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Stainless Steels:Filler Metal Descriptions
and Welding Data:
STAINLESS GAS FACT:The biggest selling gas mix inNorth America for MIG, stainless sheet metalapplications, is a tri-mix containing argon - helium andCO2. The weld reality. For most gage stainlessapplications, the tri-mix provides more disadvantagesthan benefits in contrast to a less costly two part mix,argon with 2 - 4% CO2.
Stainless Steel "MIG Gas Reality"
Fifteen years ago while working with AGA, a SwedishIndustrial gas manufacturer located in Ohio I carried outextensive, stainless MIG gas research. I found out aremarkable gas fact. If you take the helium out of the heliumtri-mix developed for stainless short circuit applications, youachieve remarkable advantages for thin gage stainless. From
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this research I developed an optimum gas mix for both shortcircuit and spray transfer stainless steels. Argon with 2- 4 %CO2.
STAINLESS SPRAY APPLICATIONS >0.080:For many years I have been advising the stainlessmanufacturing companies I dealt with to use argon with 2 - 4%CO2. This mix is superior to argon oxygen mixes for stainlessMIG spray or pulsed applications. In contrast to an argonoxygen mix, an argon 2 - 4 % CO2mix results in cleaner, (lessoxidized) welds on stainless applications > 5 mm, this is verybeneficial on multipass welds, welds in which porosity is aconcern, or welds in which the cosmetic appearence isimportant.With the argon - CO2 mix, you can expect cleaner welds andwelds with less weld porosity, also the carbon pickup of thisgas mix will not impact low carbon steel stainlessconsumables.
STAINLESS SHORT CIRCUIT APPLICATIONS
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WHAT IS STAINLESS?
STAINLESS COMES IN MANY FORMS IT CAN BE
A LOW COSTMETAL WITH A LITTLE CHROME A LOT OF IRON.
Austenitic Martensenitic and Ferritic.Austenitic Stainless Steels are the ones we are most familerwith. These chrome nickel steels, in contrast to the lower coststainless have more alloys and are "non magnetic" Exception,types 310 - 330
Austenitic steels. Grades 20-202-205-301-302-303-304-305-308-
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309-310-314-316-317-321-329-330-347-389-17 7PH- 17 4PH-PH15-7Mo-AM 350-AM 355 A 286.
304 (S30400) - 304L (S30403) - 316 (31600) - 316L (S31603) -347 (34700)
Austenitic Facts: Austenitic grades typically 18% chrome
8%nickel (18/8).Grades 301-302-304-305-308 usually welded with E308
18/8 grades used for machine parts exterior buildings andindustrial parts.
18/8 not to exceed 800F 426C service temperature.
Manganese grades of stainless "200" series similar to 18/8
grades. Manganese in this series is used for "extra strength"Welding the manganese grades usually use the E308L filler.|
Martensitic and Ferritic are commom grades that we dont wantto weld and if we do we weld with great caution.
Note when welding these grades the weld procedure focus willbe on HEAT treat
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STAINLESS INTERNATIONAL WIRE SPECS
US AWS A5.9 / UK BS2901 / Japan JIS Z3321/ ISO3581/ Germany DIN 8555 - 8556
UNS International filler metal numbers start withWXXXXX
TYPICAL
STAINL
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ESSFILLERMETAL
S
Stainless Filler Metal Information:
StainlessFiller
InternationalSpecs
ChemistryManufacturesdesignations
Applications
Electrode
E308
Germany SGX5 Cr Ni 19.9
ISO 23.12
UNS W30940
C 0.08Mn 1 - 2.5
Si 0.25-0.6Ni 9-11
Cr 19.5-22
Thyssen-ThermJ
Kobe-MGS
Lincoln L18.8Pacweld -PW176SS
Sanvik 19.9
E308 istypicallyused whenthe
corrosiveconditionsare notsevere
Electrode
E308L
(low
carbon)
Germany SGX2 Cr Ni 19.9
ISO 119.9L
UNS W30843
C 0.03Mn 1 - 2.5Si 0.25-0.6
Ni 9-11Cr 19.5-22
ESAB -OK16.10Thyssen -JE
Sandvik 19.9L
Note (L)the lowercarbon toavertcarbideprecipitation
Electrode
308LSi
ESAB- OK
16.12Thyssen - JESi
Sandvik19.9LSi
Filarc -PZ6061/6561
TREFIL2PPSG
Note Si or
HiSi The highsilicon
increases thearc stability
and the weldwetting, which
is importantfor the low
amp, sluggish,
short circuitwelds
Electrode
309
Germany SGX12 Cr Ni
22.12
ISO 23.12
C 0.012Mn 1 - 2.5
Si 0.25-0.6Ni 12-14
Cr 23-25
ESAB- OK16.53
Sandvik- 24.13Thyssen -
Therm 25.14
Used firwelding 309
and austeniticto ferritic
(carbon) steels
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UNS W30940
Electrode
309L
C 0.03Mn 1 - 2.5
SI 0.25-0.6Ni 12-14
Cr 23-25
Used for weldoverlay
applications orbutter passes.
