duplex stainless grade datasheet
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Duplex Stainless Steel
Characteristic properties• Goodtoverygoodresistancetouniformcorrosion• Goodtoverygoodresistancetopittingandcrevice
corrosion• Highresistancetostresscorrosioncracking
andcorrosionfatigue• Highmechanicalstrength• Goodabrasionanderosionresistance• Goodfatigueresistance• Highenergyabsorption• Lowthermalexpansion• Goodweldability
Applications• Pulpandpaperindustry• Desalinationplants• Flue-gascleaning• Cargotanksandpipesystemsinchemicaltankers• Seawatersystems• Firewallsandblastwallsonoffshoreplatforms• Bridges• Componentsforstructuraldesign• Storagetanks• Pressurevessels• Heatexchangers• Waterheaters• Rotors,impellersandshafts• Reinforcingbarsforconcretestructures
Steel grades
Outokumpu EN ASTM/UNS
LDX 2101® 1.4162 S321012304 1.4362 S32304LDX 2404™ 1.4662 S824412205 1.4462 S32205/S318034501 1.4501 S32760 2507 1.4410 S32750
Outokumpu International Chemical composition, % National steel designations, steel name steel No Typical values superseded by EN
EN ASTM/UNS C N Cr Ni Mo Others BS DIN NF SS
LDX 2101® 1.4162 S32101 0.03 0.22 21 1.5 0.3 5Mn – – – – 2304 1.4362 S32304 0.02 0.10 23 4.8 0.3 – – 1.4362 Z3 CN 23-04 Az 2327 LDX 2404™ 1.4662 S82441 0.02 0.27 24 3.6 1.6 3Mn – – – – 2205 1.4462 S32205* 0.02 0.17 22 5.7 3.1 – 318S13 1.4462 Z3 CND 22-05 Az 2377 4501 1.4501 S32760 0.02 0.25 25 7.0 3.8 W,Cu – – – – 2507 1.4410 S32750 0.02 0.27 25 7.0 4.0 – – – Z3 CND 25-06 Az 2328
4307 1.4307 304L 0.02 – 18 8.3 – – 304S11 1.4307 Z3 CN 18-10 2353 4404 1.4404 316L 0.02 – 17 11 2.1 – 316S11 1.4404 Z3 CND 17-11-02 2348 904L 1.4539 N08904 0.01 – 20 25 4.3 1.5Cu 904S13 1.4539 Z2 NCDU 25-20 2562 254 SMO® 1.4547 S31254 0.01 0.20 20 18 6.1 Cu – – – 2378
Chemical composition Table1
General characteristicsAustenitic-ferriticstainlesssteelalsoreferredtoasduplexstainlesssteels,combinemanyofthebeneficialpropertiesofferriticandausteniticsteels.Duetothehighcontentofchro-miumandnitrogen,andoftenalsomolybdenum,thesesteelsoffergoodresistancetolocalisedanduniformcorrosion.Theduplexmicrostructurecontributestothehighstrengthandhighresistancetostresscorrosioncracking.Duplexsteelshavegoodweldability. OutokumpuproducesawholerangeofduplexgradesfromtheleanalloyedLDX2101®uptothesuperduplexgrades2507and4501.ThispublicationpresentsthepropertiesofLDX2101®,2304,LDX2404™,2205and2507.Thepropertiesof4501isingeneraltermsverysimilartothoseof2507.Grade4501isdeliveredifspecified.
Chemical compositionThetypicalchemicalcompositionsofOutokumpugradesareshowninTable1.Thechemicalcompositionofaspecificsteelgrademayvaryslightlybetweendifferentnationalstan-dards.Therequiredstandardwillbefullymetasspecifiedontheorder.
