e e x i s t a n c e o f s u c h

n u c l e i i n m o lte n i r o n ,

t h a t th e c r y s t a l s t r u c t u r e s o f th e

v a r i o u s n u c l e a t i n g s o l i d p a r t i c l e s a re n o t known, and t h a t th e a p p a re n t n u c le u s o b se rv e d a t th e c e n te r o f th e g r a p h ite n o d u le i s n o t an y f o r e ig n m a te r ia l b u t g r a p h ite ow es i t s

e x is te n c e

in g c r y s t a l l i t e s

to

th e g e o m e tr ic a l n a tu r e

its e lf,

and

o f th e r a d i a t ­

of g ra p h ite .

Much w o rk n e e d s t o b e d o n e b e f o r e a n y o f t h e p r o p o s e d t h e o r i e s a t t r a c t m o re a t t e n t i o n .

As t h e y now s t a n d b o t h .

I g n o r e some o f t h e m o s t i m p o r t a n t e x p e r i m e n t a l f a c t s .

Thus

f o r e x a m p le M o rro gh* s t h e o r y d o e s n o t e x p l a i n why c e r t a i n m a g n e s iu m c o m b i n a t i o n s l i k e . M g - C a , M g - T i, M g -Z r s h o u l d n o t p r o d u c e n o d u l a r s t r u c t u r e s e v e n when a p p r o p r i a t e Mg h a s b e e n r e t a i n e d b y t h e a d d e d t o Mg t r e a t e d z a tio n .

I t is

iro n .

ir o n pro v e

am ount o f

C e rta in in o c u la n ts i f

su b v e rsiv e

i n t e r e s t i n g to n o te h e re

to

th e n o d u l i -

t h a t th e

a b o v e men­

tio n e d a g e n ts c o n s i s t o f pro n o u n ced c a rb id e s t a b i l i z e r s s h o u ld a s s i s t th e m ag n esiu m i n

its

and

e f f e c t o f n o d u liz a tio n in -

F ig. 19—P r o n o u n c e d ra d ia l b a n d s in n o d u le , %/g-in. se c tio n o f s te p b lo c k , as-cast. X i t a l etch', x 1000.

F ig. 5—M ic r o s tr u c tu r e o f l/g-in. se c tio n , as-cast. N i ta l e tc h ; x 200.

F i g s . 1 & 2# W e l l p o l i s h e d n o d u l e s o f g r a p h i t e i n ’ a s - c a s t 1 i r o n show th e r a d i a t i n g c r y s t a l l i t e s a t th e c e n t e r o f w h ic h i s th e a p p a r e n t n u c le u s *

s te a d o f s u b v e r tin g such a s t r u c t u r e . and s e p a r a t i o n o f g r a p h i t e h y p e re u te c tic

Then a g a i n f o r m a t io n

i n n o d u la r fo rm o u t o f a m o lte n

l i q u i d p o in t to

th e p o s s i b i l i t y o f th e p re s e n c e

o f n o d u llz in g i n f lu e n c e s u n e x p la in e d by th e c r i t i c a l c o o lin g th e o ry .

The g r a p h i t e

have p e r f e c t l i b e r t y c o o lin g o f th e

s e p a r a t i n g o u t I n m o lte n l i q u i d to

iro n i s

sh o u ld

a ssu m e a n y s h a p e i f o n l y c r i t i c a l to be h e ld r e s p o n s i b l e .

De S y ’ s t h e o r y

o f n u o l e a t i o n c e n t e r s n e e d s m uch e x p e r i m e n t a l e v i d e n c e .

It

a s s u m e s t h a t m o s t o f t h e g r a p h l t l z a t l o n o c c u r s w hen t h e i r o n is

s t i l l m o lte n , and th e g r a p h ite h a s freed o m to

su it I ts e lf

t o t h e c r y s t a l s t r u c t u r e s o f th e n u c l e i w h ic h a r e h e l d r e s p o n ­ sib le

f o r th e n o d u liz a tio n * I t w o u ld b e u n j u s t t o c l i n g t o a n y o f t h e t h e o r i e s o n

su ch s c a n t e v id e n c e s and i n fa c e o f th e f a c t s o f th em .