Electrode
310H
C 0.10 -0.12
Cr 26Ni 22
(H) Hasminimum
carbon contentlower carbon
can causemicro
crackingcausing tensile
reductions
Electrode
310
Germany SG
X12CrNi 25.20
ISO 25.20
UNS W31040
C 0.08-0.15
Mn 1 - 2.5Si 0.25-0.6
Ni 20-22.5Cr 25-28
To weld 310
and 304 cladand stainless
overlay
For low or high temp, corrosive or
any critical applications alwaysconfirm electrode choice with wire
manufacturer.
Using ELC ensure weld gas has less
than 3% CO2.
A low co2 mix is less oxidizing than a
low oxygen mix.
For l;ow carbon base use low carbon
filler identified by EXXXL
Electrode
312
GermanySG 9250XRCUNS W31240
ISO 29.9
C 0.15
Mn 1 - 2.5Si 0.25-0.6
Ni 8-10Cr 28-32
Higher Ferrite.More "crackresistance"
than E309.
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Electrode
316
GermanySG9250ZRC
UNS W31640
ISO 19.12.2
C 0.08Mn 1 - 2.5
Si 0.25-0.6Ni 11-14
Cr 18-20Mo 2-3
ESAB- 16.35Thyssen -
Therm G.Sandvik
19.12.2
for 316 steelsand good for
"high temp"corrosion
resistance
Electrode
316L
Germany SG
X2 CrNiMo19.12
ISO 19.12.2LUNS W31643
C 0.03
Mn 1 - 2.5Si 0.25-0.6
Ni 11-14Cr 18-20
Mo 2-3
Electrode
317L
317 GermanySG CrNiMo
1813ISO 19.13.4
UNS W31740
317L UNS
31743
C 0.03Mn 1 - 2.5
Si 0.3-0.65Ni 13-15
Cr 18.5-20.5
Mo 3-4
Has moly toincrease the
tensilestrength. Has
excellentcorrosion
resistance andhigh temp
propertiesNote contains
considerableferrite which
can lowertoughness
properties.
Electrode
318
Germany SGX5
CrNiMoNb1912
Electrode
320
used forwelding
Carpenter 20plus 20Cb-3stainless
Electrode
321UNS W32140
C 0.07Mn 1.43
Si 0.58Ni 10.52
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Cr 18.58
For weld data and information on CarbidePrecipitation scroll down to weld data
Electrode347
Germany SG
X5 CrNiHb
1999UNS W34740ISO 19.9No
C 0.069
Mn 1.59
Si 0.49Ni 9.96Cr 20.82
ESAB 16.11
Thyssen Therm
H.Sandvik -19.9Nb
used for 321 -
347 bettercorrosion
resistance than308
E347-321 wireis stabilized
with smallamounts of Ti
or Cb toprevent
carbideprecipitation
Electrode349
UNS 34940
Electrode
410
Germany
SG 5 350UNS W41040
ISO 13-EZ13-189
Electrode
430
GermanySGS 250 Zr
ISO 17 - EZ17UNS W43040
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Welding High Strength, High Carbon
Steels withAustenitic Stainless or Nickel FillerMetals.
Austenitic and specific nickel filler metals can offer manywelding benefits for welding dissimilar joints.
In welding high strength, high carbon steels the austenitic /nickel filler metals offer unique features that can reduce weldcrack potential in both the welds and weld heat affected zone
(HAZ).
