Welding Stainless Steels Process

7/26/2019 Welding Stainless Steels Process

1/42

SECTION 7.1

WELDABILITY

OF

STAINJ,ESS STEEL

Page

7.1-1

7.1-1

7.1-9

7.1-9

SECTION

7.2

7.1-10

7.1-12

7.1-13

7.1-13

7.1-H

7.1-14

7.1-16

1-1-16

WELDIXG STAINLESS STEELS WITH

TH.l ; SHIELDED METAL-ARC PltOCESS

Selectiug

Blectrodes.

. 7.2-2

Considerations in Welding . . . 7.2-4

Welding ProROCESS

Joint

Design

Welding 1'rocedures .

Weld

Rackup .

Indination

of

Work .

Welding Flux .

Welding Eledrodes

Welding Technique.

7.3-1

. 7.3-2

. 7.3-2

. 7.3-2

. 7.3-2

7.3-2

. 7.3-3

Section

7

WELDING ST INLESS STEEL

SECTION 7.4

WELDING

STAINLESS

STEELS

WITH

THE GAS

METAL-ARC

PROCESS

Spray-Are

Transfcr

_ .

Short-Circuiting

Transfl r

P u l ~ e d A r c Trausi cr

\Velding Electrodes .

Specia.l CunRiderations .

SECTION 7.5

.

7.4-

7.4

. 7.4

7.4

. 7.4-

W:ELDlNG

STAINLESS STEELS WITH

THE

GAS TUNGSTEN-ARC PROCESS

Electrodes

and

Gases .

\ ~ e l d i n g Rods.

W ~ l d i n g

Prucedures

.

Automatc GTA Welding.

Hot-Wire Welding

Muttiple-Eh.cirode Welding

. 7.5-

7.5-

. 7.5-

-. 7.5

7.5-

-


2/42


3/42

7.1 1

Weldability of tainless tee

about 0.04 percent

c a u s e ~

.:hromium carhide pre

cpitation

when

exposed

to temperatures

hetween

800 and

HlOO F.

This rlepletea

thD

matri.x in

~ h r o m i u m and reduces the corrosion resistance in

local area, leadin;:

to

inl.ergranular corn>5on

Si icon, in larger amounu ihan used in othe

alloys, increasca oxidution resistnce

at

high tenl

p e r a t u r e ~

Hulfur ami seienium impart free-machinin

charactcristics. Niobium , . ] ~ o call ... I columbium

tit.anium, and tant.alum additions stubilize carbide

and reduce H u ~ c e p t i b i l i t y to intergranular couoHion

ISI ST INLESS STEEL GR DES


4/42

7 1 2 Waldlng Stainless Steel


5/42

Weldability t Stainless Steel 7.1 3

TABLE 71. Correiation

ol

Specificafions

lor

Stainless Sfeels Conlinued)

Casi Alloys

e

1

-

1- -

r=--

50442

CB

30 A2g6

_ _ _ l _ - - ' ' c = ' c - c ~ , O ~ . ~ -

j_' _ _'

____:_ A : -

A296,

A35


6/42

71 4 Welding tainless teel

Othert

7_

6

P

10.0 Mn

6

P


7/42

We/dability o Stain ess Steel 7.1-5

Fig 71

l


8/42

7.1 6

elding

Stainless Steel

single

alues dencte m a ~ i J r v m porcen agc unless QlherwLOC noled.

Untes

ctlwrwisa oo:oo. utl1er gloments of all alloys l1sled lncltJde maxlmum contsnts nf 0 SI.

O

040% P n 0.0300 S Balance

is Fa


9/42

We/dability

o

Stainless Steel 7.1 7


10/42

7 1 8 Welding tainless teel

T SLE 7-. Typicat

C o m p o s i t i o ~ s

ol Miirtensitic Slairlless Steels

:composmon

( )

1 ' '

'

j j _ = ; ~ ~ _ ~ 2 5 2 ~ -

1

12.0-14.0

1 25 Mn. O 15 S min). 0.060 P. 0.60 Mo opt)

,

; ~ : ~

=

: : ~ i 1.25 Mn, O 060 P. O 15 Se rnin)

Duplex nfcgs

Steels

The duplex stainless

s\.eels typicully

consist

of a

micro5tmcture

of

ahout

50

percent

ferrite

and 50 percent

austenite

but may

range from 20

t< >

80 volume percent

ferrite

They

were developed

to pro

vide a

higher

strengttiTurrosion-

reHiatant- alternative to....the

300

series austenitic

stainless steels.