Ig n o red by each

T h e y s i m p l y r e p r e s e n t tw o a n g l e s o n t h e p o s s i b l e

m ech an ism o f n o d u i l z a t i o n .

A t p r e s e n t m any l a b o r a t i e s ,

and

c o n c e rn s a re a c t i v e l y engaged on th e s tu d y o f n o d u la r i r o n . L e t u s h o p e t h a t s u f f i c i e n t e x p e r i m e n t a l e v id e n c e w i l l be a t o u r d i s p o s a l In th e n e a r f u tu r e

to u n d e r s ta n d t h i s m ajo r

phenom ena o f th e m odem m e t a l l u r g y .

CHAPTER I I PRODUCTION OF NODULAR GRAPHITIC IRONS In tro d u c tio n In tro d u c tio n o f c e r ta in su ita b le

e le m e n ts I n to

th e c a s t ir o n o f

c o m p o sitio n j u s t b e fo r e p o u rin g p ro d u c e s n o d u la r

stru c tu re .

C e r i u m was t h e f i r s t

th is p u rp o se.

t o be s u c c e s s f u l l y u s e d f o r

No a t t e m p t s w i l l be mad© her© t o d i s c u s s i n

d e t a i l th e p ro d u c tio n te c h n iq u e s in v o lv in g th e u se o f t h i s e le m e n t — e x c e p t f o r c o m p a ris o n w ith i t s

r i v a l m e th o d u s i n g

m ag n esiu m . Us© o f m a g n e s iu m i n

th e fo rm o f a l l o y s , m e ta l, o r v a p o rs

w as f i r s t p u b l i c l y a n n o u n c e d b y t h e I n t e r n a t i o n a l N i c k e l Com** pany* th e

E x t e n s i v e e x p e r i m e n t s h a v e s in e © b e e n made t o d e v e l o p

t e c h n i q u e o f m a g n e s iu m t r e a t m e n t w i t h a v i e w t o o b t a i n

o p tim u m r e s u l t s

w i t h l e a s t m a g n e s iu m a d d i t i o n s . M e th o d s o f Mamie s l u m A d d i t i o n

M a g n e s iu m w i t h I t s b o i l i n g p o i n t w e l l b e l o w t h e u s u a l ta p p in g te m p e ra tu re s o f c a s t ir o n s im m e d ia te ly tu r n s In to g a s e o u s s t a g e w hen i t

I s in tro d u c e d in to

th e m e ta l.

T h is con

v e r s i o n I s s o r a p i d t h a t u s e o f pur© m a g n e s iu m o r h i g h m ag­ n e siu m a l l o y s

I s a tte n d e d w ith r e a c tio n o f e x p lo s iv e v io le n c e

B e sid e s th e d a n g e r in v o lv e d , th e

l o s s o f m e t a l a n d t h e lo w

r e c o v e r y o f m a g n e s iu m i n i r o n h a v e made t h e f o u n d r y m e n s e e k fo r b e tte r a llo y s .

S u g g e s t i o n s h a v e b e e n made o f i n t r o d u c ­

t i o n o f p u r e m a g n e s iu m s t i c k s w i t h a n i m m e d i a t e u s e o f a p r o ­

t e c t i v e hood o v e r th e l a d d i e ^ y

and p r o p e r p r e c a u t i o n s f o r

D o n o h o , C» K.: P r o d u c i n g n o d u l a r i r o n w i t h m a g n e s iu m , A m e r i c a n F o u n d r y m a n , v o l . 1 5 , p . 3 3 , F e b r u a r y 1 9 4 9 . ______

.e x h a u s tio n o f v a p o rs*

T h i s m e th o d h a s b e e n s u g g e s t e d i n l i e u

o f d i l u t e d m ag n esiu m a l l o y s w here l a r g e

a m o u n ts o f d i l u t i n g

e l e m e n t s I lk © c o p p e r o r n i c k e l — u s u a l l y f o u r t i m e s t h e a m o u n t o f m a g n e s iu m — A v e ry e x te n siv e g / Op. G it.-., p .

have to be pu rch ased * r e p o r t h a s b e e n made b y D o n o h o ^ o f

32.

t h e A m e r i c a n C a s t I r o n P i p e C om pany o n t h e t r i a l s in se a rc h o f a s u ita b le p roved t h a t d e c re a se

m a g n e s iu m a l l o y .

c o n d u c te d

H is e x p e r im e n ts

In v io le n c e and in c r e a s e

In re c o v e rie s

can be o b ta in e d by th e u se o f d i l u t e d a l l o y s .