* Also available as S31803
www.outokumpu.com
Aus
teni
tic
Dup
lex
2 Duplex Stainless Steel
MicrostructureThechemicalcompositionofduplexsteelsisbalancedtogiveapproximatelyequalamountsofferriteandausteniteinsolution-annealedcondition.Thehighertheannealingtemperaturethehighertheferritecontent. Duplexsteelsaremorepronetoprecipitationofsigmaphase,nitridesandcarbidesthancorrespondingausteniticsteels,causingembrittlementandreducedcorrosionresis-tance.Theformationofintermetallicphasessuchassigmaphaseoccursinthetemperaturerange600-950°Canddecompositionofferriteoccursintherange350-525°C(475°Cembrittlement). Exposuresatthesetemperaturesshouldthereforebeavoided.Inproperweldingandheat-treatmentoperationstheriskofembrittlementislow.However,certainrisksexist,forexampleatheattreatmentofthicksections,especiallyifthecoolingisslow. Figure1illustratestherelationbetweentimeandtem-peraturethatleadstoareductionoftheimpacttoughnesswith50%.Duetotheriskofembrittlement,theduplexsteelsshouldnotbeusedattemperaturesabove250-325°C.Themaximumtemperatureandstrengthvaluedependsongradeandthedesignrulesbeingused.
Mechanical propertiesTables2-4showthemechanicalpropertiesforflatrolledpro-ducts.DataaccordingtoEN10088andEN10028whenapplicable.LDX2404™isnotyetlistedinEN10088.Data
Fig. 1. Curves for reduction of impact toughness to 50% compared to solution annealed condition.
T emperature (°C)
1100
1000
900
800
700
600
500
400
300
0,01 0,1 1 10 100 1000
(36s) (6min) T ime (h )
2507
2205
2304
LDX 2101 ®
Mechanical properties at 20˚C Table2
Minimum values, Typical values according to EN 10088 P H C P (15mm) H (4mm) C (1mm)
LDX 2101® Proof strength Rp0.2 MPa 450 480 530 480 570 600Tensile strength Rm MPa 650 680 700 700 770 800Elongation A5 % 30 30 30/201 38 38 35Hardness HB 225 230 230
2304Proof strength Rp0.2 MPa 400 400 450 450 520 545Tensile strength Rm MPa 630 650 650 670 685 745Elongation A5 % 25 20 20 40 35 35Hardness HB 210 220 225
LDX 2404™*Proof strength Rp0.2 MPa 480 550 550 540 620 640Tensile strength Rm MPa 680 750 750 750 800 850Elongation A5 % 25 25 25/201 33 32 30Hardness HB, max 290 290 290 230
2205Proof strength Rp0.2 MPa 460 460 500 510 620 635Tensile strength Rm MPa 640 700 700 750 820 835Elongation A5 % 25 25 20 35 35 35Hardness HB 230 250 250
2507Proof strength Rp0.2 MPa 530 530 550 550 590 665Tensile strength Rm MPa 730 750 750 820 900 970Elongation A5 % 20 20 20 35 30 33Hardness HB 250 265 255
P = hot rolled plate. H = hot rolled strip. C = cold rolled coil and strip.* Mechanical properties according to AM 641. 1Refers to A80 for gauges less than 3 mm.
forLDX2404™correspondstotheinternalstandardAM641.Theallowabledesignvaluesmayvarybetweenproductforms.Theappropriatevaluesaregivenintherelevantspecifications.
3
LDX 2101® 2304 2205 2507 4404
Rp0.2 478 446 497 565 280Rm 696 689 767 802 578Fatigue strength 500 450 510 550 274
Duplex Stainless Steel
* Values from internal standard, AM 611** Values from internal standard, AM 641
LDX 2101®* 2304 LDX 2404™** 2205 2507
20°C 60 60 60 60 60 -40°C 27 40 40 40 40
Fatigue
Thehightensilestrengthofduplexsteelsalsoimplieshighfatiguestrength.Table5showstheresultofpulsatingtensilefatiguetests(R=min/max=0.1)inairatroomtempe-rature.Thefatiguestrengthhasbeenevaluatedat2million
LDX 2101®* 2304 LDX 2404™** 2205 2507 Rp0.2 Rm Rp0.2 Rm Rp0.2 Rm Rp0.2 Rm Rp0.2 Rm
100°C 380 590 330 540 385 615 360 590 450 680150°C 350 560 300 520 345 590 335 570 420 660200°C 330 540 280 500 325 575 315 550 400 640250°C 320 540 265 490 310 560 300 540 380 630
Impact toughness.Minimum values according to EN 10028, transverse direction, J Table3
Tensile properties at elevated temperatures.Minimum values according to EN 10028, MPa Table4
cyclesanda50%probabilityofrupture.Thetestwasmadeusingroundpolishedbars.Asshownbythetablethefatiguestrengthoftheduplexsteelscorrespondsapproximatelytotheproofstrengthofthematerial.
