Surfacing of 3.25% Nickel steel with Inconel 625 by the gas metal arc welding-pulsed arc process

8/10/2019 Surfacing of 3.25% Nickel steel with Inconel 625 by the gas metal arc welding-pulsed arc process

1/8

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 , J A N U A R Y , 19 78

S p o n s o r e d b y t h e A me r i c a n We l d i n g S o c i e t y a n d t h e We l d i n g R e s e a r c h C o u n c i l

i f 1)1

Surfacing of 3.25% Nickel Steel with

Inconel 625 by the Gas Metal Arc

Weld ing-Pulsed Arc Process

Inconel

625

can be surfaced onto 3.25 nickel steel with

excellent weldability, equivalent mechanical properties

and good corrosion and fatigue resistance

BY D. F. HASSON, C. ZANIS, L. APRIGLIANO AND C. FRASER

ABSTRACT. The resul ts of a metal lur

g ica l charac te r iza t ion o f I ncone l 625

we ld meta l su r faced on to 3 .25% n icke l

s teel us ing the gas metal arc weld ing

process are presented. I t was found

tha t I ncone l 625 was d i rec t ly we lda b le

on to 3.25 n ick el s teel . Ten si le p rope r

t ies were genera l ly comparab le t o

those for 3.25 n ick el s tee l , and the

most f avorab le mechan ica l p roper t ies

were ob ta in ed w i th a hea t inp u t o f

1.77 MJ/m (45 k j / in . ) .

The cor ros ion fa t igue s t reng th o f t he

sur face weld metal at 10 cycles was

found to be 10.34 MPa (15 ks i) , which

is lower than values repor ted for

mu l t ip le pass Incone l 625 we lds bu t i s

s ign i f i can t ly h igher t han the cor ros ion

fat igue st rength of the steel . Fat igue

crack growth rates for the sur face weld

meta l were found to be h igher t han

t h e w r o u g h t

lnconel-625

base metal

and the steel .

The seawater cor ros ion res is tance of

t he sur face we ld meta l was equ iva len t

to the wrought base metal at levels of

i r on up to 9%, p rov ided the mo lyb

denum concent ra t ion was g rea te r t han

8%. St ress re l ie f heat t re atm en t d i d no t

degrade cor ros ion o r f a t igue p roper

ties.

I n t r o d u c t i o n

Many mar ine app l ica t ions requ i re

bo th h igh s t reng th and cor ros ion res is

t an t mater ia ls f o r long te rm re l iab i l i t y

and per fo rmance. O f ten the s t reng th

can

best

be achieved by the use of

steels which do not possess the

required res is tance to seawater cor ro

s ion damage. A possib le mater ia ls

s o lu t i o n t o p r o v id i n g s t r u c t u r a l c o m

p o n e n t s wh i c h c o m b in e t h e a t t r i b u t e s

o f h igh s t reng th and seawater cor ro

s ion is to we ld sur face th e steel w i t h a

m e t a l l u r g i c a l l y c o m p a t i b l e c o r r o s io n

res is tan t a l loy . Among the charac te r is

t ics desira ble in such a sur fa c ing a l loy

are reasonab le s t reng th , we lda b i l i t y t o

the steel , res is tance to general and

loca l ized cor ros ion a t t ack and good

cor ros ion fa t igue p roper t ies . A cand i

da te mater ia l f o r su r fac ing wh ich has

D. F. HASSON is Assistant Professor,

Mechanical Engineering Department,

United States Naval Academy, and

C

ZANIS, L. APRIGLIANO and

C FRASER

are

with the Materials Department of the David

W. Taylor Naval Ship

Research

and Devel

opment

Center

Annapolis, Maryland.

exce l len t co r ros ion res is tance ' and

we ld a b i l i t y

2

-

1

is lncone l -625* ( IN-625) .

There are, however , several factors

wh ich shou ld be inves t iga ted p r io r t o

using IN-625 to sur face steel . Since the

m a x im u m a l l o wa b le i r o n c o n c e n t r a

t ion is 5% for

IN-625

and higher levels

may be an t ic ipa ted due to p ick -up

f rom the steel base metal , the ef fect of

i r on con ten t on the seawater cor ro

s ion res is tance of IN-625 weld metal

mus t be de te rm ined . A lso , t he fa t igue

crack growth res is tance of the IN-625

weld metal appears sensi t ive to the

microst ructure (gra in s ize and shape).

5

Thus, the cor ros ion fat igue st rength of

t he sur faced IN-625 we ld meta l shou ld

be establ ished.

Th e c o m p o s i t i o n , m e c h a n i c a l p r o p

er t ies and cor ros ion res is tance of the

sur faced we ld meta l may be a l t e red by

we ldi ng heat inp ut . I t is , the refo re, of

in te res t t o de te rm ine the l im i t ing

c h e m ic a l c o m p o s i t i o n (e.g., i r on c o n

cent ra t ion) o f IN-625 sur face we ld

meta l on the basis o f m echa n ica l and

cor ros ion p roper t ies w i th a v iew to

*lnconel is a registered trademark of the

International Nickel Company.

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 1-s


2/8

Table1Chemical Analyses of IN-625

Filler Metal, Base Metal, and 3.25 Nickel

Steel,

wt-%

Table2-Welding Parameters for Surfacing of IN-625 on 3.25 Nickel Steel

N i

Cr

M o

Fe

Nb & Ta

Si

Al

Ti

C

M n

IN-625

f i l ler

meta l

60.66

22.18

9.14

3.42

3.69

0.24

0.22

0.29

0.04

0.01

IN-625

base

meta l

62.00

21.41

8.64

2.73

4.15

0.30

0.24

0.27

0.03

0.15

3.25

n icke l

s teel

3.27

0.40

0.43

Bal.

0.22

-

-

0.26

0.35

using IN-625 for sur fac ing of a mar ine

steel,

such as 3.25 nickel steel.

The approach for the present s tudy

was to vary the heat input on a par t ic

u la r we ld p rocess and eva lua te t he

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

mechan ica l p roper t ies . The hea t inpu t

wh ich gave mechan ica l p roper t ies

comparab le o r super io r t o t he 3 .25

nickel s teel was selected for the cor ro

s ion and fat igue tests.