[1] High carbon to stainless welds require that the stainlessweld metal have sufficient ferrite to resist cracking. Whenwelding carbon steel to stainless and a 309Lwire is used, theresulting ferrite is approximately 14-16FN.
If the steel is a high carbon steel, a 309L, first weld pass on thecarbon to stainless will likely end up with "insufficient ferrite".The carbon from the high carbon steel when mixed with thestainless weld will suppress the ferrite formation. Instead of
the 309L for this application, a 312 electrode may berecommended.
The 312 filler metal, (70 to 90 FN in the weld metal) producesmuch higher ferrite levels than the 309L. This is the primereason the 312 is recommended for applications sensitive toweld cracks.Filler metals such as 307 - 308 Mo and 310 can
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resist cracking with the aid of alloys and without the aid offerrite.
[2] High carbon, high strength steels welded to each aresubject to hydrogen assisted cracking. [1] High hardness, [2] a
source of hydrogen and [3] high stresses, these are the threefundamental requirements for hydrogen assisted cracking.
[a] With the high carbon steels, high hardness is typical in theHAZ unless very high, (not practical) preheat and interpasstemperatures are utilized for the welds.
[b] The stresses that can influence HAZ cracking typicallyresult from weld residual stresses caused by weld shrinkage,these stresses can be further exaggerated by weld jointrestrictions as found in certain fixtures.
[c] As we are all aware hydrogen in the weld can be derivedfrom many sources.
An alternative to a high carbon, high strength filler metals, inwhich the carbon dilution from the base metal will result in ahard weld, subjecting the weld to transverse cracking, is anaustenitic or a specific nickel based filler metal (ENiCrFe-2).
The austenitic or nickel filler metals greatly reduces the weldtransverse cracking potential. Also these filler metals greatlyreduce, slow down or trap the weld hydrogen that can diffusefrom the weld into the HAZ, this greatly reduces HAZ hydrogencracking potential.
The diffusion of hydrogen though austenitic and nickel fillermetal welds and steel can be approximately 80 - 110 timesslower than through carbon steels and welds. The use of theaustenitic and nickel filler metals can greatly reduce crackinghowever these filler metals can still absorb hydrogen so theseelectrodes should be treated with the same respect and rulesthat apply to any low hydrogen filler metals.
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In North Americaand the World, Sanvik setsthe standard for MIG Stainless wires.
Excellent stainless gas shielded flux cored wires are
available from Alloy Rods and Kobleco.
ELIMINATE STAINLESS WELDPOROSITY:
Weld porosity, a cavity discontinuity that forms from a gas
reaction. The porosity can be trapped in the weld or at theweld surface. The porosity is typically round in shape but canalso be elongated
ROBOTS AND MIG POROSITY.When you find the robot weldporosity is always at the same location and the weld porosityis not at the weld starts or ends, examine the robot movementand see if the robot arm is causing a restriction of the gas flowline. Also it's common with robot cells to see a severe gas flowrestiction due to the narrow orrifice found in gas line
connections. In a robot cell its critical to measure gas flow asit exits the gun. If the porosity is at the weld start or stopincrease the gas pre flow and post flow times.
WELD POROSITY:Weld porosity, a cavity or discontinuity that forms in the weldfrom a gas reaction in molten metal.
The weld porosity can be trapped in the weld or evident at theweld surface. Weld porosity is typically round in shape, butcan also be elongated.
Weld porosity is caused by the absorption of oxygen, nitrogenand hydrogen into the molten weld pool. The gases are thenreleased on solidification and may become trapped in the weldmetal.
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Nitrogen and oxygen absorption in the weld pool usuallyoriginates from inadequate or contaminated gas shielding,leaks in the MIG gas line, excess gas flow rates, draughts andplate contamination.
Hydrogen can originate from a number of sources includingmoisture from the electrodes,moisture on the parts,contaminates on the workpiece surface.
CLUSTER WELD POROSITY. A localized groupof pores with random distribution. Causes. Arcblow, insufficient, inconsistent or excessive
weld gas flow, material or weld wire contamination, (low) weldparameters or poor technique.
PIPING, WORM HOLE, WAGGON TRACKS POROSITY.
Sometimes called "waggon tracks". Typically found in thecenter of the weld, parallel to weld axis. Classic porosity whenmoisture is evident in gas shielded flux cored wires, (thecheaper the product the more prone to waggon tracks).