Compositinns

are modified

to

favor

the high

ferrite levels

by increasiug

the

chromium

tu 22-26%, increaaing mulybdenum to 2-5%, decreas

ing

the

nickel

to

4-8%

aud adding copper up to

2%.

These compositions, .

Table

7-8, p r o v i d ~ exr.ellcnt

resiatance to pitting, crevice corrosion and stress

corrosion

cracking.

These compositiuns

also provide

oseful m ~ c h u n i c l properties,

l able

7-9, over a

temperature

range from as low as 50 F to 500

with yield

strength

nearly twice thaL of wro1 1ght

austenitic otail'lless steel and duetility and toughness

approaching those of

austenitic

stainless steel. The

pretrred 50 percent ferrite - 50

percent austenite

microstrudure uf ihe duplex ~ t a i n l e 8 s steels is


11/42

; _

Weldabifity o Stainless Steel 7. 1 9

T BLE

7-8. Composiliorl ol

Duplex

S t a i r ~ l e s s

Steels

experimental duplex ~ l a i n l e ~ s steels u deter1nine

the effects of

filler

metal composilion and welding

a

type

304L stainli'SS steel

of

FN 4.5 hut. l ~ s

susceptible

than

a typc

304L

stainless steel of

FN

O. The two

experimental

duplex alloys identified s

21-9 and 2il-7 in 'fable 7-R were le&R susceptible to

weld metal hot cracking than the commercial duplex

stainless. Bot.h of these experimental allnys

are

< ~ 8 t l l t i . . l l . y

free

of

M

u and

Cu.

This leads the

belief

that

:Mo

anrl

Cu

form low

melting

with

iron which could

cause

Lhe hut.

s u ~ c e p t i b i l j t y .

pm.:edure

on

weld

properties

a:nd l1ot cracking WELDING THE ISI ST INLESS STEELS

tendenc.y. Metallographic examinatio n, tensile

tests,

Charpy impact

tests

and Varestraint

tests

were used

not

to evalnate

the welds

by

severa. investiga.tors.

the

Mechanical test results showed that when ferr.ite-

eontent

is

below 60 EFN (approJrimately 60%) in

nearly

matching

wt>ld deposits for alloys 255 and

~ 2 0 5 sufficient ductility and

toughness

would be

attained t pass

a

side b< lld test and provide

a

Charpy "V" notch energy of

20 ft-lhs

at

50"F.

Weld

deposits of

nearly makhing

compositions with

ferrite

conients ur OYt r ao EFN

(appro:ximately

30%)

providcd tensile strength and

yield

strength

equivalent

to

that

of

baae metal.

While

molybdenum

is added

to r o ~ i d e

r ~ s i s t a n c e

to

pitting and

crevice

rorrosion, high

l ~ v e l s

(4.0%

and over) cause embrittlcment

of

the deposit, even

for


12/42

7.1 10 Wefding Stainless Stee/

limitations

thut

require

cureful a t t ~ n t i o n r l u r i n ~

procesaing. Anst.enitic ~ t e e l s

h v ~

a h1gh coeIiciont

of

thermal

expansion - over 50 highEr

than

that

of

carbon

~ t e e l or

of

the

100-series alloys - which

d e m n d ~ maximum ~ r e tfl minimize disWrtion and

warping of wclded parts. Sorne of Lhcse alloys are

sus(:eptible to the formatiun of sigma

phase

whcn

expo&ed

to certain high

t e m p ~ r t u r e

ranges, which

can cause cracking und reduce corrosion r ~ a i ~ t a n c e

unrler

c ~ r t a i n

conditions. Welding can

als o

cause

carbde vrecipitatlon in sorne ~ t a i i l l : f f l s grades which

decrcases the corrosion resistance in sorne chemical

media.

errite and Sigma Phase

Austenitic stainless steels may be

susceptible tu

hot cracking (micro-fisSurin) if the

ferrite

t:ontent

in the weld metal is. not

properly

controll_ed.