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

Materials

The sur fac ing mater ia l was MIL-E-

21562 1.1 mm (0.045 in. ) d iameter IN-

625 f i l ler metal . The IN-625 was

sur faced onto 50.8 mm (2 in. ) th ick by

203.2 mm (8 in. ) wide by 609.6 mm (24

in.) long plates of 3.25 nickel steel.

A 25.4 mm (1 in. ) th ick hot ro l le d

and annea led p la te o f IN-625 wh ich

confo rmed to ASTM B-443

7

was used

to establ ish base metal proper t ies. The

chemical analyses of these mater ia ls

are g iven in Table 1.

Voltage

peak/

background,

V

33 34/26

33 34/26

35 38/25 28

36 38/26 28

Current,

A

200-220

200-220

190-210

180-205

Travel

speed,

mm/sec

(ipm)

6.8 (16.0)

4.7 (11.0)

3.6 (8.5)

3.0 (7.0)

Deposit ion

rate,

kg/h

(Ib/h)

22 (10)

22 (10)

24 (11)

24 (I

I)

Heat

input,

MJ/m

(kj/ in.)

0.90 23)

1.34 34)

1.77 45)

2.08 53)

Weldment Preparation

One and two layers of IN-625 were

weld sur faced onto the steel p lates in

the f la t posi t ion by the gas metal arc

we ld in g - p u l s e d a rc ( G M AW - P) p r o

cess. The hea t inpu ts and w e ld ing

parameters are presented in Table 2.

Since the 3.25% nickel s teel may

requ ire a po stw eld st ress re l ie f hea t

t rea tment , a l l su r faced p la tes were

stress relief heat t reated at 649 C (1200

F) for 4 hours (h).

Evaluation

Weldab i l i t y was es tab l ished by

means of dupl icate, 180 deg 2T s ide

bend tes t s a t room tempera tu re . Bend

tes t spec imens con fo rmed to

M I L -

STD-00481C

and were cu t norma l t o

t h e we ld in g d i r e c t i o n , a s s h o w n i n F ig .

1. The one layer sur faced spec imens

included at least 3.2 mm (0.125 in.) of

we ld meta l . Tw o layer spec imen s had

at least 6.4 m m (0.250 in.) of w e ld

metal .

A f te r ben d ing , conve x sur faces were

v isua l ly examined fo r ev idence o f

c rack ing . I n add i t ion , sec t ions f rom a l l

we ld m e n t s we r e e x a m in e d m e t a l l o -

g raph ica l ly a f t e r e lec t rochemica l e t c h

ing in a so lut io n of 12 ml H

3

PO.,, 47 ml

H,SO, and 41 ml HNO., . The chemical

compos i t ions o f a l l we ld meta ls were

dete rm ined by X- ray f luo rescence

analysis.

A l l -we ld meta l t ens i le spec imens

were removed f rom each w e l d , as

show n in F ig. 1 , and co n fo rm ed to

ASTM spec i f i ca t ion

E8

for subsize f la t

t ens i le spec imens . Spec imens were

tested at room temperature at a s t ra in

r at e o f 0 .0 03 m m /m m /m in u t e . Fo u r

Rockwell-C

hardness measurements

were a lso per fo rmed on each w e l d

ment and the values were averaged.

Up o n c o m p le t i o n o f t h e a b o v e

we ld a b i l i t y , c h e m ic a l c o m p o s i t i o n a n d

tens i le p roper t y measurements , w e l d

ments were p repared a t a se lec ted

heat inpu t f o r eva lua t ion o f seawater

c o r r o s io n a n d c o r r o s io n - f a t i g u e p r o p

er t ies of the sur faced IN-625 weld

meta l .

As i l lust rated in Fig. 1, a l l co r ro

s ion pane ls and fa t igue spec imens

we r e r e m o v e d c o m p le t e l y f r o m we ld

meta l . For com par iso n in t he c or ros ion

tes ts , wr ou gh t IN-625 base meta l spec

imens were a lso eva lua ted . The sea

water cor ros ion tes t ing may be sum

mar ized as fo l lows :

1.

General Corrosion.

T w o w e l d

metal panels and two IN-625 base

metal panels each 203.2 X 76.2 x 2.5

S T R E S S - C O R R O S I O N

SPECIMEN

I NCO NE L 625

W E L D C L A D D I N G

T E NS I LE S P E CI M E N

C O R R O S I O N - F A T I G U E

G E N E R A L A N D

C R E V I C E - C O R R O S I O N

S P E CI M E N

3 . 25 N I C K E L S T E E L

SIDE-BEND

W E L D A B I L I T Y S P E C IM E N

Fig.1Orientation of specimens removed from Inconel 625surface welds

2 -s I J A N U A R Y 1 9 7 8


3/8

4 . 7 MM ( 3 / 16 ) D I A . SUPPORT R OD

_TEST P A N E L W I T H

12 . 7 MM (1/2 )

C E N T E R H O L E

22 MM

(7/8 i

D E L R I N W A S H E R

E X T E R N A L L Y T H R E A D E D 1 2 .7 M M

( 1 / 2 ) O . D . D E L R I N S L E E V E

Fig.2Multiplecre

vice corrosion test

assembly: A (left)

multiple crevice

test assembly; B

(right) grooved

Delrin washer

12.7 RADIUS

NOTE:

ALL DIMENSIONS IN

MM

THICKNESS

=

2.54

mm

Fig.