D onoh o*s o b ­

s e r v a t i o n s h a v e b e e n a t t a c h e d h e r e i n a t a b u l a r fo rm *

(S ee

T ab le 1) S i n c e t h e n m any w o r k e d

have e x te n s i v e l y s tu d ie d th e

a g e n t s fro m t h e p o i n t o f v ie w o f r e c o v e r y o f m ag n esiu m .

The

3 / HoldQm an a n d S t e a r n s t V a r i a b l e s i n p r o d u c i n g n o d u l a r i r o n , A m e r i c a n F o u n d r y m a n , v o l . 1 6 , p . 3 6 , A u g u s t 1 9 4 9 .__________ f i g u r e s o n r e c o v e r y v a r y fro m 5 p e r c e n t t o 90 p e r c e n t w ith th e

ty p e o f a l l o y u s e d .

I t Is

im p o rta n t h e re to r e c a l l th e

c o n s u m p t i o n o f m a g n e s iu m b y s u l p h u r , a n d t h e r e c o v e r y f i g u r e s q u o te d a re su lp h u r.

a f t e r a llo w in g f o r th e

l o s s o f m a g n e s iu m t h r o u g h

A g e n e r a l fo rm u la

Per cen t reco v ery

-

B

S

K

,t ,

P r ? .* ? ..* , A , § .

% a d d i t i o n o f m a g n e s iu m

TABLE I. Effect of Adding Magnesium Alloys to High Carbon—Low Phosphorus Irons

Heat No.

TC

1-329-1 -2 -3

4-C5 418 413 406 3-94 3-90 3-93

2-33 2-21 2-61 2-39 3-00 2-91 2-56

0-037 0-043 0-040 0-040 0-064 0-046 0-048

0-59 0-58 0-60 0-57 1-05 1-19 1-00

0-07 — — ■— 0-11 — —

418 416 414 3-96

1-58 1-78 2-02 1-68

0-044 0-043 0-047 0-047

0-71 0-71 0-78 0-69

0-16 —

1-370-1 -2 -3

3-57 —

2-20

0-027

0-64 —

1-410-1 -2 -3

3-62 __ —

2-61

0-55





1-374-1 -2 -3

3-71

1-87

0-030









1-404 1 -2 -3

3-44

2-19

0-040

0-62

___

___









1-402-1 -2 -3 -4

3-70

1-82

0-60

-4 1-330-1 -2 -3 1-340-1 2 -3

-4

___

Si*

— .

___

____

___

S

____

0-048 .___

___ .

___

_

0-045







Mn

P

Magnesium. 0/o

Form of Magnesium

Ni-Mg 50-50 Ni-Mg 50-50 Ni-Mg 50-50 Ni-Mg 50-50 Zr-Mg 40-60 Ni-Mg 50-50 Ti-Mg 50-50

Alloy Alloy Alloy Alloy Alloy Alloy Alloy

Added

Anal.

(>■25 0-38 0-50 0-63 0-50 0-50 0-50

0-125

25 3N Slow C ooled

A . v n k a f f n c ;

c m

A

n

a m m

: a i ,i ;d

Y ield Strength, psi

I 1 1.000 1 1 3 .1 0 0 90,700 1 0 0 ,1 0 0 7 7.7 0 0 7 8 ,3 0 0 7 1,500 7 1,900 7 1 ,0 0 0 7 1 ,7 0 0 08,900 09,100

c a f

7 5 ,8 0 0 7 7 ,1 0 0 0 8,200 7 3 ,1 0 0 5 1,000 5 1 ,5 0 0 5 3 ,0 0 0 5 1 ,0 0 0 19,500 5 1 ,5 0 0 19,800 19,500

T

i m

k

a \ d

P r o i m . r t i i :s I s o t i i i .r m

a

i

A m o f

o f . v i

, \ o d i

o f

f a r

.i .v

F .lo n ga - R e d . o f B r in e l ! Am ount tion. A rea, H a rd n ess P earlite, P e r C e n t P e r c e n t N u m b e r P e r cei 1 1 0.5 5.5 8.0 7.5 20 .5 22 .0

