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WELDING RESEARCH

S U P P L E M E N T T O T H E W E L D I N G J O U R N A L , M A R C H , 1 98 0

S p o n s o r e d b y t h e A m e r i c a n W e l d i n g S o c i e t y a n d th e W e l d i n g R e s e ar c h C o u n c i l

l l

D r

Effect of Manganese on the

Microstructure and Proper t ies of

A l l -We ld -Me ta l Depos i t s

Going from 0.6 to 1.8 Mn increasingly refines weld

microstructures and promo tes acicular ferrite formation,

and optimal impact is attained with approxima tely 1.5%

Mn although strain aging affects notch toughness and

displaces optimum Mn to a higher concentration

BY G. M. EVANS

The ef fect of manga nese,

1.8 , on t he m ic ro -

2560)

ten

2

er 0.1% Mn add i t ion t o t he depos i t .

Charpy V, Schnadt and C O D tests

s -d epo s i t ed we ld meta ls in

ct prope r t ies bein g at ta ined at a

only a margin al e f fect on impa ct

marked ly a f f ec ted no tch t ough

ess and d isp laced the op t imum m a n

T h e wo r k i n g p r o g r a m o f S u b c o m -

o f t he I n te rna t iona l Inst i

W el di ng cal ls for a jo in t e f for t

t o s tudy t he m ic ros t ruc tu re o f we ld

meta l .

As a f i rs t s tep, four a l l - we ld

meta l depos i t s have been d is t r ibu ted

to va r ious labora to r ies w i t h recom

mendat ions ' f o r t he charac te r iza t ion

of the microstructural c o m p o n e n t s .

The present paper deta i ls the f i n d

ings of the Swiss delegat ion in co l labo

ra t ion w i t h t he W e ld ing I ns t i t u te

(Un i t ed K ingdom) . I n add i t ion t o t he

me tal log raph ic s tudies , a test program

was conduc ted t o eva lua te t he in

f luence of manganese on the tens i le

and impact proper t ies of the

w e l d

ments.

E x p e r i m e n t a l P r o c e d u r e

Electrodes

Four expe r imenta l i r on pow der t ype

basic e lect rod es, cod ed A , B, C and D,

Paper to be presented at the AW S 61st

Annual Meeting in Los Angeles, California,

during April 14-18, 1980.

G. M. EVANS is Chief Metallurgist, Weld ing

Industries Oerlikon Bueh rle Ltd., Zurich,

Switzerland.

were prepared us ing 4 mm (0.16

in.)

d iame te r co re w i re . The fe r ro -man ga-

nese contents of the coat ings were 3,

5, 7 and 9%, respect ive ly , and th e fe r ro-

s i l i con con ten t was ba lanced . The

coat ing factor was 1.70 and the e lec

trodes were baked for 1 h at 400°C

(752°F) to y ie ld a d i f fus ib le hyd roge n

content of 2 .3 ml/100 g deposi t ,

accord ing t o t he ISO procedure . -

Weld Preparation

The we ld p repara t ion emp loye d was

that spec i f ied in the Intern at ion al

Standard for the code of symbols for

manual meta l arc e lect rodes, namely

ISO 2560-1973.

Weld ing was done in t he f la t

pos i

t ion us ing the s t r inger bead technique.

Direct cur rent (e lect rode posi t ive) was

employed , t he amperage be ing 170 A,

the vo l t age 21 V and the hea t - inpu t

n o m in a l l y 1

k j / m m .

The in ter layer

tem pe ratu re w as 150° C (302°F).

Heat Treatment

The we ldments were t es ted in bo th

the as-welded and the s t ress- re l ieved

W E L D I N G R E SE A RC H S U P P L E M E N T I 67-s



Table 1-VVeld Metal Composit ion (As-Welded), Wt-%

Electrode C Mn Si S O

A

B

C

D

0.035

0.038

0.049

0.051

0.66

1.00

1.42

1.82

0.30

0.30

0.34

0.34

0.006

0.005

0.005

0.006

0.013

0.014

0.013

0.017

0.007

0.010

0.009

0.009

0.049

0.046

0.041

0.039

(2 h/580°C or 2 h at 1076°F) co nd i t io n.

Impact tests (Charpy V notch) were

a lso conduc ted on s t ra in aged spec i

mens , compressed 10% and aged fo r

Vz

h at 250°C (482°F).

Mechanical Testing

Two sub-s ize a l l -we ld -meta l t ens i le

spec imens (M in i t r ac ) were mach ined

and tested for each type of e lect rode

and cond i t ion . A lso approx imate ly 35

Charpy V no tch spec imens were

st ruck, so as to obta in the complete

t rans i t ion curve.

Schnadt impact specimens

3

we r e

prepared f rom as -we lded depos i t s and

were t es ted under b radycoheracy (B„)

and tachycoheracy (K„) cond i t ions . I n

a d d i t i o n ,

as -we lded p la tes were C O D

tested in ful l thickness (20 mm or 0.79

in . ) a t t he We ld ing I ns t i t u te . The we ld

metal was saw notched (0.15 mm or

0.006 in . ) t ransversely to prov ide sub

s id iary- type specimens, as proposed in

D D 19 bu t w i t ho u t a f a t igue c rack .