4Single-edge

notch crack growth rate specimen

Table3-Chemical Analyses of IN-625 Surface Weld Metal Surfaced onto 3.25 Nickel Steel

by the GMAW-P Process

Heat

i npu t ,

MJ/m

( k j / i n . )

0.90 (23)

1.34 (34)

1.77 (45)

2.08 (53)

0.90 (23)

1.34 (34)

1.77 (45)

2.08 (53)

I N -625 we l d

m

spec i f i ca t ion

N o .

o f

layers

1

1

1

1

2

2

2

2

etal

N i

58.74

56.78

55.30

60.57

61.72

60.97

60.77

62.53

Bal.

corr

Cr

20.97

20.60

20.17

21.25

21.32

21.10

21.52

21.50

20/23

Chem i c a l

p o s i t i o n ,

w t

M o

8.90

8.87

8.32

9.04

9.07

9.11

9.14

9.12

8 / 10

o

Fe

8.46

9.76

10.85

6.14

5.12

4.64

4.00

3.67

5.00

Max

C b

3.62

3.40

3.20

3.71

3.56

3.58

3.75

3.77

3.15/

4.15

A s -depos i t ed

th ickness ,

mm ( in . )

4.0 (5/32)

4.4 (11/64)

4.0 (5/32)

4.8 (3/16)

7.1 (9/32)

8.0 (5/16)

8.3 (21/64)

8.3 (21/64)

Fig. 3Bent-beam-type

specimen. (X0.165)

stress-corrosion

mm (8 x 3 x 0.1 in. ) were exposed for

s ix months in f lowing (0.6 m/s)

seawater.

2. Crevice Corrosion. Du p l ica te t est

panels of the weld metal and base

meta l were eva lua ted fo r c rev ice

cor ros ion res is tance us ing the mu l t ip le

c rev ice t ype con f igur a t ion s how n in

Fig. 2. Aga in tests we re pe r for me d in

f lowing seawater f o r s ix months .

3. Stress Corrosion. Du p l i c a t e b e n t -

beam type specimens, 304.8 x 76.2 X

3.2 mm (12 x 3 X 0.125 in.) were used

for s t ress-cor ros ion evaluat ion of the

sur faced we ld meta l .

Figure 3 shows the apparatus in

wh ich spec imens were loaded to a

surface stress of 379 MPa (55 ksi).

Spec imens were exposed in f lowing

seawater f o r 8 months a f t e r wh ich they

were examined for cracks or other

corrosion

damage.

4. Corrosion-Fatigue.

Fat igue char

ac te r iza t ion was per fo rmed us ing bo th

Krouse- t ype p la te spec imens to es tab

l ish an S-N curve and s ingle-edge

no tch ed (SEN) specim ens (Fig. 4) for

fa t igue c rack g rowth ra te measure

ments . Krouse- t ype spec imens were

tested in seawater at a cyc l ic f re qu en

cy of 23.3 Hz and a stress rat io R = 1

These spec imens were tes ted un t i l

f racture or unt i l the number of cyc les

exceeded

IO .

8

The SEN specimens were used to

measure the ef fect of pro longed st ress

relief t ime at 649 C (1200 F) on crack

gro wth ra te . The c rack g row th d i rec

t ion was para l le l t o t he co lumnar

dendr i t es o f t he we ld meta l . G rowth

ra tes were de te rm ined by measur ing

crack exten sion , Aa, oc cu rr in g af ter a

spec i fi c n um ber o f cyc les , AN . A l l SEN

specimens were tested in a 3.5% N a C I /

Fi.O

so lu t ion un t i l f r ac tu re .

Results and Discu ss ion

Composit ion and Microstructure

The che mic al analyses of the IN-625

sur face we ld meta ls p roduced a t f our

heat input levels for one and two layer

sur faces are g iven in Table 3. The

s p e c i f i e d l im i t i n g c h e m ic a l c o m p o s i

t ion f o r IN-625 we ld

m e t a l

is also

listed in Table 3.

T h e c h r o m i u m , m o l y b d e n u m a n d

c o lu m b iu m c o n c e n t r a t i o n i n t h e s in

g le and doub le layer sur face we ld

meta l were w i th in t he IN-625 we ld

metal speci f icat ions for a l l heat inputs.

Th e m a x im u m i r o n c o n c e n t r a t i o n o f

5%, how eve r , was exce eded in a l l

s ingle layer sur face weld metal wi th a

W E L D I N G R E S E A R C H

SUPPLEMENT I

3-s


4/8

2nd LAYER IN-625

5 Id LAYER IN-6 25

i n LAYER IN-625

INCREASING IRON

CO NTE NT,

RELATIVE

INCREASING IRON

CONTENT,

RELATIVE

Fig.5Microprobe traces across two-layer C M A W IN-625surface

weld showing relative iron levels: A (left)scan across both

interfaces of steel surface welds;

B (right)~closeup

scan of

steel/

Inconel 625 interface

0 . 9 0 M J / m

2 3

k j / i n

1 . 3 4 MJ/m

3 4 k j / i n

1 . 7 7 MJ/m

4 5

k j / i n

2 .08 M J /m

5 3

k j / i n

^HfP^imt

F/g. 6Structureoi C M A W Inconel 625

surface weld (heatinput-1.77 Ml/m (45 kll

in.)): A (top)transverse to welding direc

tion; B

(bottom)normal

to A. X250

(reduced

50

on reproduction)

high value of 10.85% for the 1.77 kj /m

(45 kj / in . ) heat inpu t .

I t was noted that sur face welds

prepared wi th a heat input o f 2 .08

k j /

m (53

k|/in.

had the lowest i ron

content in both sing le and two layer

deposi ts. Th is fact is a t t r ibuted to the

low amperage used at th is heat input ,

and par t icu lar ly to the slow weld t rave l

speed used to generate th is heat input

(Table 2). The slow travel speed results

in the weld ing arc be ing more

comp le te l y i n con tac t w i th the mo l ten

weld puddle than was the case at

h igher speeds and lower heat inputs.

At h igher w eld t rave l speeds, the arc

contacts more base meta l and h igher

leve ls o f i ron are p icked up in the

in i t ia l layer o f weld deposi t . The i ron

content o f the second layer o f sur face

weld appears to ver i fy that the amount

o f d i l u t i on decreased as the we ld in g

travel speed was decreased and as heat

input was increased.