Fatique, pulsating tensile test, MPa Table5
* Values for hot rolled and cold rolled strip according to AM 611** Values from internal standard, AM 641
* Values may differ slightly between the diferent duplex gradesRT = Room temperature
Physical propertiesPhysicaldataaccordingtoEN10088applyforallourduplexsteels,seeTable6.
20°C 100°C 200°C 300°C
Density g/cm3 7.8Modulus of elasticity GPa 200 194 186 180Poissons ratio 0.3Linear expansion at (RT ➞ T)°C X10-6/°C – 13.0 13.5 14.0Thermal conductivity W/m°C 15 16 17 18Thermal capacity J/kg°C 500 530 560 590Electric resistivity µΩm 0.80 0.85 0.90 1.00
Typical values* Table6
4 Duplex Stainless Steel
Corrosion resistanceTheduplexsteelsprovideawiderangeofcorrosionresistanceinvariousenvironments.Foramoredetaileddescriptionoftheirresistance,seetheOutokumpuCorrosionHandbook.Abriefdescriptionfollowsbelowregardingtheirresistanceindifferenttypesofenvironments.
Uniform corrosion
Uniformcorrosionischaracterisedbyauniformattackonthesteelsurfacethathascomeintocontactwithacorrosivemedium.Thecorrosionresistanceisgenerallyconsideredgoodifthecorrosionrateislessthan0.1mm/year.Duetotheirhighchromiumcontent,duplexsteelsofferexcellentcorrosionresistanceinmanymedia. LDX2101®has,inmostcases,abetterresistancethan4307andinsomecasesasgoodas4404.2304isinmostcasesequivalentto4404,whiletheothermorehighly-alloyedduplexsteelsshowevenbetterresistance.
Sulphuric acidTheisocorrosiondiagraminsulphuricacidisshowninFigure2.Insulphuricacidcontaminatedbychlorideions,2205showsmuchbetterresistancethan4404andasimilarresistancetothatof904L,Figure3.
Hydrochloric acidStainlesssteelgradessuchas4307and4404haveverylimiteduseinhydrochloricacidbecauseoftheriskofuniformandlocalisedcorrosion.High-alloyedsteelssuchas2507andtosomeextentalso2205canbeusedindilutehydrochloricacid,Figure4.Pittingisnormallynotaproblemintheareabelowtheboundarylineintheisocorrosiondiagrambutcrevicesshouldbeavoided.
Nitric AcidInstronglyoxidisingacids,e.g.nitricacid,non-molybdenumalloyedsteelsareoftenmoreresistantthanthemolybdenumalloyedsteels.LDX2101®and2304aregoodalternativesbecauseoftheirhighchromiumcontentincombinationwithalowmolybdenumcontent.
Pitting and crevice corrosion
Theresistancetopittingandcrevicecorrosionincreaseswiththecontentofchromium,molybdenumandnitrogeninthesteel.Thisisoftenillustratedbythepittingresistanceequivalent(PRE)forthematerial,whichcanbecalculatedbyusingtheformula:PRE=%Cr+3.3x%Mo+16x%N.PREvaluesgivenfordifferentgradesarepresentedinTable7. ThePREvaluecanbeusedforaroughcomparisonbetweendifferentmaterials.Amuchmorereliablewayofrankingsteelsisaccordingtothecriticalpittingtemperature(CPT).ThereareseveralmethodsavailabletomeasureCPT.Theelectrochemicalmethod,usedbyOutokumpumakesitpossibletomeasuretheresistancetopittingwithoutinterferencefromcrevicecorrosion(ASTMG150).Theresultsaregivenasthecriticalpittingtemperature,CPT,atwhichpittingisinitiated.Thepittingcorrosionresistance
Temperature, °C
100
80
60
40
20
2507
2205
904L
4404 254 SMO
0 10 20 30 40
H2SO4 % +2000 ppm Cl-
®
Fig. 3. Isocorrosion curves, 0,1 mm/year, in sulphuric acid containing 2000 ppm chloride ions.