Resul ts

Chemical Composition

Typical chemical analyses of the

deposi ts are g iven in Table 1. The

systemat ic increase in the amount of

fer ro-manganese in the coat ing re

sul ted in four d is t inct weld meta ls

conta in ing, nominal ly , 0 .65, 1.0, 1.4

and 1.8% Mn.

The we ld s i l i con con ten t was re la

t ive ly constant , but the carbon and

phosphorus con ten ts inc reased p ro

gress ive ly over the range. Weld meta l

oxygen leve l , on t he o ther h and ,

decreased, thus substant ia t ing the

deox ida t ion po ten t ia l o f manganese .

Essen t ial ly the same resu lts as give n in

Tab le 1 were ob ta ined on repea ted

analysis for the stress-relieved sam

ples.

Metallographic Examination

General. A t ransverse sect ion of one

o f the m u l t i - r u n depos i t s is show n in

Fig. 1, a to ta l o f n ine layers b eing

required to f i l l the gap. Three beads

were deposi ted per layer , and the

mac roscop ic ef fect was of repeated

sequences of as-deposi ted and super-

c r i t i ca l l y hea t -a f f ec ted we ld meta l

zones.

The w id ths o f t he co lumnar , coarse

gra ined and f ine gra ined regions were

measured in the ver t ica l mid-p lane

pos i t ion and the dup l ica te resu l t s ,

ob ta ined by examin ing as -we lded and

st ress- re l ieved specimens, are de

p ic te d in F ig. 2 . The pe rcentages o f the

Fig. 7—Cross section of multi-run depos it

5 -

LU

U_

O

LLI

o

<

LL

CC

ID

CO

Q .

O

s

o

LL

10

15

LLI

o

< 2 0

l -

cn

a

co lumnar

coarse

, I fine

g ra ined Jg ra ined

Plate

sur face

E

E

o

.c

u

>

o.

O

.c

O

• - S T R E S S - R E L I E V E D

Fig. 2 —Zone distribution along the vertical centerline position

Table

2—Zone

Percentages in the Equivalent

ISO-V

Notch Position (AW = As-Welded,

SR = Stress-Relieved)

Z o n e

C o l u m n a r

Coarse g ra ined

F ine g ra ined

A W

18

35

47

SR

32

24

42

A W

23

34

43

SR

19

35

46

A W

22

34

44

SR

12

37

51

A W

11

34

55

SR

20

37

45

Average

20

34

46

68-s l

M A R C H 1 9 80



>: :;K> m

J H

of top heads (co

35 on reproduc

US

HP

V '

im.^MmM^iMmiM

Fig. 4—Photomicrographs of coarse grained

regions. X200 (reduced 35 on reproduc

tion)

..

•w t ' J S V ' * ' ••

V

••'••' i

F/g. 5—Photomicrographs of fine graine d

regions. X.315 (reduced 35 on reproduc

tion)

The w id th o f t he co lumnar reg ions

the va lues f o r dup l ica te spec i

ens scat ter ing to an equivalent

of the coarse and f ine gra ined regions

a t t he no t ch loca t ion was f ound to be

80%.

A s ligh t ve r ti ca l d isp lace men t

wou ld a f f ec t t he re la t i ve p ropor t ions

of the zones, s ince the low er runs

t e n d e d t o c o n t a i n w id e r c o l u m n a r

bands.

The co lumnar g ra ins b roadened as

the we ld p rogressed dur ing depos i

t i o n , due to t he ep i t ax ia l g rowth

e f f ec t . As an approx imat ion , however ,

i t can be presumed that the sequence

is repe t i t i ve t h ro ug hou t and tha t t he

cent ra l top bead and the adjacent

heat -af fected weld meta l serve to

character ize the bulk of the deposi t .

Typica l microst ructures of the four

manganese-con ta in ing we ld meta ls

are shown in Figs. 3, 4, and 5, for the

columnar , coarse gra ined and f ine

gra ined regions, respect ive ly .

Columnar Region. The top ce nt ra l

bead of each specimen was examined

a t X200 and quan t i t a t i ve me ta l log ra ph

ic meas ureme nts were m ade as de

scr ibed in Doc. I I -A-389-76

1

, using a

W E L D I N G R E SE A RC H S U P P L E M E N T I 69-s



Fine grained

100

9 0

Fig. 6—Diagram of top bead and adjacent areas

Swif t po int counter . The area t raversed

measured 2.5 X 2.0 mm- (Fig. 6), and

500 poin ts were re corde d by each of

two invest igators.

T h re e m a jo r m i c r o s tr u c t u r a l c o m p o

nen ts (F ig . 3B) were iden t i f ied , nam e-

ly:

1. Pro -eu tec to id f e r r i t e ( l igh t e t ch

ing).

2. I n te rmed ia te lame l la r p rodu c ts ,

main ly fer r i te s ide p lates resembl ing

upper ba in i t e ( l igh t e t ch ing) .

3. Ac icu la r fer r i te , con sis t ing of a

f ine s t ruc tu re o f in te r lock ing f e r r i t e

p la tes (dark .e t ch ing) .

The resu l t s ob ta ined on po in t coun t

ing are plot ted in Fig. 7. I t can be seen

that the amount of ac icu lar fer r i te

increased markedly , a t the expense of

p ro -e u tec to id f e r r i t e , as t he m anga

nese content increased. Also, a c lear

t rend ex is ted for the in termediate

lame l la r component t o dec rease w i t h

increasing manganese.