This

problem

is

corrected by

u ~ i n g

electrodes

that

deposit

weld metal containing a small amount of ferrit..-.

Thus, recommended- electrodes for many Htandard

austenitic

grades may deposit weld metal that

contains 3

to

5% ferrit. llvt: n, tbough

tbe

same

grade base metal c u n ~ i n s no-fe:rrite. Since e r r i t ~

li magnetic, it s casily

detected

in :m otherw:ise

IlDrunagnetic weldment

Ferrite is best determiwd by measurernent

with

a magnetic instTument

caltbrated to

AWS A 1.2. It.

can

also be estnated from the c-omposition of the

base material

and

filler material

wilh

the u ~ e of

any of severa

constitution

diagrams.

The oldest

.of

these

is

tbe

19-tS Schaeffler

Diagram.

The

Cr

equivalent ( Cr +

%

Mo + 1.5 x

%

Si + 0.5

x Cb)

plotted

on the

horizontal

axis

and the

nicke] equivalent { Ni + 30 X C 0.;) X

Mn)

on

the vertical axis. Despite long u ~ e , the

Schaeffler Diagram is now outdnted because it does

not cunsider nitrogen

effects

and because it

has o-f

proVen possible

to

s t a b l i ~ h

agreement

among severa]

measures

as

to

the ferrite percent

in a given weld

metal.

An

i m p r o v ~ m e n t

on the

Schaeffler

Diagrsm

ia

the 1973 WRC-DeL


13/42

1

1

_\

eldabifity

o

tainfess teel

7 1 ~ 1 1

Fig.7-4.

Oelo c o n e l l ~ o n

dragram fe aJstenltic s t a ~ n . e s s steel weld


14/42

7.1 12 Welding Stainless Stee/


15/42

Weldabi ity o Stainless Steel 7.1 1:3

Ferritic Grades

These grades have what is me1allurgir.ally known

a

ferritk

mirrostructure. 'l'hey

are magnetic and

nnnhardcnable

hy heat treatment.. Typical applica-

automobilc trim und

rnufflcn, interiur

lectrode Selection Without Heat Treating

Ferritic or

martenaitio;...steel weldments

to

he

used in

the as-welded

condition

shou d he welded

with

E308,

E309,

or

E3HJ electrodes.

The

ductile

chrominm-nickel welds r e s i ~ i cracking from

ddor

nt8lion

nd impact

bett.er

than ifthe

wcld

and hcat

Hlicctocd zone wcre [)()th

brittle.

However, d i T e r e n c e ~

in thermal e pansion rates, weld

and

base metal


16/42

7.1 14 Weldng Stainless Steef

propert.ies ffi>JY require

chromium-typc clcctrode.

Duplex Stainless Steels

The

duplex

stainless attain

their

duplcx

structure of roughly 50 and 50 austenite

after an anncaling heat treatmenl or hul wurking.

Weld deposits in these alloys with matching filler

metals

solidify

and remain

mmrly

100%

ferrite. This

single plw.se deposit is mnch more su&eeptible

hot cracking than a

mixed

d ~ p o s i t of ferrite

auslenite.

A

post

weld

annealing

l . n n m ~ n l

o :auRe

the

ferrite to partly transform to austenite

and improve

the dnctility_ H o w e ~ e r

hot

cracking

normlly would occur

befare

t he h o>ai

l r e H L m ~ n i

could

be accomplished.

In many

cases,

t

would not

be acceptable

or

feasible lo

heat

treat the

entire

welded assembly.