Fig. 2. Isocorrosion curves, 0.1 mm/year, in sulphuric acid.
Temperature, °C
140
120
100
80
60
40
20
2304
4404
2205
904L
2507
2507
4404
2205
0 20 40 60 80 100
H2SO4, weight-%
Boiling Point Curve
LDX2101
4307
®
Temperature, °C
120
100
80
60
40
200 1 2 3 4
HCI, weight-%
Boiling Point Curve
2507
2205
44042304
Fig. 4. Isocorrosion curves 0.1mm/year, in hydrochloric acid.
5
90
80
70
60
50
40
30
20
10
CPT, °C
4404 904L4307 4436 254 SMO ®2304 25072205LDX 2101 ® LDX 2404 ™
Duplex Stainless Steel
Fig. 5. Typical critical pitting corrosion temperatures (CPT) in 1M NaCl measured according to ASTM G150 using the Avesta Cell. Test surfaces wet ground to 320 mesh. CPT varies with product form and surface finish.
ofthesteelsinaground(P320mesh)conditionisshowninFigure5. Theactualvalueoftheasdeliveredsurfacemaydifferbetweenproductforms. Whenrankingtheresistancetocrevicecorrosion,itiscommontomeasureacriticaltemperatureatwhichcorrosionisinitiatedinawelldefinedsolution.Thetypicalcriticalcrevicecorrosiontemperatures(CCT)measuredin6%FeCl3+1%HClaccordingtoASTMG48MethodF,ispresentedinFigure6.Differentproductsanddifferentsurfacefinishes,e.g.millfinishsurfaces,mayshowCCTvaluesthatdifferfromthevaluesgiveninthefigure.Duetotheirdifferentalloyinglevels,thefiveduplexsteelsshowconsiderabledifferencesintheresistancetopittingandcrevicecorrosion.LDX2101®hasaresistancein-between4307and
Stress corrosion cracking
Conventionalausteniticstainlesssteelcanbeattackedbystresscorrosioncracking(SCC)inchlorideenvironmentsatelevatedtemperatures.Stainlesssteelsoftheduplextypearelesssusceptibletothistypeofcorrosion. DifferentmethodsareusedtorankstainlesssteelgradeswithregardtotheirresistancetoSCC.Theresultscanvarydependingonthemethodandtestingenvironment.Theresistancetostresscorrosioncrackinginachloridesolutionunderevaporativeconditionscanbedeterminedaccording
Steel grade PRE
4307 184404 24LDX 2101® 262304 26LDX 2404™ 33904L 342205 35254 SMO® 432507 43
PRE values for different austeniticand duplex grades. Table7
4404,2304isonalevelwithconventionalmolybdenum-alloyedsteelsofthe4404type,whileLDX2404™and2205isonalevelwith904Land2507with254SMO®.
Fig. 6. Typical critical crevice corrosion temperature (CCT) according to ASTM G48 Method F. Test surfaces dry ground to 120 mesh. CCT varies with product form and surface finish
2304 25072205LDX 2101 ® LDX 2404 ™
CCT , ° C
50
40
30
20
10
0
4404 904L4307 4436 254 SMO ®
tothedropevaporationmethod.Thismeansthatasaltsolu-tionisallowedtoslowlydripontoaheatedspecimen,whileitisbeingsubjectedtotensilestress. Bythismethodthethresholdvalueisdeterminedfortheminimumstressforfailureafter500hourstestingat80-120°C.Thethresholdvalueisusuallyexpressedasaper-centageoftheproofstrengthofthesteelat200°C.Figure7showstheresultsofsuchatest.Itisevidentthatduplexste-elsaresuperiortoconventionalausteniticstainlesssteel,suchas4307and4404.
6
100
80
70
90
60
50
40
30
20
10
0
4404
2304 2205
904L
2507 4307
<10<15
254SMO®
LDX2101®
LDX2404™
Min
imu
m s
tres
s fo
r fa
ilure
, % o
f R
at 2
00°C
p0.
2
Fig. 7. Typical threshold stresses determined using the drop evaporation test.
