gta weldability studies on high

8/17/2019 GTA Weldability Studies on High

1/6

GTA Weldabi l i ty Studies on High

Manganese Stainless Steel

Progress is reported in isolating some of the factors

related to variabilities in we lding beha vior

BY W. S . B E N N E T T A N D G . S . M I L L S

A B S T R A C T . G T A w e l d a b i l i t y s t u d i e s

have been conducted on a re la t i ve ly

new aus ten i t i c s ta in less s tee l o f nom

i n al co m p o s i t i o n 2 1 C r - 6 N i - 9 M n - 0 . 3 N .

The a l loy i s cu r re n t l y m ad e by th ree

p r o ce sse s ; co n ve n t i o n a l a i r m e l t i n g ,

vacuum a rc reme l t ing (VAR) , and

electroslag r e f i n i n g ( E S R ) . E a ch

p r o ce ss p r o d u ce s m a t e r i a l o f so m e

wha t d i f fe ren t we ldab i l i t y .

Po ros i t y in a i rme l ted ma te r ia l i s

re la ted to ox ide inc lus ion leve l , and

n i t rogen con ten t wh i le VAR and ESR

poros i ty leve ls a re re la ted to n i t rogen

on ly.

S u r f a ce r o u gh n e ss a n d a r c s t a b i l

i ty a re s t rong ly in f luen ced by n i t ro

gen in a l l th ree types o f stee l . ESR

mate r ia l has p roduced much lowe r

dep th to w id th ra t ios (D /W ) than the

o the r two . The caus e of the poo r D /W

is appa ren t l y re la ted to the am oun t o f

a l u m i n u m p i cke d u p d u r i n g t h e r e -

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

a p p e a r s t o i n te r a c t w i t h m a n g a n e se

t o p r o d u ce i n c r e a se d m a n ga n e se i n

the arc.

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

High manganese s ta in less s tee l i s a

r e l a t i ve l y n ew a u s t e n i t i c s t a i n l e ss

stee l w i th a nomina l y ie ld st rength a t

room tem pera tu re in the annea led

cond i t ion o f 65 ,000 ps i (44 .8 MPa) .

The a l loy has exce l len t co r ros ion

res is tance , equa l to o r exceed ing tha t

The authors are associated with Dow

Chemical U.S.A., Rocky Flats Division,

Golden, Colorado.

Paper was selected as alternate for the

55th AWS Annual M eeting held at

Houston, T exas, during May

6-10

1974.

o f t ype 304 in most env i ronmen ts .

Fu r the r , the aus ten i te i s ex t reme ly

stab le making the a l loy very usefu l a t

c r yo ge n i c t e m p e r a t u r e s . T h i s d e s i r

a b l e co m b i n a t i o n o f p r o p e r t i e s h a s

resu l ted in increasing use o f the a l loy,

especia l ly in the a i rcra f t and nuclear

indus t r ies .

The chemistry l imi ts fo r the a l loy

a re shown in Tab le 1 . Cons ide rab le

so l id so lu t ion s t rengthen ing resu l ts

f rom the h igh n i t rogen con ten t . The

h i gh ch r o m i u m co n t e n t p r o d u ce s t h e

exce l len t co r ros ion res is tance and the

m a n ga n e se a n d n i t r o ge n p r o d u ce t h e

very stab le austen i te o f th is a l loy.

The a l loy i s p roduced by th ree dif

f e r e n t m e l t i n g p r a c t i c e s , c o n v e n

t iona l a i rme l t , vacuum a rc remelt

(VAR) , e lec t ros lag re f ined (ESR) .

E a ch m e l t i n g p r o ce ss p r o d u ce s m a t e

r ia l w i th som ewh a t d i f fe ren t im pu r i t y

chemis t r ies and d i f fe ren t inc lus ion

leve ls . These chem is t ry va r ia t ions

p l u s t h e h igh va p o r p r e ssu r e co m p o

nen ts o f the a l loy cou ld p roduce un

usua l and poss ib ly va r iab le we ld ing

behav io r .

Ea r l y expe r imen ts d id indeed show

qu i te a va r ia t ion in we ld in g behav io r

f rom one lo t o f mater ia l to another.