Carbon repl icas of the top beads

we r e e x a m in e d a t t h e W e ld i n g Inst i

t u t e ,

in a t r ansm iss ion e lec t ron m ic ro

scope (TEM), and a l inear in tercept

method was app l ied a t a magn i f i ca t ion

of X2500. The results are given in Table

3, the values for the h igh manga nese

we lds be ing ind ica t ive o f t he ac icu la r

Table 3—Average Linear Intercept in Top

Beads of As-Welded and Stress-Relieved

Specimens

Average linear intercept,

jtm

Electrode

A

B

C

D

As

-depos

3.30

2.87

1.72

1.05

ted St

r

ess-relieved

3.96

2.60

1.70

1.59

ferr ite lath size.

Examina t ion o f t he rep l i cas showed

that there was a gradual t rans i t ion

be tween ac icu la r f e r r i t e and p ro -

eu tec to id f e r r i t e . A lso , t he d is t inc t ion

norma l ly made be tween the two

mic ros t ruc tu res in t he op t ica l m ic ro

scope was pure ly arb i t rary at h igh

m a g n i f i c a t i o n .

Smal l and widely d ispersed areas of

re ta ined aus ten i t e were observed on

the repl icas. The amount of austeni te

inc reased w i t h inc reas ing manganese

but only in the case of weld D was

suf f ic ient austeni te present (1%) to be

de tec ted by X- ray d i f f r ac t ion .

Al l

the

repl icas f rom st ress- re l ieved welds

cou ld be read i ly d is t ingu ished by t he

presence of gra in boundary carb ides

• ~AS WELDED

O-STRESS-flELIEVED

ACICULAR

FERRITE (3)

PRO-EUTECTOID

FERRITE (1)

0 5

K) 1-5

MANGANESE IN W E L D , .

Fig. 7—Effect of manganese on microstruc

ture of top bead

wh ic h we r e f o r m e d b y t h e t e m p e r i n g

out of the reta ined austeni te.

Any mar tens i t e wh ich m igh t have

fo rmed w i t h in t he re ta ined aus ten i t e

was d i f f ic u l t to detec t because of the

f ine scale of the s t ructure. Such ind ica

t ions o f mar tens i t e , as were f ou nd ,

were of considerably smal ler areas

than those repor ted by Gar land and

K i r k w o o d

5

as occu r r ing in submerge d

arc welds. Fur thermore, i t was not

poss ib le to ident i fy the areas as e i ther

la th or twinned mar tens i te or to assess

them quan t i t a t i ve ly .

Coarse Grained Region. P h o t o m i

crographs of the reheated weld meta l

t aken d i rec t ly be low the cen t ra l t op

bead are sho wn in Fig. 4 . W ith increas

ing manganese the s t ructure became

inc reas ing ly more dark e t ch ing , and

the p ro -eu tec to id f e r r i t e de l inea t ing

the pr ior austeni te gra in boundar ies

wh ich became f ine r and hence tended

to accentuate the coarse gra ined

na tu re o f t he zone . The fus ion bound

ary in the case of the lowest manga

nese w el d (A) was d i f f ic u l t to locate

microstructurally

but the segregat ion

bands ( r ipp les) could readi ly be seen

by vary ing the focus.

7

E

Q 5

O

O 1

As

1

deposited region.

Reheated region.

-

/

y y

X

^ ^-'

,

y-

W.I.

A .

J

-

/

C ,

..-

A

y- -

--'

0 200 400 600 800 1000

NUMBER OF GRAIN BOUNDARIES INTERCEPTED .

Fig.

8—Grain

boundaries intercepted on

traversing as-deposited and reheated re

gions

Table 4—Linear Intercept Results From Fine Grained Region

(H

= hor izontal,

V = vertical)

I n te rcep t

per mm

155

146

Rat io

1.06

I n t e r c e p t / m m

150

a

s

c

Interval / (fi)

6.7

P'

/2

, m m '-'

12.22

B

C

D

H

V

H

V

H

V

173

171

199

208

237

253

1.01

0.96

0.94

172

203

245

5.8

4.9

4.1

13.13

14.28

15.62

70-s I M A R C H 1 9 8 0



T h e m i c r o s t r u c t u r e w i t h i n t h e p r o -

c t o i d f e r r i te e n v e l o p e s a p p e a r e d

o p t i c a l l y i d e n t i c a l t o t h e a c i c u l a r

o c c u r r i n g in t h e a s - d e p o s i t e d

e l d m e t a l . T h e a r ea s s u r r o u n d e d b y

p r o - e u t e c t o i d f e r r i te d i f f e r e d i n

i ze a n d t h e b o u n d a r y o f t h e c o a r s e

e d z o n e w a s d i f f i c u l t t o l o c a t e ,

i n c e t h e m i c r o s t r u c t u r e t e n d e d t o b e

e p e n d e n t o n t h e u n d e r l y i n g s o l i d i f i

t r a n s f o r m a t i o n p a t t e r n .

l a tt e r p h e n o m e n o n w a s p a r t i c u

l a r ly n o t i c e a b l e a t t h e p e r i p h e r y o f t h e

o p b e a d w h e r e t h e h e a t - a f f e c t e d

o n e w e l d m e t a l ha d t r a n s f o r m e d

a c k i n t o c o l u m n a r t y p e g r a i n s . A l s o ,

i n t e r a c t i o n o c c u r r e d b e t w e e n super

i m p o s e d h e a t - a f f e c t e d z o n e s , a t y p i c a l

o c c u r r e n c e b e i n g t h e c o n t i n u a t i o n o f

a f i n e g r a i n e d r e g i o n i n t o a c o a r s e

g r a i n e d r e g i o n at t h e p o i n t o f i n t e r c e p

t i o n w i t h a n e w f u s i o n b o u n d a r y . T h e

d e p o s i t i o n s e q u e n c e , h o w e v e r , w a s

s u c h t h a t o v e r l a p p i n g o f h e a t - a f f e c t e d

z o n e s d i d n o t o c c u r at t h e C h V - n o t c h

l o c a t i o n .