Increasing the flux cored wire stick outand increasing the wire feed rate helps byadding energy to the wire. Baking fluxcored wires and storing the wires in a dryenvironment also reduces potential. Slow
weld speeds, make welds larger, avoid weaves. Allrecommendations are intended to increase the weld arcenergy and decrease the weld cooling rate.
Worm holes are elongated gas pores producing a herring boneappearance on a radiograph. Worm hole porosity is commonin gas shielded flux cored welds when the electrodes have toomuch moisture in the wire flux.
WELD ROOT POROSITY.Weld root porosity frequently occurs when MIG welding using"argon oxygen" (oxidizing) mixes on parts >6 mm. With thesegas mixes the resulting root is typically narrow, finger shaped.The root finger area solidifies rapidly trapping porosity. Toreduce the stainless root weld porosity, change to an argon 2 -4 CO2 gas mix. Increase the weld parameters, slow the weldspeed and avoid weld weaves.
ALIGNED WELD POROSITY. Linear porosity, an array of smallround pores typically found in a line. Often caused from thebase metal lubricants or metal surface contaminate. Add weld
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energy (increase wire feed), increase push angle allowing thearc to break up surface oxides ahead of weld.
SCATTERED WELD POROSITY. Weldporosity scattered randomly throughout the
weld or welds. If the MIG weld surface isgray and looks oxidized, the porosity istypically a result of insufficient gas flow. If
the weld surface looks clean with scattered porosity theporosity is usually caused by the base metal part or electrodecontamination, or perhaps the weld data used causes the weld
to freeze too rapidly.
LARGE PORE WELD POROSITY.If weld surfaceis clean and does not look oxidized, the largepore MIG / FCAW porosity could be a result of
excessive gas flow. Gas turbulence is caused with gas flowgreater than 40 cuft/hr. Optimum MIG and flux cored gas flowfor carbon steels is 25 to 35 cuft/hr, the gas flow should bemeasured as it exits the gun nozzle. If the weld surface is dirty(oxidized) the cause of larger pore porosity is ofen a result ofinsufficient gas flow, less than 20 cuft /hr.
Jan 2004. Sandvik Announces New Ultrahigh- Strength
Stainless Steel "NANOFLEX":
Sandvik Materials Technology recently developed anew stainless steel called Sandvik Nanoflexthatfeatures ultrahigh strength and good formability,corrosion resistance, and surface finish. According tothe company, the steel is well suited for mechanicalapplications requiring lightweight, rigid designs suchas medical equipment and for replacement of hard-
chromed, low-alloy steels in the automotive industry.
Examples of the strength properties of Sandvik Nanoflex are 1700 MPatensile strength, 1500 MPa yield strength, 8% elongation, 45-58 HRC
hardness, and a Charpy V impact strength of a minimum of 27 J at -20C.Exact strength values depend on the product form and the manufacturing
route.
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Despite its high hardness, the company claims it is easy to perform coldforming operations such as bending, cutting, turning, and grinding. After
reaching the desired shape, a simple low-temperature heat treatment givesthe material its high strength without distorting the workpiece.
This material also displays good welding properties. It isavailable in tube, strip, wire, and bar forms.
Stainless Filler Metal SelectionStainless Type FILLER METAL
SELECTIONAWS A5-9. Usefirst choice.