Examina t ion o f the above chemica l

co mp o s i t i o n , a n d a s - d e p o s i t e d

thickness data in Table 3 indicates that

ViYJ

2 INCHES 3

4 5

ihlilililihhhlrtrtiWl

f f f / d i l i l i l i i i l

Fig.7Bend test specimens from C M A W (pulsed-arc) single layer Inconel 625 overlays

two- layer IN-625 welds can be sur

faced wi th a f ina l th ickness greater

than 6.4 mm

(V A

i n. ) and w i t h a che m

ica l composi t ion in the second sur face

laye r wh ich con fo rms to IN-625 .

Elect ron microprobe scans for i ron

were pe r fo rmed on samp les wh ich

included the stee l base meta l and two

layers o f sur face weld meta l . The

results of these scans are presented in

Fig.

5. I t is obs erv ed tha t the lev el of

i ron con tent is cons tant for a l l prac

t ica l purposes through the th ickness of

the f i rst layer o f the weld meta l .

How ever, there is a very na rrow zon e

at the weld meta l -stee l in ter face in

wh ich a d ist inc t grad ient in i ron

con ten t was obse rved . The appearance

of th is narrow zone is i l lust ra ted in

Fig.

5B.

As shown in F ig . 5 , the t ransi t ion

f rom the in i t ia l layer o f weld meta l to

the second layer is marked by an

abrup t reduct ion i n i ron con ten t .

Ag a in ,

the i ron leve l is constant

through the th ickness of the second

layer o f weld meta l . I t should be noted

that s imi lar t raverses on d i f ferent

samp les f rom the same we ldmen t

revealed ident ica l t rends. There were

di f ferences in the leve l o f i ron content

be tween beads in the we ld me ta l , bu t

the i ron con ten t was constan t th rough

the th ickness of each

bead.

Typ ica l micros t ruc tu res o f the IN-

625 sur face weld meta l prepared by

the GMAW-P process are presented in

Fig. 6 . The mic ros t ruc ture t ransverse to

the we ld ing d i rec t i on cons is ts o f

co lumnar dendr i tes wh ich g row no r

mal to the weld meta l /base meta l

in ter face wi th second phase par t ic les

concen t ra ted in the i n te rde ndr i t i c

regions. I t was noted that the

co lumnar dendr i tes were , i n some

cases, con t inuo us th roug h the i n te r

face of layers 1 and 2 of the surface

we ld me ta l . Thus, there appears to be a

h igh degree of gra in d i rect iona l i ty in

the sur face microst ructure.

Figure 6B i l lustrates the surfacing

deposi t microst ructure t ransverse to

the co lumnar dendr i t i c s t ruc tu re d i s

cussed above and shows a f ine, ra ther

un i form d ispersion of severa l phase

part ic les in the weld meta l st ructure.

These part icles may be carbides r ich in

n icke l ,

c o l u m b i u m , o r m o l y b d e n u m ,

as sugges ted in the l i t era tur e. '

Examina t ion o f micros t ruc tu res

f rom the GMAW-P su r faced we ld

meta ls revealed that the dendr i te arm

spacing genera l ly increased wi th in

creasing heat input. This resulted in a

re la t ive ly coarse microst ructure in the

weld deposi ts fabr icated at the h ighest

heat input . I t should be noted that

me ta l l og raphy o f the we ld depos i t s

and of the HAZ of the base meta l d id

not show any evidence of cracking.

Weldability Testing

Al l s ide bend test specimens f rom

4 - s I JA N U A R Y 1 9 7 8


5/8

Table4 Tensile and Hardi

Heat input ,

MJ/m (kj/in.)

0.90 (23)

1.34 (34)

1.77 (45)

2.08 (53)

0.90 (23)

1.34 (34)

1.77 (45)

2.08 (53)

0.90 (23)

3.25 Nickel Steel

less

Properties

Layers

1

1

1

1

2

2

2

2

3

of IN-625 C M A W Pulsed Arc )

U l t i m a t e

tens i le s t rength ,

MPa (ks i )

801 (116.2)

787 (114.1)

77 6

(112.6)

790 (114.6)

810

(117,5)

839 (121.7)

818 (118.6)

834 (120.9)

793 (115.0)

772 (112.0)

751 (108.9)

806 (116.9)

869 (126.0)

814 (118.0)

849 (123.2)

873 (126.6)

775 (112.4)

785 (113.8)

80

min

Surface Weld Meta l on

0.2%

y ie ld s t rength ,

MPa (ks i )

461 (66.9)

462 (67.0)

443 (64.2)

461 (66.9)

512 (74.3)

516 (74.9)

498 (72.2)

525 (76.2)

517 (75.0)

532 (77.2)

515 (74.7)

568 (82.4)

553 (80.2)

535 (77.6)

550 (79.7)

561 (81.4)

539 (78.2)

536 (77.8)

55 min

3.25

Nickel Steel

Elongation

in 1 in. , %

31

28

29

28

33

28

28

28

18

21

25

31

34

23

31

36

18

14

22

min

Hardness ,

R,

17

16

22

22

18

21

20

24

16

t he GMAW sur fac ing depos i t s per

f o rmed sa t is fac to r i l y , and there was no

ev idence o f c rack ing in t he we ld meta l

or HA Z as a resul t of app l ica t ion of 180

deg ben d a ro und a 2T rad ius

m a n

dre l .

Typical s ide bend test specimens

f rom the GMAW sur face we ld meta ls

are pres ente d in Fig. 7. These results

a t t es t t o t he good we ldab i l i t y o f IN-

625 to s teel . Fur ther , i t should be noted

that a l l sur face welds were st ress- re l ie f

hea t tr ea ted p r io r t o t es t ing . The ab ove

resul ts indicated that the 649 C (1200

F)

for 4 h stress relief heat t reatment

d id no t adverse ly a f f ec t we ldab i l i t y .

Tensile Properties

The tensi le proper t ies of the IN-625

sur face we ld meta ls p repared by the

GMAW-P process a re p resen ted in

Ta b le 4, a l o n g w i t h t h e m i n im u m

required tensi le proper t ies for the 3.25

nickel s teel . For the s ingle- layer sur

face welds, a l l measured IN-625 tensi le

proper t ies exceeded the tens i le p rop

er t ies speci f ied for 3.25 n ickel s teel .