S o m e o f t h e co m p o n e n t s f a b r i ca t e d

f rom th is a l loy requ i re ex t reme ly p re

c i se a n d r e p r o d u c i b l e w e l d ge o m

e t r ies and low po ros i t y leve ls . The

var ia t ions seen f rom lo t to lo t fa r ex

ceeded the to le rances on some o f

these i tems. Because o f these p rob

lems a com pre hen s iv e s tudy o f the

GTA we ldab i l i t y o f th i s a l loy was un

d e r t a ke n . S e ve r a l a sp e c t s o f t h e

we ldab i l i t y have been found to be

somewha t un ique and a re repo r ted

here .

P o ro s i ty , S u r f a c e R o u g h n e s s

a n d A r c S t a b i l i t y

Ear ly a t temp ts to GTA we ld h igh

m a n ga n e se s t a i n l e ss s t e e l (HMSS)

p roduced we lds w i th la rge va r ia t ions

in po ros i t y , su r face roughness , and

a rc s tab i l i t y . Work has con t inued in an

ef fo r t to ident i fy bo th the cause and

the ex ten t o f these va r ia t ions .

Experimental P rocedures

GTA we lds have been made on a

num ber o f d i f fe ren t geom e t r ie s us ing

many d i f fe ren t cond i t i ons . Howeve r ,

f o r co m p a r i so n p u r p o se s , a u t o

ge n o u s w e l d s o n Vh in . (38 .1 mm ) or

2 in . (50 .8 mm ) d iam ba r s tock have

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

shown in Tab le 2 .

A f te r we ld ing , the cen te rs o f the

ba rs we re bo r ed ou t leav ing a V* in.

(6.35 m m ) t h i ck wa l l . T h e cyc l i n d e r s

we re then cu t pe rpend icu la r to the

we lds and rad iographed to revea l the

ex ten t o f po ros i t y . The rad iographs

were judg ed fo r seve r i t y of po ros i t y

on a sca le o f 1 to 5 . Weld s f ree o f

de tec tab le po ros i t y (de tec tab i l i t y l i m

i ts 0 .010 in . (0 .254 mm ) d iam ) we re

ra ted as 1. We ld s w i th 5 o r mo re vo id s

per inch o f w e l d , grea ter than 0 .025 in .

(0 .635 mm) d iam we re ra ted as 5 . The

o the r ra t ings we re even ly spaced in

b e t w e e n .

The same we lds we re ra ted

fo r su r fac e roug hne ss on a sca le o f 1

to 5 w i th 1 be ing the smoo thes t s u r

face. We lds w i th ra t ings o f 1 , 3 , an d 5

are sho wn in F ig. 1 .

Du r ing GTA we ld ing on ce r ta in lo ts

o f HMSS, much e r ra t i c f l a sh ing and

some expu ls ion o f mo l ten ma te r ia l

5 4 8 -s I D E C E M B E R 1 9 7 4


2/6

Table 1 — Chemis try L imi ts High

Mn

Sta in less S tee l

Element

Chromium

Nickel

Manganese

Silicon

Nitrogen

Phosphorous

Carbon

Sulfur

wt%

18.00-21.00

5.50- 7.50

8.0 -10.0

1.00 Max.

0.15- 0.40

0.060

Max.

0.040

Max.

0.030

Max.

'..

T a b l e 2 — S t a n d a r d W e l d i n g

Conditions

Fig. 1 — Extent of surface roughness variations with respective ratings

Weld current

Electrode type

Electrode gap

Torch gas

Welding speed

200A(dcsp)

EWTh-2 - 3/32 in.

diam

0.060

in.

20

cfh Ar

5 ipm

f rom the weld pool occurred. When

other lots of ma terial were

welded,

the

arc was very stable with no flashing or

expulsion. This f lashing and expul

sion is referred to here as arc insta

bility. The arc stability was rated as

good (G), fair (F), or poor (P) based

solely on the judgment of the oper

ator. In welds showing high instabil

i ty, a deposit slowly for me d on the tip

of the electrode. In some cases this

deposit grew to rather large propor

tions. Figure 2 shows some of the

more extreme deposits encountered.