T h e s c a n n i n g e l e c t r o n m i c r o s c o p e

( S E M ) w a s u s e d at t h e W e l d i n g

I n s t i

t u t e t o s t u d y t h e a s - d e p o s i t e d a n d

r e h e a t e d r e g i o n s o f t h e w e l d m e n t s . A

l i n e a r i n t e r c e p t m e t h o d w a s a p p l i e d

a n d t h e r e s u l ts o b t a i n e d f o r a s - w e l d e d

s p e c i m e n s a r e g i v e n i n F i g . 8 , t h e

c h a n g e in i n t e r c e p t b e i n g m o n o t o n i c

w i t h i n c r e a s i n g m a n g a n e s e . T h e f u s i o n

b o u n d a r i e s w e r e c l e a r l y v i s i b l e , a n d

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

l i n e a r i n t e r c e p t w h e n t h e b o u n d a r i e s

w e r e c r o s s e d . T h e b o u n d a r i e s b e

t w e e n t h e i n t e r c r i t i c a l l y a n d f u l l y

r e h e a t e d r e g i o n s , h o w e v e r , c o u l d n o t

b e l o c a t e d b y d i r e c t o b s e r v a t i o n , n o r

w e r e t h e y d e t e c t e d b y t h e i n t e r c e p t

m e a s u r e m e n t s ( F i g . 8 ) , s i n c e l i t t l e o r

n o d i s c o n t i n u i t y o f s l o p e o c c u r r e d

w i t h i n th e r e h e a t e d r e g i o n s .

Fine Grained Region. T h e f i n e

g r a i n e d r e g i o n s ( F ig . 6 ) w e r e p h o t o

g r a p h e d a t X 6 3 0 , a n d l i n e a r i n t e r c e p t s

o f g r a i n b o u n d a r i e s w e r e m a d e a s

d e s c r i b e d i n D o c . I I - A - 3 8 9 - 7 6 . T h e

r e s u l ts o b t a i n e d f o r t h e v e r t i c a l

( t h r o u g h - t h i c k n e s s ) a n d t h e h o r i z o n

t a l d i r e c t i o n s a r e g i v e n i n T a b l e 4 a n d

s h o w a f a ir d e g r e e o f e q u i a x i a l i t y .

T h e r e c i p r o c a l o f t h e s q u a r e r o o t o f

t h e m e a n g r a i n i n t e r v a l is p l o t t e d ,

a g a i n s t w e l d m e t a l m a n g a n e s e c o n

t e n t , i n F ig . 9 . A s t r a i g h t - l i n e r e l a t i o n

s h i p w a s o b t a i n e d , m a n g a n e s e a g a i n

b e i n g f o u n d t o h a v e a m o n o t o n i c

i n f l u e n c e . O f p a r t i c u l a r i n t e r e s t is t h a t

t h e p r e s e n t g r a i n s i ze m e a s u r e m e n t s

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

t h o s e r e p o r t e d b y T u l i a n i

6

f o r r e h e a t e d

r u n s o f s u b m e r g e d a rc w e l d m e t a l .

M e ch a n i ca l P r o p e r t i e s

Tensile Results. T h e t e n s i l e t e s t d a t a

o b t a i n e d a r e g i v e n i n T a b l e 5 f o r b o t h

t h e a s - w e l d e d a n d s t r e s s - r e l i e v e d c o n -

5 0 5

1 0 1-5

M A N GA N E S E IN W E L D ,

2 0

Fig. 9—Effect of mang anese on the mean linear grain intercept (fine grained

region)

T a b l e 5-Tensile Test Resul ts

1

1

C o n d i t i o n

A s - w e l d e d

Stress-re l ieved

Electrode

A

B

C

D

A

B

C

D

YS

392

413

468

514

370

402

436

479

N/mm

1

UTS

466

498

551

588

456

490

529

576

°c

El

31.9

31.2

29.4

28.0

35.2

31.0

31.6

27.4

RA

80.6

80.6

78.7

76.8

80.6

80.6

78.8

76.9

11

YS—yield s t r e n g t h ; UTS—ultimate t e n s i l e s t r e n g t h ; E l — e l o n g a t i o n ; RA—reduction in area.

E

z

c/)

6 0 0

5 5 0

SOO

4 5 0

4 0 0

3 5 0

1

A

^W

y

- &

• /

y

P-

y

y

y

y

1 1 1

B C J ^ U X S . -

y &

y^ s

^y s

y^s'

y '

Y.S.

y

*'

y^ y

s y

.— y —

y

y^ y

/ • y '

s * * • A S W E L D E D

O S T R E S S - R E L I E V E D

1 1 1

0 - 5 1 0

1-5

2 0

M A N G A N E S E I N W E L D , % .