1.0 3.5 0.3 5.1 2 1 .0 2 1 .0

2 0 .0 2 3 .0 2 3 .0 2 7 .0 28 .0

2 0 .2 2 1 .0 2 0 .8 3 0.3 3 0 .9

229 229 197 197 197 197 179 179 179 179 107 107

_

07 .0 1 1.8 10.0 1 1.0 /. / 0 ,-f

T a b l e V I .— Influence of Section Size and Thermal Treatment on Nodular Irons. H igh-strength iron.

1 Tensile Yield p o in t, 1 stre n g th , tons per tons p er sq. in . sq . in .

Therm al tre a tm e n t.

Elonga- | Reduction tio n , j in area, per cent, per cent. on 2 in.

E lasticity , X 1061b. p er sq. in.

Im p act, ft.-lb.

Yield point, to n s per sq . in .

Tensile strength, tons per sq . in.

Elonga­ tio n , ' per cent, on 2 in.

R eduction in area, [ B .H .N . per cent.

E la s tic ity ,; Im pact, x 106 l b . | per sq. in. | ft.-lb.

269 262 241 229 229

23.0 23 .0 23 .6 22.7 23.5

39

23 .6 2 3 .3 17 .8 1 6 .9 1 4 .0

33.3 32.1 22.7 20.1 18.3

11.0 7 .5 2 .0 3 .0

8.8 7.5 1.8 1.2 1 .0

187 187 175 148 141

22.1 22 .3 19.7 18.8 17.4

3 .0 3 .2 2 .0 2 .0 1.5

2 .5 2 .2 1 .5 1 .0 1 .0

229 197 197 217 212

22 .8 21.5 23 .6 22 .2 22 .8

186

2 1 .8 2 1 .2 16 .4 16 .6 14 .8

29 .5 28.3 21 .5 19.1 17.8

17.2 12.5 4.5 3 .0 2 .0

15.0 11.0 3.0 1 .5 1.2

163 163 148 144 138

->-j •> 2 1 .9 20 .1 18.8 18.3

35 .1 3 2 .0 31 .1 2 9 .6 2 9 .9

7 .0 8 .0 3 .5 3 .0 4 .0

4 .5 5 .5 2 .5 2 .0 2 .8

187 179 183 183 183

22.4 21.7 23.1 22.4 22.3

2 0 .3 19.1 15.2 15.4 15.2

2 8 .3 , 2 0 .9 19.7 18 .4 16.3

19.0 14.5 4 .0 3 .0 2 .0

16.0 13.8 • 3 .0 1.8 1.0

148 143 134 131 128

-F I 20.7 17.8 17 .0 17.0

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3 .0 3 .2 1 .8 1 .5 1 .8

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269 269 262 255 255

2 1 .9 22.5 21.9 23.1 22.8

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47.0 45.5 87.2 29.8 28.1

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2 / T s u n K o i G r o w th o f N o d u l a r c a s t i r o n , F o u n d r y T r a d e J o u r n a l , v o l . 8 8 , no* 1 7 5 5 , p . 4 3 3 , A p r i l 2 0 , 1950* and n o d u la r ir o n to

c o m p a re t h e g r o w t h .

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a f t e r 27

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The m e t a l l o g r a p h i e e x a m i n a t i o n show ed e x t e n s i v e o x ­ The n o d u l a r I r o n a f t e r r e p e a t e d h e a t i n g h a d g ro w n

o n ly 3 p e r c en t* th e p e a r l i t i c

F u r t h e r m o r e t h e r e w as no m a r k e d c h a n g e o f

m a t l ^ , ' ^ x c e p t a t t h e r i m w h e r e some d e c a r b u r i -

s a tio n had o ccu rred . He a l s o

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h o u r s and o b s e rv e d 0 . 6 p e r c e n t g ro w th i n o r d i n a r y g ra y and 0 .4 p e rc e n t in n o d u la r c a s t I r o n s . sh o w s t h e

r e s u l t s o f T s u n K b.

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Number o f Cycles (M h r a t