These deposits occurred after ap

proximately 28 linear in. (711 mm) of

weld at arc currents of 150 A. The

tendency for deposit formation was

also rated as good, fair, or poor.

Supplementary in format ion has

also been obtained on both auto

genous and fi l ler metal addition w elds

over a wide variety of conditions. Th is

information wil l be discussed where

appropriate in the fol lowing sections.

Results and Discussion

The results of porosity, surface

roughness and arc stabi l i ty measure

ments are shown in Table 3. Several

items stand out in reviewing Table 3.

First, any one measure of weldability

is a good indicator of the other three.

Second, airmelt

material produces

consistently poor results. Third, in the

remelted

heats, poor weldability is

associated with high nitrogen con

tent. Fourth, the electrode bui ldup oc

curs when the other instabi l i t ies are

significant.

The arc instabi l i t ies appear much

like momentary short-circuit ing of the

electrode to the weld pool; violent

f lashing,

expulsion of metal and often

a loud popping sound. However ,

there is no pickup of tungsten inclu

sions in the weld metal and apparent-

Fig. 3 — Backscattered electron

micro-

graph of electrode buildup.

X100

reduced

38%

Fig. 2 — Buildup on 3/32 diam electrodes

T a b l e 3 —

Hea t

no.

81143

81698

81942

1X0555

8 2 2 8 7

( a )

82289

85598

6711

6818

7012 -1

692394

6 8 0 6 9 3

< a )

Welds mac

034037 <

a

>

039038

(a)

C h e m i s t r y

Mel t

type

VAR

ESR

Air

a n d W e l d a b i l i ty T e s t R e s u l t s o f G e n e r a l H e a t s of H M S S

N

c o n t e n t ,

w t %

0.30

0.22

0.28

0.40

0.25

0.22

0.28

0.34

0.39

0.20

0.38

0.29

le w i th adde d f i l l e r me ta l

Ai r 0 .36

0.38

O

c o n t e n t ,

ppm

75

55

3 0 - 1 3 5

30

30

175

260

320

Por

os i ty

ra t ing

1

1

1

5

1

1

1

2-3

2-3

1

5

4

4

5

R o u g h

ness

ra t ing

2

2

2

5

1

1

1

2

3-4

1

5

4

Arc

s t a

bi l i ty

G

G

G

P

G

G

G

F

P

G

P

P

Elec

t r o d e

bu i l dup

G

G

G

F

G

G

G

F

P

G

F

F

6818W

(a)

ESR

0.38

30

(a) Measu rements are from specific hardware weldments not standard test bars.

Tab le 4 — Ni trogen Loss Dur ing W e ld ing, wt %

Hea t

no.

1X0555

81143

6711

6818

82289

Me l t

type

VAR

V A R

ESR

ESR

ESR

N c o n t e n t

base me ta l

0.40

0.30

0.34

0.39

0.22

N c o n t e n t

we ld me ta l

0.35

0.26

0.25

0.26

0.20

Net loss

of n i t rogen

0.05

0.04

0.09

0.13

0.02

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

5 4 9 - s


3/6

' ; . - . ; •• , ' . : ' . ; . • ' • > • ' • •

Fig. 4 — Typical inclusion level in an

airmelt

steel. X100, reduced

27%

Fig. 5 — Typ ical inclusion level in an ESR steel. X100, reduce d

27%

Fig. 6 — Fine dispersion of inclusions viewed under differential in-

terference contrast lighting. X440, reduced 27%

Fig. Typical fusion zone shapes

for a

low D/W and a high D/W

steel. X2, reduced 27%

ly no actua l contact o f the we ld meta l

a n d t h e e l e c t r o d e . T h e e l e c t r o d e

bu i ldup has been ana lyzed by m ic ro -

p r o b e .

F igu re 3 i s a b ack sca t te red

e l e c t r o n m i c r o g r a p h of a t yp i c a l

r e g i o n o f t h i s d e p o s i t . T h e l i gh t

co lo re d phas e i s tungs ten and the

dar k m atr ix is a mi xtu re o f Fe , Cr, an d

N i w i th a t race o f S i . The me d iu m

co l o r e d r e g i o n su r r o u n d i n g t h e t u n g

s ten pa r t i c les i s a m ix tu re o f these two

phases.