The bes t combina t ion o f s t reng th and

duc t i l i t y was measured on spec imens

f rom th e s ing le - layer surfaces p repare d

at heat inpu ts of 1.77 and 2.08 M | / m

(45 and 53 k j / in . ) .

The we ld meta l s treng th p rope r t ies

measured on spec imens removed f rom

tw o layer sur faces ( inc l ud ing layers 1

and 2 ) were genera l ly h igher t han the

values measured for s ingle layers,

par t icu la r ly w i t h respec t t o t he y ie ld

s t reng th . Once aga in , t he bes t combi

na t ion o f s t reng th and duc t i l i t y was

observed in welds fabr icated at 1.77

and 2.08 MJ/m (45 and 53 k j / in . ) . I t

was noted in the tensi le data for the

two- layer spec imen prepared a t a hea t

inpu t o f 0 .90 M J / m (23 k j / i n . ) t ha t t he

tens i le e longat ion va lues d id no t meet

the m in imum requ i rement f o r 3 .25

nickel steel of 22%.

Examinat ion of the f racture sur faces

o f t hese spec imens revea led a number

o f lack o f f us ion de fec t s wh ich caused

premature tens i le f rac tu re . Th is obser

vat ion suggests that the 0.90 MJ/m (23

kj / in . ) heat input is not suf f ic ien t to

ob ta in t he requ i red degree o f f us ion

with the in i t ia l layer of IN-625. There

was some sca t te r be tween the u l t i

mate tens i le s t reng th and e longat ion

va lues measured on dup l ica te spec

imens f rom the 1.34 and 1.77 MJ/m (34

Fig.

8Typical

tensile fracture surface of

Inconel 625 surface we ld metal on 3.25

nickel steel by the GM AW (pulsed arc)

process. A (top)-

X

225;

6 (bottom)-

X2000

and 45 k j / in . ) su r face we lds .

The var ia t ion on dup l ica te spec

imens was p robab ly due to observed

sca t te red in te rd end r i t i c m ic ro poro s i t y

in t he spec imens . As shown in t he

f ractographs of Figure 8, tensi le f rac

tures of the specimens f rom the

G M A W o v e rl a ys we r e d u c t i l e i n n a t u r e

and occur red a long the dendr i t e in te r

faces.

Examinat ion of the hardness data in

Table 4 reveals that there was a good

cor re la t ion be tween the tens i le

st rength of the over lay and the Rock

wel l C hardness. I t appears that a

m in imum average hardness o f Rock

wel l C16 is indicat ive of a tensi le

st rength greater than

758

MPa (110 ksi)

in t he IN-625 sur face we ld meta l .

Corrosion-Fatigue

The resu l t s o f h igh-cyc le cor ros ion

fat igue tests on IN-625 we ld me tal

sur faced by the GMAW-P process a t a

heat inp ut of 1.77 M | / m (45 k j / in . ) are

presen ted in Fig. 9, wh ere the S-N

curves for IN-625 mult ip le pass

w e l d

ments and for 3.25 n ickel s teel tested

in seawater are a lso inc luded for

c o m p a r i s o n .

1

The test resul ts on IN -

625 sur face we ld meta l exh ib i t e d so me

scat ter , but general ly l ie below the

mul t ipass IN-625 we ld curve and

above the steel curve. The fat igue

st rength of the IN-625 sur face weld

me tal in seaw ater is 103 MP a (15 ksi).

The lower f a t igue s t reng th o f t he

sur faced IN-625 weld metal may be

due in par t t o t he d i rec t iona l i t y in t he

mic ros t ruc tu res o f t he sur faced we ld

meta l wh ich was d iscussed above .

Work by

Long'

1

indica tes that the

rate of pro pa ga t ion of a fat ig ue crack

in the IN-625 sur face weld metal is

more rap id when the c rack is mov ing

W E L D I N G R E S EA R C H SUPPLEMENT I 5-s


6/8

-

1

1 ^v

3.25

NiSTEEL

V

SEAWATER (RCB

SPECIMENS)

( R E F E R E N C E 101

PRESENT

o - IN 625 G MAW

- IN-625 GMAW

C O N T A I N I N G

_ L

I NCONEL 625

M U L T I P L E

1

W E L D M E N T ,

PASS

SEAW ATER ( RCB

( R E F E R E N C E

S t \ o

I N V E S T I G A T I O N ^ s

C L A D

C L A D

W E L D M E T A L

W E L D M E T A L

1 / 4 W ELD FLAW S

0 /

I

SPECI MENS)

10)

~S~

I NCONEL

C L A D D I N G

1

625 W ELD

SEAW ATER

^-o

1

-

STRESS- I NTENSI TY FACTOR RANGE AK . MPA ArT

20 30 40 50 60 8 100

I I I I I I 25 000

CYCLES TO FA I LURE, N

Fig.

9High-cycle

fatigue curve for Inconel 625 surface weld m etal in seawater

para l le l t o t he dendr i t e ax is t han when

moving normal to i t . I t has a lready

been ment ioned tha t t he Krouse spec

imens were removed so tha t c rack

growth wou ld p roceed para l le l t o t he

axis o f t he long co lu mn ar de ndr i t es o f

the sur face w e l d . The mu l t ipass we ld

spec imens , on the o ther hand,

c o n

s is ted o f a much more randomly

or ien ted m ic ros t ruc tu re . The low er

fat igue proper t ies of the sur face weld

meta l compared to t he mu l t ip le pass

we lds , t here fo re , appear t o resu l t f r o m

t h e c o m b in e d e f f e c t o f

microdefects

n o r m a l l y e n c o u n t e r e d i n we ld m e t a l s

and an un favora b ly a l igned m ic ro -

st ructure.

Another f ac to r wh ich mus t be no ted

rega rding th e fa t igue resul ts in Fig. 9 is

tha t t he Krouse spec imens used here in

expose more weld metal sur face area

to test than the t ransverse weld

ro ta t ing can t i lever beam (RCB) spec

imens used to deve lop the mu l t ipass

we ldm en t curve . Thus , t he Krouse

test s a re cons id ered more conserva t ive

and shou ld be more represen ta t ive o f

t he fa t igue p roper t ies o f su r faced we ld

metal than the RCB data.