Preheating and Postheating

- Austenilic

slululcss-steeh

are best wetded without

preheat except

to

reduce shrinkage stresses on thick

~ e c t i o n s

or reslrainedjuints. No preheat,

low

interpaas

t ~ m p e r a t u r e

or a

stringer-head tech:nique reduce

the

time the heat-affected

wne

in the s e n ~ i t i z i 1 1 J 5

range

{800-l60WF).

thereby reducing the amount of


17/42

~ L r c n g l . h e n P d

by a low-tempenttun (900 tu 1150'F)

heal. r . r e a l m ~ n t .

Precipitation hardcning is mcthod

of increasing hardness aod

strength

metal.

Although sorne

variatinns apply to

grades,

precipitation bardening

H

g e n ~ r a l l y accomplished

by a three-step heat

treatmcnt

consisting of solution

l.reatment, rapid cooling. and

c o n t r o l l ~ d

reheating

(aging)

The first step

(solutinn

heat treating) d h s o l v e ~

ccrtain elcnwnts such as copper, titanium, niobium,

and aluminum, t h a l _ a r ~ normally

insoluable

at

room

icmpemture.

1'llis mechanism might be ~ : o m p a r e d

with

thc

abilily

o hot water

tu dissolve more

salt

than can

cold

waler

The ~ e c o n d stcp

{quenching) eools

the

metal

ra]Jidly

to retain thc

solution cffcct

al room

temperatme.

'Fhia conditlun sumetimes called a

s u p e r ~ u l u r a t e d solid solution.

The

third

step involves

reheating-

of lhe super

saturaWd metal to a relutively low aging

temperature

(about

900"F

for sorne

grade>s 1p1ns

Aus1enitic Grades


19/42

heat exchangen v a l > E . ~ and high t ~ m p e r t u r e steam

lines

Weldability o Stainless Steel 7 1-17


20/42

7.1-18 We ding Stain ess Steel


21/42

1.2 1

Welding Stainless

teels with

the hielded Metal Are

Process


22/42

72 2 Welding tainless teel

SELE TING ELE TRODES

Mechanical properties of

stainless-steel v eld

mdul

usually are not as impmtant the chemical

compositin (Table 7-14)

and

the heat treatment.

l h e r ~

lli

little difference in mechanical propertieR

or

chemicRI

composition

hetween

the

DC

EXXX-

15) ~ n r l the AC-DC (EXXX-lG) weld deposits made

Vith

electrodes of the same

dass.

Typical mechanical

ofstaiillCHH-Hted weld

metal are

giv en

in


23/42

TABLE

7-14. Typical Compositions

ol SlainlessSieel Weld Metal

AWS

Compogl\ion ( )

Type

C 1 .

c

1

Nb (Cb)

~

~ ~ : ;

. .

TABLE 7-15. Typical Mechanical Properties

ot t a i r ~ l e s s t e e l

Weld

Melal

AWS Type

1 e n ~ ~ ~ ~ s ~ : ; g t h

00

Elongatlon

n

2in.( )

~

-- --

more care t-o

avoicl slag inclt1sions.

Thcso clectrodes

~ r e

recommenderi

for

horizontal

fillets

and fnr

al

fiat-position

welding.

EXXX-16

electrodos

are

also

\lRed

in

all

positions

by skilled

weldors.

Selecting

the

proper

electrode must bu done

with

care

because of the lar;e

nLJmlJ


24/42

7_2 4 Welding Stainless teel

TABLE 7 7

T y p i c < ~ l

Filiar Metells f,r D h ~ s l ~ l l a r Metal Joints

Austenitic Stainless

~ - ~

304L 1 308 309

J\l9S J10S 3 ; ~ ~ J16L

317 2 ~ ~ =

- - , = , ~ , _

= , + - - - - + - - + - - - + - + - - - - - ~ - - - + - - - - + -

1

CONSIDE TIONS IN WELDING

Cleaning

.l< or

high-quality

welds, joints must be

dean and d;... The choice of power b r u ~ h i n g

degreasing,

pickling, grinding, or msrely

wiping

depends 1.1pon the kind and amount of dirt. Sorne

specific recommendations

are;

l Remove moisture by heating or by

with

dry

air

beware

of

mniHlure

in

lino). Moisturc caJJ collect

overnight in high-humidity

3. Flame-beveling and machining

may

leave

n>ntaminants or

oxide films 1

hat

must be

removed.