An add i t i ona l aspect o f we ldab i l i t y

is tha t a second pass made over a

w e l d w h i ch p r e v i o u s l y sh o w e d h i gh

instab i l i ty is stab le and the surface is

s m o o t h .

Tab le 4 g ives n i t rogen loss

du r ing we ld ing fo r seve ra l hea ts .

A l though there is n i t rogen loss in a l l

cases, the losses are h igher in the

h igh n i t rogen hea ts .

These obse rva t ions suggest tha t a

la rge quant i ty o f n i t rogen is leaving

the we ld

p o o l .

Th is vapo r ca r r ies f i ne

d rop le ts o f mo l ten s tee l to the e lec

t rode c rea t ing the e lec t rode depos i t .

Th is d rop le t l aden gas s t ream may ac t

as a low res is tance cu r ren t pa th g iv

i n g t h e a p p e a r a n ce o f a m o m e n t a r y

short c i rcu i t . The arc instab i l i ty and

depos i t occu r on ly in the h igh n i t ro

gen hea ts , n i t rogen >0 .3 w t%, and a re

mu ch wo rse in those w i th n i t rog en

> 0 . 3 5 w t % .

Brooks (Ref . 1 ) has stud ied surface

cond i t ion and expu ls ion o f e lec t ron

beam we lds ve rsus n i t rogen con ten t

in HMSS and f inds poo r su r face c o n

d i t ion and expu ls ion a re assoc ia ted

w i th h igh n i t rogen leve ls . He a t t r ib

u tes th is behav io r to dec om pos i t i on o f

ch romium n i t r i de inc lus ions . A l l o f h i s

samp les we re a t the ex t remes, bo th

h igh and low , o f the n i t rogen con ten t

fo r th is a l loy.

W e h av e e x a m i n e d t h e m i c r o -

s t ruc tu re o f a number o f hea ts o f

HMSS to de te rm ine the re la t ionsh ip

be tween inc lus ion leve ls and GTA

we ldab i l i t y . A typ ica l i nc lus ion leve l

fo r an a i rm el t h eat is sho wn in F ig. 4 ,

wh i le F ig . 5 show s a typ ica l i nc lus ion

leve l in an ESR heat . The a i rmel t heat

con ta ins 175 ppm oxygen wh i le the

ESR hea t con ta ins 30 ppm oxygen .

M i c r o p r o b e a n a l ys i s ha s sh o w n t h e se

inclusions to be o f th ree types; (a ) en

r iched in Mn and S, (b ) enr iched in

M n ,

A l ,

and S i , and (c) enr iched in Al

on ly . The las t two types a re assumed

to be ox ides and the re i s gene ra l

agreemen t be tween inc lus ion con ten t

and oxygen leve l .

In heats w i th h igh n i t rogen c o n

ten t , a d i f fe ren t t ype o f i nc lus ion , a

f ine d ispe rs ion o f sma l l pa r t i c les , oc

c u r s , as is shown in F ig. 6 . We have

been unab le to iden t i f y these pa r t i c les

due to the i r smal l s ize , bu t Brooks

(Ref. 1 ) has ident i f ied s imi la r part ic les

as ch rom ium n i t r i des . Fu r the r , we

have seen them on ly in hea ts w i th

n i t rogen contents o f 0 .39 wt% or

h igher.

At these h igh n i t rogen leve ls, the

5 5 0 -s I D E C E M B E R 1 9 7 4


4/6

n i t r i de pa r t i c l es apparen t l y de

compose, relasing free nitrogen. The

porosity could be caused by nitrogen

entrapped in the l iquid or by nitrogen

be ing expe l l ed a t so l i d i f i ca t i on .

However, porosity is quite high in the

airmelt material even when nitrogen is

as low as 0.29 wt%. Further, airmelt

f i l ler metal also produces high por

osity welds (see Table 3). In airmelt

material the oxide inclusions may

break down, releasing oxygen and

adding to the porosity content. In the

remelted material porosity level cor

relates very well with nitrogen level

and porosity is virtual ly n onexistent

when nitrogen is below 0.30 wt%. The

extreme surface roughness of the

high nitrogen material is apparently

caused by agitation of the weld pool

as the nitrogen leaves the surface.