Duplex Stainless Steel
Sulphide induced stress corrosion cracking
Inthepresenceofhydrogensulphideandchloridestheriskofstresscorrosioncracking,atlowtemperatures,increases.Suchenvironmentscanexist,forexample,inboreholesforoilandgaswells.Duplexgrades,suchas2205and2507havedemonstratedgoodresistance,while13%chromiumsteelshaveshownatendencytowardsstresscorrosioncrack-ing.However,cautionshouldbeobservedregardingcondi-tionswithhighpartialpressureofhydrogensulphideandwherethesteelissubjectedtohighinternalstress. 2205and2507arebothapprovedmaterialsaccordingtoNACE MR0175 / ISO 1515 Petroleum and natural gas industries - Materials for use in H2S-containing environments in oil and gas production.Corrosion fatigue
Thecombinationofhighmechanicalstrengthandverygoodresistancetocorrosiongivesduplexsteelsahighcorrosionfatiguestrength.S-Ncurvesfor2205and4404insynthe-ticseawaterareshowninFigure8.Thecorrosionfatiguestrengthof2205isconsiderablyhigherthanthatof4404.
Intergranular corrosion
Duetotheduplexmicrostructureandlowcarboncontent,theduplexsteelshaveverygoodresistancetointergranularcorrosion.Thecompositionofthesteelensuresthatauste-niteisreformedintheheat-affectedzoneafterwelding.Theriskofundesirableprecipitationofcarbidesandnitridesinthegrainboundariesisthusminimised.
Erosion corrosion
Stainlesssteelingeneraloffersgoodresistancetoerosioncorrosion.Duplexgradesareespeciallygoodthankstotheircombinationofhighsurfacehardnessandgoodcorrosionresistance.Examplesofapplicationswherethisisbeneficialaresystemssubjectedtoparticlescausinghardweare.g.pipesystemscontainingwaterwithsandorsaltcrystals.
Galvanic Corrosion
Galvaniccorrosioncanoccurwhentwodissimilarmetalsareconnected.Thenoblestmaterialisprotectedwhilethelessnoblematerialismoreseverelyattacked.Aslongastheduplexstainlesssteelsarepassivetheyare,inmostenviron-ments,noblerthanothermetallicconstructionmaterials,meaningthatthestainlesssteelisprotectedwhilethecorro-sionrateofe.g.carbonsteelisincreased. Galvaniccorrosiondoesnotoccurbetweendifferentgradesofstainlesssteelsaslongasbothgradesarepassive.
Fig. 8. Corrosion fatigue of stainless steel in synthetic seawater. Rotating bending test, 1500 r/min, with smooth specimens from 15 mm plate.
Stress amplitude (S), MPa
Number of cycles to failure (N)
500
400
300
200
100
0 105 106 107
2205
4404
7
2304
4404
4301
1200
1000
800
600
400
200
0
R
R
m
p0.2
LDX 2101®
En
gin
eeri
ng
str
ess
(MP
a)
Engineering Plastic Strain (%)0 20 40 60
2507
2205
904L
1200
1000
800
600
400
200
0
LDX 2404™
En
gin
eeri
ng
str
ess
(MP
a)
Engineering Plastic Strain (%)0 20 40 60
254SMO®
14
12
1
0.8
0.6
0.4
0.2
0
r-va
lue
Angle to rolling direction0 45 90
2205
2507
904L
254SMO
™
®
LDX 2404
14
12
1
0.8
0.6
0.4
0.2
0
r-va
lue
Angle to rolling direction0 45 90
®LDX 2101
2304
4301
4404
Duplex Stainless Steel
Fig. 10. Stress-strain curves for duplex and austenitic grades with corresponding corrosion resistance.
Fig. 9. Stress-strain curves for duplex and austenitic grades with corresponding corrosion resistance.
Fig. 11. r-values for duplex and austenitic grades with corresponding corrosion resistance.
Fig. 12. r-values for duplex and austenitic grades with corresponding corrosion resistance.