4.

Avoid

zinc

COJltamination from b r u s h ~ ~ or

tools

that

have

heen

uRed

on galvani:r.ed steel.

UHe nnly

stainless-steel win< bruahliB

that

have been used

only on

s t a i n l ~ s s steel.

Welding Procedure

,Joint Design Accurate

fitup

and good

preparation are

necessary for good wtdd

minimum

disiortiun. Joint desig:ns are to

those dcscriUed for mild BteeL

For

butt

welds on

plate to

l/2-in.

thick,

the

beve

shuuld

b J a 60"

induded

angle for good

penetration and easy

slag

removaL On plate

owr

1/2-in. thid1. and up tD

1-1/2

in.

tlck,

a double bev.,J ;

r e ~ o m m e n d e d i f

the

welding

can

be

done from

both sidcs.

Fot buU

welds

over 1-in.

thick

that

m u ~ t be

done from

one

side, a

U-groove is used.

For

butt

welds in plate over

l-J/2

in. thick

that can

be

welded

from bnth sides,

a duuble U-gruuve is recommended.


25/42

Welding l . e c b n i q u ' ~

can

lwlp control

distortion.

\Veld

witb

low

current consistent

with

sufficient

penfltYaLion

tu

r e < : l u c ~

the heat

inpLJ\,

to the work

Table 7-lB). s t r i n g ~ r beads-11t a

higher

speed

ratht r than

wide heads

at

a slower speed.

f

weave

bcads nust be

made, limit the weave

to

2-112

times

the etectrode diameter.

Ol.l1er

means to

contml distortion a.-e:

IJse rigid fixt.ures

to

hold parts in < ~ l i g n m e n t .

Shielded Metal Are Procass 7.2 5

: : : ~ 7 5 . Bunenng' t&:hmque lor JOin c ; mtld steel

~ ' o r

prelwating

and postheating

information

HH J

Mction7-l .

Joining Stainless tmd Other Stecls:

lLl ~ o m e

applicativns,

stainless-stcel

weld-mcutl

s applied tu

mild steel: for example,

lining

mild-steel vessels

ur

t:ontainer

with

ijtainlcss steel.

fo'or such

applications,

stainless

electrodes

with

higher

alloy

content are

\13ed so

th


26/42


27/42

Shielded Metal Are Process 7.2 7

SIIIELDED METAL-ARC MANUAL)

A l S I 3 0 0 S e r i e < S t ~ l n l e . . Steels

=:- :=ce==---- - - - - - - - - - - - - - - - - -

SHIELDED M E T A L ~ R C MANUAL)

Al SI Seris

300

Stainler s t ~ ~ l

~ ~ ~ ~ - - - -

~

e

l >ockng

go

1/4

~


28/42

7.2-8 We ding Stainless Sfeel

\Vhen

stainless-steel

b

joined to mild steel, t h ~

mild steel is buttered with

stainlesB steel. This

technique consists oi dpositing a ]ayer of atainless

on the surfacc o the mild steel. then

complcting

the

joint wth

stainleas eleclrude, as illuslrated in

Flg. 7-5.

The

elec:trode

commonly

used for buttering

is F.309. 'fhiH tedmique is ahm u ~ e d for

joining

hurd-toweld or high-carbon steels

that

cannot

be

preheated.

J < ~ 3 8

Blectrmle is

used

l'or juinln(

> H J ~ 1 H n i t i ~

mnngancse

steel to

carhon steel

or

to

manganese

stt'el. However, for

cornpunents

that ITI\JSt be rep aced

periodically, such

as

dippcr

teeih,

a

mangauese

clectrode ia recommended because the stainless weld

is

more difficulLt torch

cut.

There

are

severa] methods for applying a stainless

sllrface to

mild

steel.

For

a

small area. overlapping

wcld beads

are used, Wl illustrated

in Fig.

76(a).