When a second pass is made over a

weld, the nitrogen level is lower, the

nitrogen evolved is much less, and the

weld surface is smooth and quiet.

D e p t h t o W i d t h

R a t i o V a r i a t i o n s

Another interesting aspect of GTA

welding of this alloy has been a large

variation in depth of penetration and

depth to width ratio (D/W) in auto

genous welds. Figure 7 shows the

cross section of welds made at the

cond itions de scribed in Table 2 in two

different heats. Several investigators

(Refs.

2-4) have reported similar var i

ations in fusion zone geometry. Gen

era l l y these inves t igat ions have

related change in geometry with a

change in impurity chemistry, but

have not resulted in a clear-cut ex

planation for the variations. We have

run a numbe r of experiments to t ry to

find a cause for such behavior.

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

Autogenous GTA welds have been

made on sol id bars as described

before, under the conditions of Table

2. In addition, arc lengths have been

varied from 0.040 to 0.100 in. (1.01 to

2.54 mm), welding speeds from 5 to

20 ipm (127 to 508 mm/min) and

torch gas mixtures of 25, 50, and 75%

He (balance Ar) have been used.

These welds were then sectioned and

the depth and width measured.

Several types of chemical

anal

yses have been used to determ ine the

chemical composition of each heat.

The major metal l ic al loying elements

have been analyzed using x-ray f lu

orescence. Oxygen and nitrogen have

been analyzed by inert gas fusion.

Metal l ic impurit ies have been ana

lyzed by emission spectroscopy and

spark source mass spectroscopy.

Aluminum content has also been

measured by atomic absorpt ion spe c

troscopy.

Spectral analysis of welding arcs

was performed in two ways. A GTA

welding torch was mou nted ins ide the

arc chamber of a standard 3 meter

analytical spectrograph and arc spec

t ra were reco rded us i ng pho to

graphic plates. This technique ana

lyzed l ight from the entire arc. To

analyze light from a specific region of

the arc a monochrometer was set up

with imaging optics at the inlet slit to

focus l ight from a specif ic region into

the sl i t. The resulting spectra were

then recorded photographical ly at the

exit.

R e s u l t s a n d D i s c u s s i o n

Table 5 gives D/W for welds made

per conditions of Table 2. The extent

of the variations is clearly shown in

this table. Several surface prepara

tions (as received, freshly machined,

degreased with acetone, etched with

inhibited HN0

3

) have been used on an

ESR heat and a VAR heat with no

change in response. Weld samples

have been taken f rom d i f fe rent

regions within a bar or plate and again

the results are the same. At low

welding currents (


5/6

m i n u m .

No o the r im pu r i t y o r a l loy ing

e lemen ts show any cons is ten t re la

t i o n sh i p t o D / W . T h e a l u m i n u m c o n

ten ts and D/W's are given in Tab le 7 .

T h e se a l u m i n u m va l u e s a r e m e a

su r e d b y a t o m i c a b so r p t i o n sp e c

t roscopy and a re the to ta l o f so lub le

p l u s i n so l u b l e a l u m i n u m . T h e va r i o u s

hea ts fa l l i n to two groups; those w i th

D /W's c lus te red a round 0 .5 and those

c lus te red a round 0 .25 . Fu r the r , a l l the

low D /W hea ts a re ESR p roces sed .

Hea t 6711 has a h ighe r D /W bu t was

remelted by a s l igh t ly d i f fe ren t ESR

m e t h o d w h i ch m i n i m i ze s a l u m i n u m

p ick up and it does ind eed have a

lowe r a lum inum con ten t . The f lux

used in most ESR ope ra t ions i s a

co m b i n a t i o n o f C a O ,

C aF

2

a n d

A l

2

0

3

.

I t has been shown tha t i t is possib le to

increase the Al con ten t to seve ra l

t imes the in i t i a l me l t amoun t by reac

t ion w i th the A l

2

0

3

(Ref. 5).