Fig. 10— Effect of man ganese on the tensile properties of multi-run deposits

W E L D I N G R E S E A R C H S U P P L E M E N T I 71-s



2 5 0

2 0 0

^150

aa

UJ

5

1 0 0

a

UJ

DO

a

o

S2 5 °

CO

<

A

B

C

D-

I I I I

C h a r p y

- ' ' / /

/ / /

1

i:

If \

/ / /

/

/ •', /

• / • ' • /

/

-yy

i i i i

i

- V

fy

i

i

.-——

i

- 8 0 - 6 0 - 4 0 - 2 0 0 2 0

T E S T T E M P E R A T U R E , °C .

Fig. 11—Charpy

V-notch

impact results (as-welded)

3 0

2 0

E

a

10

4 0

^

3 0

> •

a

tr

UJ

UJ

2 0

Q

UJ

m

cr

8

10

CO

<

0

I

A

B

C

D

i

I I I I I

S c h n a d t ,

K

0

y_

,yy

.• j

/ • ' n

/•'

/

/ 1

i i

i

1

y

/in

1 i

*

•/My

-y

i i i i

-

_

- 1 5

10

E

a

- 5

-80 -60 -40 -20 0 20

T E S T T E M P E R A T U R E , ° C .

Fig. 13—Schnadt impac t test results K„ (as-welded)

1 2

1 0

E

E

^ S

a

o

o

<

o

on

o

0-8

0 -6 -

0-2

I I

A

_ B

c

D

| COD

-

-

..- y

.I I

I

clip

f

>' /

/

'/ y

gauge

I

l im i t .

I

-

-

-

- 2 0 0

-150 -100

T E S T T E M P E R A T U R E ,

Fig. 12-COD test results (as-welded)

d i t i o n s . Y i e l d s t r e n g t h a n d u l t i m a t e

t e n s i l e s t r e n g t h a r e p l o t t e d i n F i g . 1 0

a n d a r e s e e n t o i n c r e a s e l i n e a r l y w i t h

i n c r e a s i n g m a n g a n e s e .

F or t h e a s - w e l d e d c o n d i t i o n , t h e

r e su l t s ( i n

N / m m

2

)

a r e d e s c r i b e d as

f o l l o w s w h e r e Y S is y i e l d s t r e n g t h a n d

U T S is u l t i m a t e t e n s i l e s t r e n g t h :

YS =3 1 4 + 1 0 8 M n ( 1 )

U T S = 3 9 4 + 1 08 M n ( 2 ) .

F or t h e s t re s s - r e l i e v e d c o n d i t i o n , t h e

e q u i v a l e n t e q u a t i o n s w e r e c a l c u l a t e d

t o b e :

3

C .

• 5 0

- 8 0 - 6 0 - 4 0 - 2 0 0

T E S T T E M P E R A T U R E

2 0

Fig. 14—Schnadt impact test results

C

(as-welded)

Y S = 3 1 1 + 8 9 M n ( 3 )

U T S = 3 9 0 + 9 8 M n ( 4 ) .

F or t h e s p e c i f i c w e l d i n g c o n d i t i o n s

e m p l o y e d , it w a s f o u n d t h a t a n

i n c r e a s e o f 0 . 1 % m a n g a n e s e i n t h e

d e p o s i t in c r e a s e d t h e t e n s i l e p a r a m e

t er s b y a p p r o x i m a t e l y 1 0 N / m m - .

S t re s s r e l i e v i n g o f t h e s y s t e m ( C - M n )

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

d e c r e a s e , t h e d r o p b e i n g d e p e n d e n t

o n t h e m a n g a n e s e l e v e l .

Toughness Results. T h e C h a r p y V

t r a n s i t i o n c u r v e s f o r a s - w e l d e d d e p o s

i t s a r e g i ve n i n F i g . 1 1 . T h e C O D t e s t

r e s u l ts o b t a i n e d f o r s a w n o t c h e d s p e c

i m e n s a r e p l o t t e d i n F ig . 1 2 a n d t h e

Sc h n a d t te s t r e su l t s a r e g i v e n i n F i g s .

1 3 a n d 1 4 f o r t h e K„ a n d B„ c o n d i t i o n s ,

r e s p e c t i v e l y .

T h e d a t a a r e r e p l o t t e d c o n s e c u t i v e l y

i n F i g s. 1 5 t o 1 8 , a s a f u n c t i o n o f w e l d

m e t a l m a n g a n e s e a n d i t is s e e n t h a t

t h e f o u r d i f f e r e n t t es t p r o c e d u r e s

e x h i b i t e d t h e s a m e g e n e r a l t r e n d s .

I n c r e a s in g m a n g a n e s e l o w e r e d t h e

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

t i o n c u r v e s t o l o w e r t e m p e r a t u r e s u n t i l

a n o p t i m u m c o n d i t i o n h a d b e e n

a t t a i n e d at a m a n g a n e s e c o n t e n t o f

a p p r o x i m a t e l y 1 . 5 % . T h e r e a f t e r , i n

c r e a s in g m a n g a n e s e b e c a m e d e l e t e r i -

7 2 - s l M A R C H 1 9 8 0



2 5 0

2 0 0

^ 1 5 0 -

O

c

U J

5

1 0 0

a

U J

DQ

C C

o

W 5 0

<

Cha r py -V

0-5 1 0 1-5 2 0

M A N G A N E S E IN W E L D , % .

Fig.