Fabrication
Duplexstainlesssteelissuitableforallformingprocessesavai-lableforstainlesssteel.Thehighproofstrengthcomparedtoausteniticandferriticsstainlesssteelcanimposesomedifferen-cesinformingbehaviourdependingonchosenformingtechni-que,suchasanincreasedtendencytospringback.Thispointisparticularlyrelevanttoformingofanyhighstrengthsteel.Iftheformingprocessisnotalreadydecided,itiscertainlypossibletochoosethemostsuitableoneforduplexgrades.Moreover,anexcellentinterplaybetweenhighproofstrength,workhardeningrateandelongationpromotetheduplexgradesforlightweightandcost-efficientapplicationswithcomplexshapes. Theimpactofthehighstrengthvariesfordifferentformingtechniques.Commonforallisthattheestimatedformingforceswillbehigherthanthecorrespondingausteniticandfer-riticstainlesssteelgrades.Thiseffectwillusuallybelowerthanexpectedfromjusttheincreaseinstrengthsincethechoiceofduplexstainlesssteelisoftenassociatedwithdowngauging.Itisimportanttoconsiderthatduplexstainlesssteelmayalsobemoredemandingforthetoolmaterialsandthelubricant.Alsointhiscaseattentionshouldbegiventothedowngauging. Outokumpu,AvestaResearchCentre,cansupportcustomersindetailedcomputeranalysesoftheimpactontheformingpro-cesswhenstainlesssteelgradesaretobeselected.Cold forming
Thehighstrengthoftheduplexgradesisclearlydemonstratedwhenthestress-straincurvesofOutokumpuduplexgradesarecomparedwiththecorrespondingausteniticgrades,seeFigures9-10.TheRp0.2/Rmratioalsodemonstratesalowerdeformationhardeningrateforduplexgradesathighervaluesoftheplasticstrain. Asheetmaterial'sabilitytowithstandthinningduringfor-mingisdemonstratedbyther-value,anisotropicvalue,indiffe-renttensiledirections,andthehigherther-valuethebetter,seeFigures11-12.
8 Duplex Stainless Steel
Heat treatment
TemperaturessuitableforheattreatmentarepresentedinTable8.Theheattreatmentshouldbefollowedbysubse-quentrapidcoolinginwaterorair.Thistreatmentappliesforbothsolutionannealingandstressrelieving.Thelat-tercaninspecialcasesbedoneat500-550°C.FurtherinformationconcerningtheseoperationsisavailablefromOutokumpu. Fig. 14. Machinability index for duplex and some
other stainless steels.
LDX 2101® 2304 LDX 2404™ 2205 2507
Hot forming 1100-900 1100-900 1120-900 1150-950 1200-1025
Quench annealing 1020-1080 950-1050 1000-1120 1020-1100 1040-1120
Stress relief annealing 1020-1080 950-1050 1000-1120 1020-1100 1040-1120
Characteristic temperatures, °C Table8
See also ”Welding”
Machining
Duplexsteelsaregenerallymoredemandingtomachinethanconventionalausteniticstainlesssteelsuchas4404,duetothehigherhardness.HoweverLDX2101®hasshownexcel-lentmachiningproperties. Themachinabilitycanbeillustratedbyamachinabilityindex,asillustratedinFigure14.Thisindex,whichincreaseswithimprovedmachinability,isbasedonacombinationoftestdatafromseveraldifferentmachiningoperations.Itprovidesagooddescriptionofmachinabilityinrelationto4404.ForfurtherinformationcontactOutokumpu.
4404 LDX 2101® LDX 2404™ 2304 2205 2507
Relative machinability
1.5
1
0.5
0
Theformabilityofduplexstainlesssteelcanbecharacteri-zedinseveralways.Figure13showsarelativerankingofOutokumpuduplexgradesincomparisontoaselectionofausteniticgrades.Therankingresemblesthemostcriticalfailuremodeinsheetforming. Inpuredrawing,theduplexgradesarecomparabletoaus-teniticgradesinthataboutthesamelimitingdrawingratiocanbedrawn.
Hot forming
HotformingisperformedatthetemperaturesillustratedinTable8.Itshould,however,beobservedthatthestrengthoftheduplexmaterialsislowathightemperaturesandcom-ponentsrequiresupportduringfabrication.Hotformingshouldnormallybefollowedbyquenchannealing.
1.0
0.8
0.7
0.9
0.6
0.5
0.4
0.3
0.2
0.1
0.0
44042304 2205 904L2507 4301LDX 2101® 254 SMO®LDX 2404™
Form
abili
ty in
pla
ne
stra
in
Fig 13. Formability ranking of some duplex and austenitic grades in relation to grade 4301.