A fu r the r check on the e f fec t o f a l u

m i n u m w a s m a d e b y a d d i n g a l u

m inu m to a we ld po o l o f a heat o f stee l

p rod uc in g a h igh D /W. A n a rc and

mo l ten poo l we re es tab l i shed on a

ro ta t ing bar and a 0 .020 in . (0 .508

m m ) d i a m a l u m i n u m r o d w a s t o u ch e d

to the edge o f the

p o o l .

The we ld poo l

ins tan t l y w idened and the pene t ra

t i o n d e c r e a se d . T h i s b e h a v i o r p e r

s iste d fo r abou t V i in . (12 .7 mm ) o f

we ld a t we ld ing s peed s o f 5 ipm (127

m m / m i n ) . T h e w e l d t h e n r e t u r n e d t o

i t s o r ig ina l d ime ns io ns . Th is p ro

ce d u r e w a s r e p e a t e d m a n y t i m e s w i t h

a l u m i n u m a d d i t i o n s o f a b o u t Vz w t %

up to 4 w t%. Inc reas ing the am oun t o f

a lum inum d id no t change the we ld

d i m e n s i o n s i n t h e d o p e d a r e a .

Fu r the r , a lu m i num a dd i t io ns to 304

s ta in less s tee l p roduced no such

cha nge in a rc behav io r o r D /W .

S t i l l pho t ogr aph s have been m ade

of 100 A arcs wi th 0 .060 in . arc

l eng ths . Rep resen ta t i ve pho tos a re

sho wn in F ig. 9 . Photo 9A is an arc on

hea t 81698 , a VAR hea t wh ich p ro

duces a h igh D/W and Photo 9B is an

arc on heat 82289, an ESR heat w i th a

low D /W. No te tha t 81698 p ro duc es a

typ ica l a rc w i th no unusua l fea tu res

whi le the arc o f 82289 f la res out a t the

wo rkp iece . Fu r the r , a do m e of l i gh t

su r rounds the a rc . A lso , 81698 , when

doped w i th a lum inum as in F ig . 9C ,

takes on an appea rance nea r l y i d e n

t ica l to 82289. Th is dome o f l igh t

shows up on a l l the low D/W heats.

Co lo r pho tos show th is dome to be a

deep b lue .

In an a t temp t to be t te r unde rs tand

the behav io r o f va r ious e lemen ts in

the a rc , the l i gh t f ro m the a rc was a na

l yzed w i th the ana ly t i ca l spec t ro -

g r a p h m e n t i o n e d e a r l i e r . T h e h y

po thes is was tha t an e lemen t pecu

l ia r to these heats o f stee l might be

en te r ing the a rc in s ign i f i can t quan t i

t i e s and a l te r ing the cu r ren t dens i ty o f

o the r c r i t i ca l pa rame te r o f the a rc .

A rc spec t ra f rom d i f fe ren t hea ts o f

s t e el w e r e r e co r d e d o n p h o t o g r a p h i c

p la tes and the va r ious e lemen ts p res

ent were ident i f ied by use o f ava i l

ab le s tanda rd p la tes p lus the MIT

wave length tab les . A l l ma jo r l i nes

we re ident i f ied as e i ther a rg on or

manganese . The in tens i t i es o f the im

pur i ty e lement l ines were in a l l cases

much less than a l l bu t the ve ry weak

l ines o f these two e lemen ts . Th is in

d ica tes tha t the impu r i t i e s do no t

a f fect the energy ba lance or o ther

p h y s i c a l p r o p e r t i e s o f t h e a r c

s ign i f i can t l y . A rough de te rm ina t ion o f

the abundance o f the a l loy e lemen ts

in the arc ind ica ted tha t they appear

in the o rde r o f the i r vapo r p ressu res :

M n , Cr, Fe, Ni.

S ince we ld behav io r seemed to be

co r re la ted w i th a lum inum con ten t , a

se t o f representa t ive l ines fo r the

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

were compared on th ree hea ts o f

me ta l a t two d i f fe ren t a rc c u r ren ts .

T h e a ve r a ge l i n e i n t e n s i t i e s f r o m

t h r e e e xp o su r e s m a d e a s t h e sa m p l e s

were ro ta ted a t a su r face s peed o f

5 ipm (127 mm/min ) a re show in

Tab le 8 .