15—Effect

of manganese (Charpy V-notch)

0-5

1 0 1-5

M A N G A N E S E I N W E L D

%

Fig. 17—Effect of manganese (Schnadt K„)

ous, except at very low temperatures

where the lower shel f was ra ised.

The Charpy V-no tch impac t cu rves

for s t ress- re l ieved deposi ts are p lot ted

in Fig. 19 and th e data are recons idered

in Fig. 20, as a fun ct i on of manga nese.

Co m p a r i s o n w i t h t h e a s - we ld e d c o n

di t io n (F ig. 11) ind ica tes on ly a s l ight

d isp lacement , t he hea t t r ea tment hav

ing had a ben ef ic ia l e f fect at low

m a n

ganese and a de t r im en ta l e f fect at h igh

manganese contents . The extent of the

tempera tu re d isp lacement , a t t he 100

J

leve l ,

is given in Table 6.

The Charpy V curves obta ined on

test ing s t ra in aged impact specimens

are sho wn in Fig. 21 and the equ ivale nt

resul ts are p lot ted against manganese

3 0

2 0

E

a

1 0

0-5

1 0 T 5

MANGANE S E

IN

W E L D %

2 0

Fig. 16—Effect oi manganese (COD test, 20 x 26 mm, i.e.,

0.79

x

1.02

in.)

4 0 -

-

3 0 ( -

C D

or

LU

UJ 2 0

a

U J

CD

ce

O

CD

<

1

A

-

1

B

1

1

C

Schnadt

i

B o

1

D

•^-40°C

~~-50°

^^ -6 0°

~ ^- 70 °

.- 80 °

i

- 15

1 0

E

a

1 0 -

0 5 1 0 1-5 2 0


Fig. 18—Effect of manganese (Schnadt B„)

con ten t in F ig. 22. Ag ing d isp la ced the

curves to h igher temperatures, the

shif t at the 100

J

level being repor ted in

Table 7.

The la tera l sh i f t to h igher tempera

tures d i f fered accord ing to manganese

con ten t , a t t a in ing a ma x im um (C) and

then dec reas ing at the h ighes t co nce n

t rat ion inve st igate d. The overa l l e f fect

was f o r e lec t rode D to become the

best of the ser ies and for the opt imum

to be d isp laced re lat ive to that exhib

i ted for as-welded and st ress- re l ieved

deposi ts .

Di s c u s s i o n

The meta l lographic s tudies of the

four d i f f e ren t m angan ese-con ta in ing

deposi ts revealed marked d i f ferences

in microst ructure. In as-deposi ted

we ld m eta l , as exem pl i f ied by t he t op

cent ra l bead, increasing amounts of

manganese progress ive ly increased the

amount of ac icu lar fer r i te , a t the

expense o f p ro -e u tec to id f e r r i t e and o f

in te rmed ia te lame l la r component . Fur

t he rmore , t he ac icu la r f e r r i t e , per se,

became progress ive ly more ref ined

(Table 3) . The rehe ated region s w ere

W E L D I N G R E S E AR C H S U P P L E M E N T I 7 3- s



2 5 0

2 0 0

^1501-

O

LU

5

1 C

Q

UJ

CD

CC

O

en

5 0

CO

<

A -

B -

c -

D

-

I i i

C h a r p y - V

1

1 /

/

•/•-

/ /

f t

/ / /

/ , • ' /

/ / / /

/ , • /

/ / /

/

/ /

/

y

i

S T R E S S -

1 1 1

1

•RELIEVED

,

2 5 0

- 3 0

2 0

E

Q.

10

- 8 0 - 6 0 - 4 0 - 2 0 0 2 0

T E S T

T E M P E R A T U R E ,

°C.

Fig. 19—Charpy

V-notch

impact results (stress relieved)

C h a r p y - V

D

RELIEVED

3 0

2 0

E

1-

a

1 0

1 0 1 5 2 0


Fig.

20—Effect of manganese (Ch V, stress relieved)

s imi lar ly af fected, the coarse gra ined

and the f ine gra ined zones a lso

becoming increasingly f iner . The over

a l l in f luence o f manganese on m ic ro -

st ructure thus appeared to be benef i

c ia l t h roughou t , t he measured param

e te rs chang ing m ono ton ic a l l y .

The spec i f i c we ld ing cond i t ions em

plo yed w ere such as to indu ce th e

larger por t ion of the cent ra l par t o f the

ISO 2560 de pos its to recry stall ize . For

example , a t t he Charpy V-no tch loca

t i o n , i t was fo un d, on the average, that

only 20% of the s t ructure rema ined in

the co lumnar f o rm . The amount o f

recrysta l l iza t ion is cons idere d to be an

im p o r t a n t f a c t o r i n f l u e n c in g m e c h a n

ical propert ies

7 51

and must there fore be

borne in m ind when a t t empt ing t o

eva lua te t he in f luence o f a l loy ing e le

ments.

Tensi le tests resul ts conf i rm that

manganese increases the y ie ld

st rength and tens i le s t rength of i r o n -

manganese alloys.

11

For the range of

manganese con ten ts inves t iga ted ,

so l

i d so lu t ion harden ing and g ra in re f ine

ment led to a l inear in f luence, an

increase of 0.1% M n increasing the

tensi le parameters by 10 N/mm

2

The

lat ter va lue compares favorably , but

perhaps inadver ten t ly , t o t ha t quo ted

by Bra in and Smith

1

for mi ld s teel CO;,

weld meta l and by Tu l ian i

6

for sub

merged arc weld meta l .