The e f f ec t s o f macroscop ic we ld

f laws , de tec tab le by bo th rad iogra ph ic

and penet ran t t es t ing , we re e xamine d

by tes t ing spec imens con ta in ing we ld

defects up to 6.4 mm (0.25 in.)

long ,

or ien ted bo th para l le l and norma l t o

the specimen axis, at stress levels of 41

MPa (6 ksi) and 103 MPa (15 ksi) in air

and seawa ter . As indi ca ted in Fig. 9,

these specimens surv ived 10

s

cyc les

wi th no de tec tab le inc rease in f law

size.

The ef fects of pro longed st ress re l ie f

hea t t r ea tment on fa t igue c rack in i t ia

t ion and p ropagat ion were a lso inves

t iga ted .

Ro t a t i n g c a n t i l e v e r - b e a m f a t i

gue spec imens were removed f rom IN-

625 base p la te t ha t had undergone a

simulated st ress- re l ie f heat t reatment

of 64 h at 649 C (1200 F), and were

tested at 276 MPa (40 ks i) an d 414 MPa

(60 ksi) in seawater. Test results were

comparab le t o h igh-cyc le f a t igue da ta

on annealed (982 C or 1800 F, 1 h,

A. C.) base metal tested in air

Fatigue-Crack Growth

Sing le edge no tch- t ype c rack p ropa

ga t ion spec imens cu t f r om sec t ions o f

a s ing le - layer sur face we ld w ere sub

jected to s t ress re l ie f heat t reatments

of 649 C (1200 F) for 4 and 64 h. These

spec imens were in tended to measure

the ef fect , i f any, of pro longed st ress-

re l ie f heat t reatment on fat igue crack

growth rates in the sur face weld

metal .

Resul ts of fat igue crack growth rate

tests on the IN-625 sur face weld metal

are presente d in Fig. 10. Also s ho wn in

Fig. 10 are resul ts of ea r l ier wo rk on

wrought IN-625 p la te and 3 .25 n icke l

steel.

5

It is no ted that the crack gr ow th

rates of the c lad weld metal are h igher

than ra tes f o r bo th t he wr ou gh t IN-625

and the 3.25 n ickel s teel .

The h igher g rowth ra tes in t he IN-

625 sur face we ld meta ls compared to

the wrought p la te a re a t t r ibu ted

pr imar i l y t o t he m ic ros t ruc tu ra l d i f f e r

ences be tween the two p roduc t f o rms .

The weld metals are character ized by

a n e lo n g a t e d d e n d r i t i c s t ru c t u r e w h i c h

was essent ia l ly paral le l to the crack

growth d i rec t ion . I n con t ras t , t he

wro ugh t mater ia ls a re charac te r ized by

an equ iaxed g ra in s t ruc tu re .

The e f f ec t s o f o r ien ta t ion and g ra in

s t ruc tu re on c rack g rowth ra te were

note d e lsewhere. ' Th e di f feren ces in

c rack g rowth ra tes be tween the sur

face weld metals heat t reated for 4 h

10 15 20 25 30 40 50 60 80 100

STRESS- I NTENSI TY FACTOR RANGE. AK . KS I / i N

Fig.

70

Crackgrowth rate, da/dN, vs. stress-

intensity range,

AK,

for IN-625 surface weld

metal

and 64 h at 649 C (1200 F) are not

cons idered s ign i f i can t . Fur ther , t he

relat ive posi t ion of the curves is in ter

preted to mean that pro longed st ress

rel ief heat t reatment does not a l ter

cor ros ion fat igue crack growth rates of

the c lad IN-625 sur face weld metal .

General Corrosion Tests

The chem ica l comp os i t io ns o f the

wrought IN-625 base meta l and o f t he

a l l -we ld meta l genera l co r ros ion tes t

panels are sh ow n in Tables 1 and 5,

respec t ive ly . The compos i t ion o f t he

wr o u g h t b a s e - a n d we ld - m e t a l s a m

p les co n fo rm ed to t he IN-625 base-

and we ld -m eta l spec i f i ca t ions . Fur

t her , t he com po s i t io n measured o n

both sur faces o f t he we ld -meta l pane ls

ind ica ted tha t t here was no s ign i f i can t

chemica l va r ia t ion th rough the spec

imen th ickness .

The genera l co r ros ion o f bo th t he

IN-625 base metal s tandards and the

sur face we ld m eta l , as de te rm ine d by

weight loss (Table 7), was v ir tual ly n i l

a f ter 6 months in seawater . Visual

examinat ion d id not reveal any s igns of

genera l co r ros ion .