These da ta ind ica te tha t the

v a r i

at ion o f a lu m inu m in the arc does not

d i f fe r s ign i f i can t l y f rom the va r ia t ion

of the major a l loy const i tuents in the

a rc . The re fo re , the a lum inum is no t

expected to have any more d i rec t

e f fect on the physics o f the arc than

m a n ga n e se o r ch r o m i u m .

Examina t ion o f a rcs w i th the mono -

chrometer sys tem showed tha t the

deep b lue l i gh t (descr ibed above ) i s

ch a r a c t e r i s t i c m a n ga n e se e m i ss i o n

and tha t a sma l l am oun t o f em iss ion

f r o m a d d e d a l u m i n u m i s o b se r ve d a t

the su r face o f the pudd le .

F i gu r e 1 0 sh o w s t h e sp e c t r u m

(be tween 3800 and 4400 angst roms)

o f l i gh t em i t ted f rom the a rea im

med ia te ly above the mo l ten poo l on a

low D /W hea t . F igu re 11 sh o w s t h e

sam e in fo rma t ion fo r a h igh D /W hea t .

The arcs in F igs. 10 , 11 , an d 12 we re

all run at 100 A, 0.060 in. (1.5 m m )

a rc leng th and 5 ipm (127 m m /m in )

we ld ing speed . The leng th o f the

va r ious l i nes is a mea su re o f the w id th

o f the arc over wh ich exi ta t ion is tak

ing p lace.

Nearly al l of the l ines visib le in

these spec t ra a re due to manganese .

A com par ison o f F igs . 10 and 11 w i th

9A and 9B shows tha t the extent o f

m a n ga n e se e m i ss i o n co r r e sp o n d s t o

the f la re o f b r igh t l igh t a t the work-

p iece su r face . Fo r compar ison , F ig .

12 shows the same spect ra l reg ion fo r

an arc on 304 sta in less stee l wh ich is

qu i te s im i la r to F ig. 11 . Th is is in go od

a g r e e m e n t w i t h t h e ir c o m p a r a t i ve

we ld ing behav io r .

The spec t ra l i n fo rma t ion p lus o the r

e xp e r i m e n t s d i scu sse d i n d i ca t e s t h a t

a l u m i n u m a n d m a n ga n e se so m e h o w

work in comb ina t ion to decrease the

D/W ra t io o f we lds in heats w i th

h ighe r a lum inum con ten t . The de ta i l s

o f such an in te rac t ion a re no t unde r

s t o o d , bu t a re curren t ly the sub ject o f

fu r the r inves t iga t ion .

C o n c l u s i o n s

1. The GTA we ld in g beh av io r o f

HMSS is qu i te va r iab le and can be

s ign i f i can t l y d i f fe ren t f rom tha t o f the

more conven t iona l aus ten i t i c s ta in

less stee ls.

2. P o r o s i t y , s u r f a c e r o u g h n e s s ,

and arc stab i l i ty o f VAR and ESR

HMSS we lds a re s t rong ly re la ted to

n i t rogen leve l . These we ld p rope r t ies

wi l l be opt imized i f n i t rogen content is

Fig. 9 — Typical arc appearance for a high D/W steel (left), a low D/W steel (center), and a high D/W steel doped with aluminum (right)

5 5 2 - s I D E C E M B E R 1 9 7 4


6/6

Fig.

10

— Region of spectrum from

a

weld

on a low D/W steel

kept at 0.30 wt% or less.

3. Porosity and surface roughness

of welds in airmelt HMSS are worse

than

in

remelted material and appar

ently are related to both nitrogen level

and oxide inclusion level.

4.

We lds in ESR ma terial may have

much lower penetration and lower

D/W than VAR and airmelt material.

5. The lower D/W of ESR welds is

related to a higher Al content in the

ESR m aterial and seems to be caused

by some as yet undefined interaction

between aluminum and manganese.

Acknowledgments

The authors wish to acknowledge the

assistance of Mr. R. F. Hillyer and Mr. D. H.