Confirm choicewith wiremanufacturer
AUSTENITIC CHROME NICKELNONE MAGNETIC
Stainless 201to austenitic 200-300series use
201 used for low temp cryoapplications to -320F
308For 330 use 312
Stainless 202 to austenitic 200-300series use
308For 330 use 312
Stainless 201-202-301 303 to mildsteel use
312
Stainless 210 - 202 -301 to mildsteel use
312
Stainless 301to austenitic 200-300series use
308For 330 use 312
Stainless 302to austenitic 200-300
series use
308
For 330 use 312Stainless 302 - 302b 304 to mildsteel use
310
Stainless 302 - 302B -304 to mildsteel use
310
Stainless 303to austenitic 200-300series use
308For 330 use 312
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Stainless 303 to 310-314-330- use 312
Stainless 303 to mild steel use 312
Stainless 304to austenitic 200-300series use
308For 330 use 312
Stainless 305308 to mild steel use 312
Stainless 305 to austenitic 200-300series use
308For 330 use 312
Stainless 305 - 308 to mild steeluse
312
Stainless 308to austenitic 200-300
series use
308
For 330 use 312
Stainless 309to 309 - 310 - 314 -316 - 317 use
309
Stainless 309 to 330 use 312
Stainless 309 to 347 use 308 - 347
Stainless 310to 310-3140 310
Stainless 310 to 316 use 316
Stainless 310 to 317 use 317
Stainless 310 to 321 use 308
Stainless 310 to 330 use 312
Stainless 310 to 347 use 308
Stainles 310 to mild steel use 310
Stainless 314to 314 use 310
Stainless 314 to 316 use 316
Stainless 314 to 317 use 317
Stainless 314 to 321 308
Stainless 314 to 330 use 312
Stainless 314 to 347 use 308
Stainless 314 to mild steel use 310
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Stainless 316to 316 - 317 use 316
Stainless 316 to 321 - 347 use 308
Stainless 316 to 330 312 - 309
Stainless 316L to mild steel use 309
Stainless 316LN a nitrogenaddition to a low carbon stainlessIncesase both corrosionresistance and strength ascompared to 316L
316L or 317L317L typical forcorrosion316L for toughness(cryogenic typeapplications
Stainless 317to 317 317
Stainless 317 to 321 308
Stainless 317 to 330 use 312
Stainless 317 to 347 use 308L
Stainless 317 - 321 - 348 403 - 405410 414 416 to mild steel use
309
Stainless 321to 321 - 347 347
Stainless 321 to 330 use 312 - 309
Stainless 330 to 330 use 330
Stainless330to 347 use 312 - 309
Stainless 348 347
Stainless 384 309
Stainless AM 350 AM 350
Stainless 410 Condition AASTM 27612% Chrome, chrominum /martensitic steel
to itself or carbon309L
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Stainless 501502 430 431 442 448to mild steel use
310
17-7PH use W17-7PH
PH15-7Mo use WPH 15-7Mo
17-4PH use 17-4PH
A286 A286
Sanicro 2827 Cr - 31 Ni -Mo 3.5 -Cu 1Tensile 73 ksi Yield 31 ksi
Sanvik 27.31.4.LCuER028L
Duplex Ferritic Austenitic
SAF 2304UNS 32304DIN X2CrNiN 24-423 Cr - 4 Ni - N 0.1Tensile 87 ksi - Yield 58 ksi
308 MoL
Duplex Ferritic AusteniticSAF 2205UNS S31803
22 Cr - 5.5 Ni -Mo 3 - NTensile 990 ksi - Yield 65 ksi
Weld Note: For MIG use argonwith 2% CO2. When welding 2205or 2304 to dissimilar butter firstwith ER309MoL then weld with308MoLNo concern for interpass temp,high amps can be use
2209
Duplex 3RE60
18.5 Cr - 4.9 Ni - 2.7 Mo weld same as 2205
254 SMO alloy
Electrode Avestap12Sanvik Sanicro 60ENiCrMo3
Stainless to carbon309 or 312 which hashi her ferrite
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reduces cracking
MARTENSITIC STEELS403 - 410 - 414416- 420- 422 -431- 440
Preheat and interpass temp 500F 260CPost heat 1350F 732C>Control cool 50F / hr to 1100F>Control cool to 1100F 600C then air cool.Treat the 500 series the same as theMartensitic series
Stainless 403 to 400 series use 410 ASTM 276
Stainless 403 to 501 use 502
Stainless 403 to 505 use 505Stainless 405 to 505 use 505
Stainless 405 to 501 use 502
Stainless 405 to 430 use 430 - 309
Stainless 405 to 400 series use 410
Stainless 410 to carbon steel 309L
Stainless 410 - 414 WELD same as405
Stainless 416 - 440 butter with 312or 309 first
Stainless 416 to 505 -502-501 -446- 440 -430 -420 use
309
Stainless 416 to 431-420-416 use 410
Stainless 420 to 505 505
Stainless 420 to 501-502 use 502
Stainless 420 to 446 use 430
Stainless 420 to 440 -420 use 420
Stainless 420 to 431 -430 use 410
Stainless 430 to 505 use 505
Stainless 430 to 501 - 502 use 502
Stainless 430 to 446 - 440 - 431 -430 use
430
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Stainless 430F to 400 series use 309
Stainless 431 to 505 use 505
Stainless 431 to 501 -502 use 502
Stainless 431 to 446-440 use 309
Stainless 440 weld same as 431
Stainless 446 to 505 use 505
Stainless 446 to 501 - 502 use 502
Stainless 446 to 446 use 309
Stainless 505 to 505 use 505
Stainless 501 to 505 - 502 - 501use
502
Stainless 502 to 505 - 502 use 502Ferritic steels 405 - 409 - 429 - 430-434 - 436 - 442 -444 - 446
444 to 444 or to other metal use 316L or 309MoL
Ferritic magnetic avoid prolongheat in the range of 750F -1700F(400-925C
Feritic preheat at 350F 176C Toimprove ductility
Ferritic steels most frequentelectrodes 309 - 310 - 312
Ferritic steel if post heat requireduse Austenitic filler
Stainless and Nitrogen PurgeGas Question.