For larger

areas, staiuless

sheets are plug-welded to

the mild steel [log. 7-6(b}, or stainless

strips

are

attach


29/42

Electrodes and Gases

7.5 1

Welding

Stainless

Steels with

the as Tungsten rc Process

Welding Rods

\Velding

rods

(filler metal) J'or gas lungsten-ar,.

welding are specified in AWS Af>.9-8l, and Lheir

chemical compositions are shown in Table 4-20.

TlwrB

no

specificatino

forthe

mechani.,al

r o p e r t i e ~

of

the

weld metal. According

to

AWI:i A5.9-81

thc

c l s ~ i f i c t i o n

is on

the basis of

chPmical

composition

of

th"'

iillcr metal

manufactur ed. Meehanical

testl

have not

bE


30/42

7.5 2 Welding Stainless Stee/

tu thE has"

metal

of

corresponding

chcmica.l

I'Oropooit.ion

Welding rocedures

Typical procedures

for gas

tnngsten-arc

weldinr;

of

sLa.inless stee] are givcn in 'l'ablc 7-23.

Filler-metal

selection

is

very

important in

GT

welding and um mlly "pecifed

by the

design

engineer. f

no

class of filler

metal is

speclficd,

- Table

716 can

be 11sed

as

a general guide

to

filler

metal ~ e l e c t i o n .

When two dilferent

t.ypes of t a i n l e s s

steels

are

t o be

joined, Table

7-17

can

be

used

as

a guide.

However, the

tables should be

used

with

caution. Where

corrosive

conditions

are severe,

the

filler-metal selection

can

be very r i t i c a ~ as indicated

in the footnot.e to

Table

7-16

The

DC pQwer

~ o u r c e

for

gM

Lunghtcn-rc

welding must be a

variablevultage

typc,

and l t

is

recommended that

a highfrequen


31/42

1

1

AUTOMA TIC GTAW WELDING

Stainless

steels

are

readily welded

with

automatic

GTAW Are voltage is

propurtional

to are

lcngth

-

thna, a reliablc signa

can

be generated to

operate

automat.ic arc voltage control

cquipment.

Filler metal

may be used, or light-gagc material

ma.v

be juined

by Himple fusion of the

joint

e d g e ~ .

Wheu c o l d ~

filler

meil

is u ~ e d ,

it

is

always

added

to

the front

-

of

the puddle.

Hot Wire Welding

The

so-called

hot.wire

method ofwelding gives

greatly

increased deposition

ratBs

and

wf'lding

sp1 do..

The wire - which tra1ls thc torch,

S

i lustrated in

Fig. 7-13 -

is resistsnce heated by

a separat.e AC

1

1 power supp]y,

lt

ia fed through a contad tube and

extcnds beyond

ihe

tubo.

The

extension is resistance-

heated that t

approaches

ur read1e11 the melt.ing

Gas

Metal Are Process 7.5 3

hase

metal

and the AC power oupJIIY furniHheo.

a

targe portion

of the

energy

needed to

resistance

melt

the filler wire. The hot-wirl'

method

iH, in

cl feet,

an adaptation of the

long siidwut principie

u ~ e d in anllmerged-arc

and

aelf-shie\ded flux-cored

are welding. The wire u

sed

for hot-wire

GT A W

welding is usually 0.045-in. diametn Since the wire

is mclled - or very nearly melted - by ita own

power

sources,

the

deposition rate can

be contrvl Rd

almost independPntly

of

the

Using the GTAW

hot-wiru

rates up to

18

lb/hr

can

be

at

-100 to 500 amp DCI ;N {Table

greater

depositiun rates

can

be ubtained using an automatic

oscillated welding technique. Voltage control ia

e ~ ~ e n t i l

to achieve

control

uf

the

large pudlile

when

welding at high depoAition ratt'S.

For this

reason,

GTA hut-.oorire welding requires

t h ~

use

of

~ - o l i l l g c

cuntrol equipment.