Riefenberg for the analysis of inclusions

and electrode deposits reported. Further,

thanks are extended to Mr. R. Acton of

Sandia Laboratories

for

the thermal

di f fu

sivity measurements.

The work was performe d under Con

tract AT(29-1)-1106 for the Albuquerque

T a b l e 8 -

- R e l a t i v e In t e n s i t i e s

o

R e p r e s e n t a t i v e

Di f f e r e n t S t e e l Sa

S a m p l e

no.

81143

82289

6 8 1 8

81143

82289

6818

mples

A r c

c u r r e n t ,

75

75

75

40

40

4 0

A Mn

2.7

10.6

6.4

2.0

4.0

3.2

L i n e s

or

Fe

1.0

5.5

3.1

0.9

0.7

1.0

Cr

1.6

7.5

4.5

1.2

2.3

1.6

Al

0.16

1.5

0 .20

0.23

2.0

0.46

Fig.

11

— Region of spectrum from a weld

on a high D/W steel

Operations Office of the

Energy Commission.

U.S. Atomic

References

1. Brook s, J. A., "Electron Beam Weld

ability of High Nitrogen Stainless Steel,"

SLL-73-0060, October 1973, Sandia Lab

oratories.

2. Ludwig, H. C, "Current Density and

Anode S pot Size in the Gas Tungsten A rc,"

Welding Journal, 47 5), May 1968, Res.

••

. • • • • .

• '• '

-

•

•• • - • • • • • • • ( ' • ' •

IBfe

•• ••••

,:'• •• '• • •'•• .^?'^VmM§SMWS>-k

• - - ' .

• • :

• • '-•

: . ; : i : -

:

:. : ••

• • ' ^ • • • - . ; • •

:

. . ; • ; .

•

:»:

> v s v • • ' • • • • ; • • • • ; , : . - .

.

:

. : - • • : 7 : \

:

-' ' •

\k

••

p ^

P ; • ' • -

:

. • :

Fig. 72 — Region of spectrum from a weld

on 304 stainless steel

Suppl. ,

234-3 to 240-s.

3. Chase, T. F., and Savage, W. F.,

"Effect of Anode Composit ion on Tung

sten Arc Characterist ics," Welding Jour

nal, 50 (11), Nov. 1971, Res. Suppl., 467-s

to 473-s.

4. Oyler, G. W., Matuszesk, R. A., and

Garr, C. R., "Why Some Heats of Stainless

Steel May Not Weld," Welding Journal,

46

(12),

Dec. 1967, 1006 to 1011.

5. Rundell, G. R., Simonds Steel Divi

sion,

Private Communication.

WRC

Bul le t in

No.

190

December 1973

F l u x e s a n d S l a g s

in

W e l d i n g '

byC.

E.Jackson

Prior to the publ icat ion of this inte rpre t ive repor t , users of covered electrode s,

submerged-arc and other f lux-control led welding processes hav e had ava i l ab l e

lit t le information

or

explana t ion

of

flux-slag tec hnolo gy.

In

spite

of

this lack

of

informat ion for the user , appl icat ion of welding processes ut i l izing f luxes has

been extens ive . The lack of ava i l ab l e in format ion has b e e n due in p a r t to the

propr i e t a ry n a tur e

of

f lux form ulat ions .

Prof.

J ack s o n ,

in his

interpre t ive repor t ,

has unvei led the secrecy to provide the reader wi th a comprehens ive r ev iew of the

formulat ion and funct ions of welding f luxes an d s lag s . It is hoped tha t a presen

tat ion of some of the pr inciples of we lding flux techno logy will provide an appre

ciation of improved quality

of weld

me ta l ob ta ined th rough s l ag /me ta l r eac t ions .

Publ icat ion of this pape r was spo nsored by the Interpre t ive Repo r ts Com mit tee

of the W elding Research Counci l . Th e pr ice

of

WRC B ulletin 190

is

$4.00 per copy.

Orders should be sent to the Welding Re search C ounci l, 345 Ea s t 47th Stree t , New

York, N.Y. 10017.

W E L D I N G R E S E A R C H S U PP L E M E NT

|

553 -s

gta weldability studies on high

Documents