Ed as you are aware Nitrogen is a lotcheaper than argon when utilized as apurge gas for stainless. My question,When MIG welding stainless tanksedge or corner welds, tube or pipe
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open root welds, can nitrogen react with the stainless andhave a negative impact?
Answer: Nitrogen typically a diatomic, "two atoms" permolecule. Nitrogen in the diatomic form is usually insoluble in
molten stainless. However if the nitrogen gets into the weldarc, the plasma arc energy can seperate the diatomicmolecules and create monatomic molecules.
The monatomic molecules are soluble in the weld. Thenitrogen, monatomic (seperated molecules) become analloying element and can reduce the ferrite in a stainless weld.A reduction in ferrite in some alloys can cause the weld to bemore austenitic and sensitive to hot cracking. If nitrogenenters a weld or the welding arc, it can have a negative andsometimes a positive influence.
There are stainless alloys which do not need ferrite like 320 /310. With these alloys nitrogen has no negative impact onthese alloys. Also if the stainless alloys have high ferrite levelsthey typically can afford to loose a little of the ferrite to thenitrogen.
With closed root, austenitic stainless welds, as found in tanks,corner, edge welds, or thin gage, partial penetration tubewelds, nitrogen is the logical, economical, purge gas choicefor all austenitic, duplex, martensitic and precipitationhardening stainless steel applications. The only concernwould be a few specific, ferritic alloys in which nitrogen couldcause severe weld mechanical issues.
With an open root "MIG stainless weld"the nitrogen purge gas has littleopportunity to get into the weld arc as thegas flow rate / pressure of the welding gasshould be higher than that of the purginggas . However nitrogen could still bepicked up by the weld. .
With duplex stainless there should be noconcerns for open root nitrogen issues.The majority of the common, open root
stainless alloys will not be adversely affected by nitrogenpurge gas. However in the world of product liability, here is thewelding bottom line. If your weld job is large enough toproduce a substantial cost reduction from using nitrogen gas,
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then it's logical to "pre qualify the nitrogen purge welds"andhave the weld chemistry, ferrite and mechanicals tested.
Failed Pipe Weld Tests.
Question: Ed we weld austenitic stainless and carbonsteel pipes. For cost reduction, in our stainless weldtests we only utilize "carbon steel pipes" and 309LSMAW or flux cored, electrodes. We frequently haveroot cracking issues, or during the bend test the weldsample breaks. What is strange is that we visuallyexamine all the roots and we wont let them bemechanically tested unless the welds look OK. Why
the inconsistency? why do some tests welds pass andother good looking welds fail?
Answer: The bottom line the 309L electrode is designed toweld "carbon steel to stainless" this electrode was notdesigned to weld carbon steel to carbon steel thats why wehave carbon steel electrodes.
Use the 309L electrode on two carbon steel pipes and welddilution becomes a concern in the weld root area. If the weldparameters and edge prep is such that the resulting weld
dilution is minimal, the resulting 309L weld should beaustenite with a little ferrite. It's the austenite / ferritecombination that provides weld ductility.
If while welding the carbon steel pipe root, the welder useshigher current, slower weld speeds or a wider weld weave, the309L weld can end up with more weld dilution with the carbonsteels, reducing the weld ferrite level and making the weld
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more austenitic. A reduction or loss of ferrite can make theweld subject to "hot centerline cracking" (hot cracking, theweld cracks during the weld or soon after).