As t h e c h e m ic a l c o m p o s i t i o n o f

these panels was s imi lar to the IN-625

6-s

I

JANUARY 1978


7/8

Table

5-Partial

Chemical Analysis of IN-625 Surface Weld Metal Seawater Corrosion Specimens

Composit ion, wt-%

Specimen type

General corro

sion

Side of surfacing analyzed

Free surface of weld

Side of weld closest to base metal

Cr

21.63

21.38

M o

9.37

8.53

Fe

4.42

4.64

C b

3.62

3.69

Crev ice cor ro- F ree sur face o f we ld

s ion S ide o f we ld c loses t t o base me ta l

St ress cor ros ion Free surface of w el d

I N -625 W e l d M e t a l S pec i f i c a t ion

20.70

20.61

20.95

20 / 23

9.28

9.34

9.28

8 / 10

8.60

9.44

5.80

5.00 Max

3.51

3.54

3.43

Cb and Ta

3.15/4.15

Table

6-Results

of General and Crevice Corrosion Tests on IN-625 Surface Weld Metal

and Base Metal

G ene ra l

c o r ros i on

Crev ice

c o r ros i on

S pec i m en

type

Sur face

w e l d

Base

meta l

Sur face

w e l d

Base

meta l

O r i g i na l

293.05

293.87

270.20

415.15

412.36

262.15

246.81

415.95

419.80

Wei gh t , g ram s

Final

293.02

293.80

270.18

415.12

412.32

261.62

246.68

415.92

419.80

Loss

0.03

0.07

0.02

0.03

0.04

0.53

0.13

0.03

0.00

mpy

Ni l

N i l

Ni l

N i l

N i l

0.2

Ni l

Ni l

0.0

Co r ros i on

rate

fiM/Year

Ni l

0.5

Ni l

Ni l

Ni l

3.9

1.0

Ni l

0.0

base plate, the resul ts indicate that the

s t ruc tu re o f t he sur face and we ld

metal and the st ress- re l ie f heat t reat

ment d id no t have a de t r im enta l e f f ec t

on the exce l len t genera l co r ros ion

resis tance inherent to the IN-625 base

meta l compos i t ion . The resu l t s o f

cor ros ion tes t s on pane ls w i th h igher

i ron contents are d iscussed in the

f o l l o w in g s e c t i o n s .

Crevice Corrosion.

The i ron and

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

c o r r o s io n p a n e l s we r e b o t h a p p r o x i

mate ly 9% (Tab le 5 ) . V isua l examina

t ion of two test panels revealed that ,

ou t of 40 po ten t ia l p i t s i tes, not on e p i t

wa s p r o d u c e d .

This resul t i l lust rates the excel lent

crev ice-cor ros ion res is tance of the sur

f ace we ld m eta l . The w e ig h t loss o f t he

sur face we ld -meta l samples was neg l i

g ib le ,

as indicated in Table 6. The

crevice-cor ros ion res is tance of these

s u r fa c e we ld - m e t a l p a n e l s wa s e q u i v a

lent to the base metal panels which

had no p i t s and neg l ig ib le we igh t loss .

Th is was expec ted s ince the mo lyb

d e n u m c o n t e n t , wh i c h c o n t r o l s c r e

v ice-cor ros ion res is tance , was ma in

ta ined above 8% , even w i t h a 9% i ron

c o n t e n t .

The c rev ice-cor ros ion tes t a lso p ro

v ides an indicat ion of the res is tance of

the sur face weld metal to general

cor ros ion at the 9% Fe level . Since the

c rev ice-cor ros ion tes t pane ls showed

no s igns of crev ice at tack or general

cor ros ion and s ince the weight loss

f rom these pane ls was neg l ig ib le , t he

general cor ros ion res is tance of sur face

we ld metal at the 9% Fe and 8% M o

leve ls shou ld be exce l len t .

Stress-Corrosion Cracking. Af ter 8

months of exposure to seawater at 90%

of y ie ld s t reng th , t he ben t -b ea m spec

imens o f

clad-weld

meta l d id no t

show s igns o f c rack ing o r cor ros ion .

These specimens had an i ron level of

5.8% and were stress relieved at 649 C

(1200 F) for 4 and 64 h. Thus, we ld c lad

IN-625 with th is i ron level and st ress-

re l ie f cond i t ion does no t have an

apparent s t ress-cor ros ion cracking

p r o b le m .

A p p l i c a t i o n C o n s i d e r a t i o n s

A l t h o u g h t h e r es u lt s o f w e ld a b i l i t y ,

mechan ica l p roper t y and seawater

cor ros ion tes t s repor ted here in i n d i

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

sur faced ' IN-625 we ld meta l a nd the

s tee l ,

t here a re cer ta in po in t s w h i ch

must be assessed pr ior to sur fac ing:

1. IN-625 is more noble than 3.25

n icke l s tee l , and the sur faced we ld

meta l shou ld represen t an impenet ra

ble bar r ier to prevent local ruptures in

the IN-625 and undes i rab le ga lvan ic

cor ros ion . I nspec t ion requ i rements

shou ld ensure tha t a l l accep tab le f laws

are ben ign and wi l l no t p ropagate .

2. The ap p l ica t io n o f aus ten i t i c

sta in less steel hardfac ing has been

repor ted to resu l t in un favorab le

tensi le res idual s t resses in the weld

deposi t , even af ter thermal s t ress

relief.

12

The re ten t ion o f t ens i le res id

ua ls in t he we ld meta l were a t t r ibu ted

to d i f ferences in the coef f ic ient of

t herma l expans ion be tween the s tee l

and the sur faced we ld meta l . Thus ,

coo l ing f rom the s t ress re l ie f t empera

ture can restore tensi le res iduals in the

sur faced we ld meta l wh ich may be

d e t r im e n t a l t o f a t i g u e p e r f o r m a n c e .

Sho uld such a s i tu at ion ar ise in the I N -

625/3 .25 n icke l s tee l sys tem, cons ider

a t ion o f co ld ro l l ing o r peen ing o f t he

sur face s tee l t o m in im ize o r e l im ina te

the tensi le res idual s t resses may be

necessary.

13

C o n c l u s i o n s

1. IN-625 is sat is fac tor i ly w eld ab le

to 3.25 n icke l s tee l us ing the G M A W -P

process. Stress relief heat t reatment at

649 C (1200 F) d id not adversely af fect

we ld a b i l i t y .

2. The tensi le prop er t ies of IN-625

sur face we ld meta l a re genera l ly com

parab le w i th t he requ i rements o f 3 .25

n icke l s tee l . The mos t f avora b le m e

chan ica l p roper t ies were ob ta ined

w it h a heat inpu t of 1.77 M J/ m (45

k j / in . ) .

3. The seawa ter cor ro s io n res is tance

of IN-625 sur face weld metal is equiv

a lent to that of wrought base metal at

i r on con ten ts o f up to 9%, p rov ided the

mo lybd en um c on te n t i s g rea te r t han

8%. For weld metals in the above

c o m p o s i t i o n l im i t s t h e c r e v i c e c o r r o

s ion res is tance was excel lent to good.

No suscept ib i l i t y to s t ress cor ros ion or

general cor ros ion was noted. St ress

relief heat t reatment at 649 C (1200 F)

for t imes up to 64 hours d id not a l ter

cor ros ion behav io r o f t he we ld meta l .