The tens i le proper t ies decreased

af ter s tress re l iev ing , the d rop bein g

greater in the case of yield strength

and h igh manganese levels . Carb ide

prec ip i t a t ion occur red a t g ra in bound

ar ies dur ing the heat t reatment , but

ev iden t ly no secondary harden ing oc

cur red in t he p la in C-Mn we ld meta l

svstem over t he t ime invo lved .

Table 6 -

Electroc

A

B

C

D

Effect of St

Temp.

e A W

- 2 7

- 4 4

- 5 3

- 4 3

ress

Relief

°C at 100 |

SR

- 3 2

- 4 4

- 5 0

- 3 6

(at 100 J)

D i sp l a ce

ment ,

°C

- 5

0

+ 3

+ 7

' AW— as-weld ed; SR—stress-relieved.

°F = (9/5)°C + 32

The toughness da ta ob ta ined us ing

the Charpy V-no tch , Schnad t (K

(

, and

B„)

and COD test revealed the same

general t rend in all cases. Thus, it can

be conc luded tha t t he un ive rsa l Char

py V test can be conf ident ly appl ied

for rout ine c lass i f icat ion of e lect rodes

according to ISO 2560. In pract ical

app l ica t ions , however , when cons ider

ing proper t ies in the fu l l th ickness of

the jo int , the COD test is a requis i te

for evaluat ing f i tness for purpose and

de term in in g cr i t ica l defect s izes. A

poss ib le co r re la t ion ex is t ing be tween

Charpy V-no tch and COD perhaps

only appl ies when the extent of s t ra in

ag ing is low. Fur thermore , a re la t ion

sh ip cou ld poss ib ly be on ly expec ted

wh en the e lec t rodes com pared a re , as

in the present instance, of the same

slag-base type.

In

accord w i t h Nakayama et al. it

was found that increasing manganese

decreased the upper shel f o f the t r a n

s i t ion curves. The increasing y ie ld

st reng th resul ted in a greater ten den cy

to m ic rovo id coa lescence dur ing t he

duct i le mode of f racture. In cont rast ,

manganese had a bene f ic ia l in f luence

on the lower shel f due to the ef fect on

cleavage resistance.

9

In the t rans i t ion region of the

impact curves for as-welded deposi ts ,

manganese had an op t im um in f luenc e

at 1.5% manganese, despi te the pro

g ress ive improvement in m ic ros t ruc

t u re t h roughou t . The pa t t e rn o f behav

ior is t hus depe nden t on t he c om pet

ing act ions of the e lement to :

1. Increase the y ie ld s t rength.

2. Increase the ac icu lar fer r i te v o l

ume f ract ion and to ref ine the gra in

s ize in the reheated region.

St ress re l iev ing of the deposi ts had

v i r t ua l l y no in f luence on t he Charpy

V-n otc h test resul ts , and peak p roper

t ies we re a lso exh ib i te d at the 1.5% M n

leve l . Fur thermore, i t appears that the

decrease in toughness expe cted as a

resul t o f carb ide prec ip i ta t ion was

compensa ted f o r by an oppos ing

me cha nism , e.g., a sof te ning o f th e

ferr ite.

St ra in aging of the four exper imenta l

we ld meta ls induced a cons iderab le

degree o f embr i t t lement .

In

C - M n

depos i ts i t is general ly ac cepte d tha t

the major so lute causing the decrease

in resistance to cleavage fracture is

n i t r o g e n . W ith in th e range of scat ter ,

no t rend in n i t rogen content ex is ted

over the range of manganese contents

s t u d i e d ,

t he va lues be ing be tween 69

and 96 ppm. Manganese is repor ted

1

'

2

t o d im in ish t he ag ing t endency o f

steel,

and op in io n var ies as to w he the r

the e leme nt shou ld be jud ge d on i ts

o wn m e r i t s o r wh e t h e r t h e c o m b in e d

ef fect of manganese and carbon is of

greater s igni f icance. The re lat ive d is

p lacement on s t ra in aging (Table 7)

was inconsis tent and the reason

rema ins en igmat ic , o ther t han t ha t

g ra in re f inement a lone becomes the

con t ro l l ing f ac to r . The observed t rend

74-sl MA RC H 1980



i OU

2 0 0

—

1

^150

a

UJ

z

m

100

Q

UJ

CD

QC

O

v> 5 0

CO

<

0

I

A

B —

c — -

_ D

-

STRAIN

I

I

~

AGED

I

I I I I

Charpy -V

/

yS7

/ / / /

• / / /

i'

f

/

nil -

/ ii/

' y

i i i i

- 3 0

- 8 0 - 6 0 - 4 0 - 2 0 0 2 0

TEST TEMPE RATURE ,°C .

Fig. 21—Charpy

V-notch

impact results (strain aged)

- 2 0

E

f

j

- 1 0

2 5 0

2 0 0

C h a r p y - V

3 0

2 0

E

Q.

10

10 T5

MANGANESE IN WELD ,5

Fig. 22—Effect of manganese (Ch V, strain aged).

w a s s u c h t h a t d e p o s i t D e x h i b i t e d t h e

b e s t i m p a c t p r o p e r t i e s , t h e o p t i m u m

b e i n g d i s p l a c e d a w a y f r o m t h e p r e

v i o u s l e v e l o f 1.5 % M n .