Multiple Eiectrode Welding

i l ~ ~ ~ t ~ ~ f o ~ c i r ~ ~ ~ i ~ ~ ~ ; l i ~ ~ s w ~ ~

~ ~ ~ ~ ~ ~ ~

By

using cloHely ~ p c e d multiple

tungsten

electrodes,

the

welding speed

can also

be

increased

s u b s t . ~ n t i ~ l l y when

GTA\V we ding: stainles8-Meel

tuhing

or sheet.

Multiplc cleill_mhl prNctically

climinate

the problem

ofundercutting

l l t higl1 ~ p c P d s .

TABLE

7-25.

Typtcat Speeds and Deposition Rafes

with GT W HDI Wlre

Oeposition

lb/hr


32/42

7.5 4 Welding Stainless Steel


33/42

JOINT O SIGN

7.3 1

Welding

Stainless

Steels with

he Submerged-Arc

Process

l:mtted since weld hHcking is not. u s ~ d - Thc advantagc

of this

joint

design

is

that

it

requires

a

of ocdge preparativo,

yet

produces

weJ,-JH

qualily having- ~ d e q l l e pen.,lration

Single-V

groove

welds with

a root

face, Figure

7- Tb, are used with nonfusible backing for single

pass butt welds of 5/16-in. thickness or greater. Fur

most industrial applications, tho maximum thickness

is of

the

onl.,r of 1-114

Lo

1-1/2 in. Ruot face

dimensions

are

1/8

to

3/16 in.

This

joint design is

also

UsBd for

lwn-pll m wcldb wit.hnut

b a c k i n ~

whcre

plat.e

thickness

< Xceeds

5/8

in.

The

first

p a ~ s is

made in

the

V

of the joint,

Figt1re 7-Th- The work

is thcn turned

over

and

th

first pass bcomes the

backing

pass. n this position, the

finishing

pass is

made

on thc llat ~ i d c of the

joint

penetrating into

the rootofthe first pass. l herootface isapproximately

3/8

in.

for

l w n - p a ~ welds.

The doub\e-V groove butt, Figure 7-7d,

is the

basic joint desi;;n for Kubmerged-an; welding. A \ar.;e

root face is generally ued with this desig:n. Figure

Fig

lar submerged arc w ~ l d 1 n ~


34/42

7.3 2 Wefding Stainfess Steel

7 8

shows

a

typieal

double-V groovc wcld in

3 in.

3[)4 plate and d e ~ c r i b e s

the welding

se


35/42

Submerged Arc Process 7.3 3


36/42

7.3 4 Weldmg Stainless Steel


37/42

7.4 1

Welding Slainless Sleels with

lhe as

Metal Are Process

SPRAY ARC TRANSFER

l


38/42

7_4 2 Welding tainless teel


39/42

PULSED ARC TRANSFER

as

Metal Are Process 7.4 3

Pulsed CMA welding < haracteristicR are excellcnt

tranafer

with lowcr currellts. Thcre are many

advantageo

with thia

procesa

induding

low Rpatter,

pcnctrirrilm without

melt through and

excellent

operator appeal

WELDING ELECTRODES


40/42

7A-4 Welding Starn ess Steef

will he

ul>ta.iue_d at

a welding

\:llrtent

of

amp

llC:EP. F ~ u r e 7 12

i l l m t r _ a t ~ s

t.yPical

ra_te c:urves

f ~ r various stamless-

steel

Kas

~ z ~ ~ u ~

: ; ~ ~ n ~ ~ ~ ~ i ~ l ~ i ' ~ ~ : t : l ~ ~ ;

~ ~ i ~ d ~ :

minimum

current

minim11m

are

volt.agc must

also

be

obtained.

fhis 1s generully

betwccn

24 anct

31)

v

It increases

with

an increase in

current.

and

i8

h i K h e ~

for

helium

~ h i e l d i n g t.han for

argon or

arKon CO,

SPECI L CONSIDER TIONS

_______

.

-------

whcn wclding magnet

:> For uniform fusiun.

centered

over- the

joint.


41/42

Gas Metal Are Process 7.4 5


42/42

7.4 6 Welding Stainless Steel

Documents

Welding Stainless Steels Process