4.

t he seawater cor ros io n fa t igue

s t reng th o f c lad IN-625 we ld meta ls

was 103 MPa (15 ksi) at 10 cycles. This

va lue is lower t han IN-625 mu l t ip le

pass we ldm en ts , bu t i s s ign i f i can t ly

higher than that of 3.25 n ickel s teel .

5. The fat igue crack growth rate of

sur face IN-625 weld metal is h igher

than that of the wrought base metal

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

7-s


8/8

and 3.25 n ickel s teel when crack

gro wth p roc eeds in a d i re c t ion para l le l

t o t he h igh ly o r ien ted dendr i t i c s t ruc

tu re .

The inc reased c rack g rowth ra te

paral le l to the dendr i tes is bel ieved to

con t r ibu te t o t he lower f a t igue

s t reng th o f t he sur face we ld meta l

compared to mu l t ip le pass sur face

we ld m e n t s o r t h e w r o u g h t b a s e

plate.

References

1. Fink, F. W ., and Boy d, W . K., Th e

Corrosion of Metals in Marine Environ

me nts, AD 712 585,

NTIS,

Springfield, VA,

1970.

2. Gilliland, R.

C,

and Slaughter, G. M.,

The Welding of New Solut ion-Strength

ened Nickel-Base Alloys,

Welding lournal,

45 (7), July 1966, Research

Suppl.,

pp .

314-s

to 320-s.

3. Conaway, H. R.. and Mesick, |. H., A

Report on New Matrix-Stiffened Nickel-

Chromium Welding Products,

Welding

lournal,

49 (1), Jan. 1970, Research

Suppl.,

pp .27-s to 32-s.

4. Anon ., Incon el Alloy 625, Hun t ing-

ton Alloy Products Division, The Interna

t ional Nickel Company, Inc., Hunt ington,

WV, 1970.

5. Lo ng, T. A., Jr., Co mp aris on of F atigue

Crack Propagation in Inconel 625 and 3.25

Nicke l Steel, Masters Thesis, M.I.T., June

1972.

6. Electrod e and RodsW elding, Bare,

Nickel Alloy , Mi l Spec MIL-E-21562D, 25

May 1972.

7.

Nicke l -Chromium-Molybdenum-Co-

lumbium Alloy Plate, Sheet and Strip,

ASTM B433-66, 1974.

8. Mec han ical Tests for We lded Joints,

Military Standard, MIL-STD-00418C, 15 June

1972.

9. Tension Testing of Metallic Materials,

ASTM E-8, Phila., PA, 1974.

10. Czyryca, E., Un pub lished data,

DTNSRDC, Annapolis.

11. Kruger, J., and Am bros e, J. R., Th e

Role of Passive Film Growth Kinetics and

Properties in Stress Corrosion and Crevice

Corrosion Sus ceptibility, National Bureau

of Standards, IR76-1170, Nov. 1976.

12. Babaev, A. N., and Vainerman, A. E.,

The Residual Stresses in Hardfaced

Shafts,

Avt. Svarka,

No. 2, 1976, pp. 35-37.

13. Shoak, L.

L

Jr., and Long, C. L,

Surface Cold Rolling of Marine Propeller

Shafting, SNAME 1957, pp . 682-702.

WRC Bulletin 224

February 1977

Interpretive Report on Underwater Welding

by Chan-L iang Tsa i and Ko ich i Masubuch i

The fundamentals of underwater weld ing presented in th is repor t were based on the three-year research

program en t i t led

Fundamental Research on Underwater Welding

( conduc ted f rom Ju ly 1971 to June 1974

at

M.I.T.

for the Nat ional Sea Grant Of f ice). In th is repor t , techniques of improved underwater weld ing

processes recent ly conducted, both in th is count ry and abroad, are d iscussed. There are cur rent ly two

approac hes to the imp rov em en t of qua l i ty in unde rwate r welds. One is the develop men t of an im proved

(coa ted) e lec t rode to meet t he requ i rement f o r we ld ing underwater in wet cond i t ions . The o ther is t he

el iminat ion of the wet condi t ions around the arc zone v ia d irect shie ld ing.

Publ icat ion of the repor t was sponsored by the Interpretive'Reports Commi t tee o f t he Weld ing Research

Counci l .

The pr ice of WRC

Bulletin 224

is $8.50 per copy. Orders should be sent wi th payment to the Welding

Research Counci l . Uni ted Engineer ing Center . 345 East 47th St reet . New York. NY 10017.

WRC Bulletin 223

January 1977

Hot Wire Weld ing and Sur fac ing Techniques

by A. F. Manz

This WRC Bul le t in is d iv ided in to two par ts . The f i rs t par t prese nts a non -ma the ma t ical d escr ip t ion of the

Hot Wire processes and their general chara cter is t ic s. The second par t prese nts a genera l ized in-dep th

mathemat ica l t r ea tment o f e lec t rode me l t r a te phenomena. I n add i t ion to descr ib ing Hot Wi re e lec t rode

mel t ing , Par t I I a lso p resen ts cons iderab le in fo rmat ion concern ing the genera l case o f l-R heat ing of any

moving e lect rode. Examples are g iven to demonst rate the ut i l i t y of the der ived equat ions in predic t ing the

mel t ra tes, t emp era tu re d is t r ibu t ion a nd vo l t age d rops o f mov ing e lec t rodes . Speci fi c examples co ncern in g

Hot Wires are inc luded.

Publ icat ion of th is repor t was sponsored by the Interpret ive Repor ts Commit tee of the Welding Research

Counci l .

The pr ice of WRC

Bulletin 223

is $7 .50 per copy . Orders shou ld be sen t w i t h payment t o t he Weld ing

Research Counci l , Uni ted Engineer ing Center , 345 East 47th St reet , New York. NY 10017.

Surfacing of 3.25% Nickel steel with Inconel 625 by the gas metal arc welding-pulsed arc process

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Transcript of Surfacing of 3.25% Nickel steel with Inconel 625 by the gas metal arc welding-pulsed arc process