welding stainless steels process
TRANSCRIPT
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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-
-
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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
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7 1 2 Waldlng Stainless Steel
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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
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71 4 Welding tainless teel
Othert
7_
6
P
10.0 Mn
6
P
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We/dability o Stain ess Steel 7.1-5
Fig 71
l
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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
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We/dability
o
Stainless Steel 7.1 7
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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
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; _
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
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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
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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
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7.1 12 Welding Stainless Stee/
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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
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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
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~ 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
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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
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7.1-18 We ding Stain ess Steel
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1.2 1
Welding Stainless
teels with
the hielded Metal Are
Process
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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
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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
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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.
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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
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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
~
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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
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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
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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
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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
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7.5 4 Welding Stainless Steel
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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 ~
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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
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Submerged Arc Process 7.3 3
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7.3 4 Weldmg Stainless Steel
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7.4 1
Welding Slainless Sleels with
lhe as
Metal Are Process
SPRAY ARC TRANSFER
l
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7_4 2 Welding tainless teel
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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
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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.
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Gas Metal Are Process 7.4 5
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7.4 6 Welding Stainless Steel