T h e p r e s e n t w o r k is c o n s i d e r e d a s a n

i n i t i a l s t e p f o r t h e u l t i m a t e u n d e r

s t a n d i n g o f t h e r o l e o f m i c r o s t r u c t u r e

i n m u l t i - r u n m a n u a l m e t a l a r c d e p o s

i ts .

E v e n t u a l l y , it is i n t e n d e d t o a d d

a l l o y i n g e l e m e n t s , e . g ., M o , N i a n d C r ,

t o t h e f o u r d i f f e r e n t m a n g a n e s e l e v e ls

a n d e v a l u a t e t h e c h a n g e s i n s t r u c t u r e

a n d p r o p e r t i e s . F i r s tl y , h o w e v e r , it is

f e l t t h a t f u r t h e r w o r k s h o u l d b e c o n

d u c t e d o n t h e C - M n s y s t e m s o a s t o

a p p r e c i a t e t h e p a r t p l a y e d b y c a r b i d e

d i s t r i b u t i o n a n d m o r p h o l o g y . T o f a c i l i

t a t e t h i s , i t is i n t e n d e d t o s t u d y t h e

f o u r w e l d m e n t s in t h e n o r m a l i z e d a n d

n o r m a l i z e d - a n d - t e m p e r e d c o n d i t i o n s .

C o n c l u s i o n s

F o r I S O 2 5 6 0 w e l d m e n t s d e p o s i t e d

a t 1 k j / m m w i t h b a s i c e l e c t r o d e s o f a

s p e c i f ic s l a g -b a s e t y p e , t h e f o l l o w i n g

c o n c l u s i o n s a p p l i e d :

1.

I n c r e a s i n g m a n g a n e s e , i n t h e

r a n g e 0 . 6 t o 1 .8 % , i n c r e a se d t h e

a m o u n t o f a c i c u l a r f e r r i t e i n a s - d e p o s

i t e d w e l d m e t a l a n d d e c r e a s e d t h e

a m o u n t o f p r o - e u t e c t o i d f e r r i t e a n d

i n t e r m e d i a t e c o m p o n e n t .

2. I n c r e a s i n g m a n g a n e s e r e f i n e d t h e

a c i c u l a r f e r r i t e in t h e a s - d e p o s i t e d

w e l d m e t a l .

3 . I n c r e a s i n g m a n g a n e s e r e f i n e d t h e

c o a r s e g r a i n e d r e g i o n o f t h e h e a t -

a f f e c t e d w e l d m e t a l .

4.

I n c r e a s i n g m a n g a n e s e r e d u c e d

t h e g r a i n s iz e o f t h e e q u i a x e d f i n e

g r a i n e d z o n e o f t h e h e a t - a f f e c t e d

w e l d m e t a l .

T a b l e 7 - E f f e c t of Strain

Electrode

A

B

C

D

T e m p .

A W

- 2 7

- 4 4

- 5 3

- 4 3

Ag i n g

°C at 100 J

SR

+ 5

- 5

- 1 2

- 1 9

(a t 10 0 ))<*'

D i sp l a ce

ment

°C><

+ 32

+ 39

+ 41

+ 24

181

AW—as -welded; SR—stress-relieved.

°F = (9/5)°C + 32

5 . T h e y i e l d a n d t e n s i l e s t r e n g t h s o f

t h e d e p o s i t s i n c r e a s e d b y a p p r o x i

m a t e l y 1 0 N / m m

2

p e r 0 . 1 % i n c r e a s e o f

m a n g a n e s e .

6 . C h a r p y V - n o t c h , S c h n a d t

(K, ,

a n d

B

0

)

a n d C O D t e s t s g r a d e d t h e t e s t

w e l d s i n t h e s a m e r e l a t i v e o r d e r .

7 . T h e o p t i m u m i m p a c t p r o p e r t i e s

o f a s - w e l d e d a n d s t r e s s - r e l ie v e d d e

p o s i t s w e r e a t t a i n e d a t 1 .5 % M n , d u e

t o t h e c o m p e t i t i v e i n f l u e n c e o f y i e l d

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

8 . S t r a in a g i n g e m b r i t t l e d t h e d e

p o s i t s a n d c h a n g e d t h e r e l a t iv e o r d e r

s u c h t h a t o p t i m u m i m p a c t p r o p e r t i e s

w e r e a c h i e v e d at a h i g h e r m a n g a n e s e

c o n t e n t .

Ac/cnow/ec/gments

T h e a u t h o r w i s h e s t o e x p r e s s h i s

t h a n k s t o t h e st a ff o f t h e W e l d i n g

I n s t i t u t e fo r c o n d u c t i n g p a r t o f t h e

m e t a l l o g r a p h i c w o r k u n d e r c o n t r a c t .

I n p a r t i c u l a r , t h a n k s a r e e x t e n d e d t o

D r . R. E . D o l b y f o r s u p e r v i s i n g t h e

s t u d i e s .

References

1.

Davey, T. G. , and

W i d g e r y ,

D. )., A

Techn ique fo r t he Charac te r i sa t i on o f We ld

M e t a l M i c r o s t r u c t u r e s ,

II W

Doc. I I -A-389-

76.

2.

D e t e r m i n a t i o n o f H yd r o g e n in W e l d

M e t a l , ISO 3690.

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