A hot weld crack surface in a bend test can be identified by a
blue or gray color. Even if the root pass does not crack thehigh austenite composition can turn to martensite whencooling. The brittle martensite can readily fracture during thebend test. (a silver color or bright fracture surface).
The bottom line if you look at the costs involved in thestainless to carbon steel pipe weld test, it makes little sense touse two carbon steel pipes. Ensure for your weld test that oneof the test pipes is at least stainless.
StainlessWeld Data.
When MIG Welding stainless you can use the optimum MIGwire feed data recommended at this site for carbon steels. Theonly change that will be required is weld voltage. As stainlesswill use a low reactive gas mix, less weld volts will be required.For MIG stainless welds typically 2 - 3 lower volts are requiredthan that recommended for carbon steels.
Keep stainless clean, only use stainless wire brushes.
Manganese grades usually weld wiith a 308L
Welding XXXLensure filler is low carbon as designated XXXL
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With fixtures avoid carbon steels inclose proximity to stainless welds,as carbon pick up possible, the
weld area will rust. There are manyways to introduce carbon tostainless welds.For stainless vert up welds onparts 3 to 6 mm, consider pulsed,
For stainless all position welds on parts > 6 mm, first logicalchoice will be always be stainless gas shielded flux coredwires.
Minimize the drive roll tension applied to stainless flux cored
wires.
For stainless flux cored weld data, use the carbon steel fluxcored wire data found in my flux cored book.
For stainless flux cored use an argon mix with 15 - 25 CO2.
STAINLESS AND CARBIDE PRECIPITATION (chromedepletion):
Use weld data to avoid CarbidePrecipitation. (CP)
For stainless corrosive environmentscontrol of CP is critical.CP occurs with 300 series in thetemperature range of 800F - 1600F,430-870C.CP typically occurs within 3 mm ofeither side of a weld HAZIn the temperature range of 800-1600Fthe chrome will move to join carbon,
this results in "chrome depletion"leaving an area with less
chrome.
A chrome depleted area may not resist the corrosiveenvironment.
To combat CP use (L) low carbon base and filler metals.
Ensure the C02 gas composition has less than 5 % CO2.
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Stainless and stabilized electrodes.You can combat CP with stabilizedfillers which provide alloys that grabthe carbon before it can affectr thechrome. Alloys like E347 which work
at reducing chrome depletion.Stabilized fillers are typically used inhigh strength high temp service.However if base metal is not an Lgrade CP will occur.Rapid cooling of stainless through
the 800 - 1600F range reduces Carbide Precipitation.
TIG welding and the influenceof "sulfur" in austeniticstainless.When the parts to bewelded have normal sulfur content(greater than 0.005%) aninteresting event can occur. Withincreasing weld temperature thesurface tension of the weld poolalso increases. The result is the
hottest part of the fluid weld surface is attracted to the middle
of the weld pool causing deep narrow weld penetration.
With lower sulfur in the weld, the weld surface tension is less.The resulting weld is wider with less fusion. When two partswelded together have different levels of sulfur tension the weldmay pull towards the lower tension, lower sulfur part, resultingin inconsistent weld fusion or penetration favoring one side ofthe weld joint. This occurrence is especially notable whenautomated TIG welding Dissimilar parts such as cast parts tosheet or pipe. The following weld solutions may assist thesulfur issues.
[1] Pulse the application.[2] Use a weave.[3] Weld twice.[4] Use heat sink back up bars in close proximity to weld.
General Stainless (P-8) 300 Series Pipe Weld Procedure Data.Max interpass Temp 350F
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ProcessTungsten
Thoriated
Filler
DiameterMetal Polarity Amps
Wire
FeedVolts
GTAW 3/321/16 -
1.6mm
300
series
Stainless
DC
Straight95-145 N/A 14
SMAWEXXX-15-16
1/8
3.2mm
300
series
Stainless
DC
Reverse95-145 N/A 20-24
SMAWEXXX-15-16
5/32
4mm
300
series
Stainless
DC
Reverse125-175 N/A 21-25
FCAWEXXX-T1
argon with
25 CO2
045
300
series
Stainless
DC
Reverse
130-180
(140)230/280 22-25