9Duplex Stainless Steel
Welding
Duplexsteelsgenerallyhavegoodweldabilityandcanbeweldedusingmostoftheweldingmethodsusedforausteni-ticstainlesssteel:• Shieldedmetalarcwelding(SMAW)• GastungstenarcweldingTIG(GTAW)• GasmetalarcweldingMIG(GMAW)• Flux-coredarcwelding(FCW)• Plasmaarcwelding(PAW)• Submergedarcwelding(SAW)• Laserwelding• Resistancewelding• Highfrequencewelding
Duetothebalancedcomposition,theheat-affectedzoneobtainsasufficientlyhighcontentofaustenitetomaintainagoodresistancetolocalisedcorrosion.Theindividualduplexsteelshaveslightlydifferentweldingcharacteristics.Formoredetailedinformationregardingtheweldingofindividualgrades,seetheOutokumpuWeldingHandbookorcontactOutokumpu.Thefollowinggeneralinstructionsshouldbefollowed:• Thematerialshouldbeweldedwithoutpreheating.• Thematerialshouldbeallowedtocoolbetween
passes,preferablytobelow150°C.• Toobtaingoodweldmetalpropertiesinaswelded condition,fillermaterialshallbeused.ForLDX2101®reasonablygoodpropertiescanbeobtainedalsowithout
filler.
Steel grade Consumable Typical composition, % by wt. ISO C Cr Ni Mo N Designation
LDX 2101® 23 7 NL 0.02 23.5 8.0 0.3 0.14
22 9 3 NL 0.02 22.5 8.5 3.0 0.15
2304 23 7 NL 0.02 23.5 8.0 0.3 0.14
22 9 3 NL 0.02 22.5 8.5 3.0 0.15
LDX 2404™ 22 9 3 NL 0.02 22.5 8.5 3.0 0.15
2205 22 9 3 NL 0.02 22.5 8.5 3.0 0.15
2507 25 9 4 NL 0.02 25 9.5 3.5 0.25
• Therecommendedarcenergyshouldbekeptwithincer-tainlimitstoachieveagoodbalancebetweenferriteandausteniteintheweld.Theheatinputshouldbeadaptedtothesteelgradeandbeadjustedinproportiontothethicknessofthematerialtobewelded.
• Post-weldannealingafterweldingwithfillerisnotnecessary.Incaseswhereheattreatmentisconsidered,e.g.,forstressrelieving,itshouldbecarriedoutinaccordancewiththetemperaturesstatedinTable8,butwiththeminimumtemperatureincreasedwith30-50°Ctosecurefulldissolutionofintermetallicphaseinthetheweldmetal.
• ToensureoptimumpittingresistancewhenusingGTAWandPAWmethods,anadditionofnitrogenintheshielding/purginggasisrecommended.
Post fabrication treatment
Inordertorestorethestainlesssteelsurfaceandachievegoodcorrosionresistanceafterfabrication,itisoftenneces-sarytoperformapostfabricationtreatment. Therearedifferentmethodsavailable,bothmechanicalmethodssuchasbrushing,blastingandgrindingandchemi-calmethods,e.g.pickling.Whichmethodtoapplydependonwhatconsequencesthefabricationcaused,i.e.whattypeofimperfectionstoberemoved,butalsoonrequirementswithregardtocorrosionresistance,hygienicdemandsandaestheticappearance.Formoreinformation,seetheOutokumpuWeldingHandbook.
Welding consumables Table9
10 Duplex Stainless Steel
Hot rolled plate, sheet and strip
Cold rolled sheet and strip
Bars and forging
Tube, Pipe and Fittings
Products Table10
EN 10028-7 Flat products for pressure purposes – Stainless steels
EN 10088-2 Stainless steels – Corrosion resisting sheet/plate/strip for general and construction purposes
EN 10088-3 Stainless steels – Corrosion resisting semi-finished products/bars/rods/wire/sections for general and construction purposes
EN 10088-4 Stainless steel flat products, technical delivery conditions, steels for construction
EN 10088-5 Stainless steel long products, technical delivery conditions, steels for construction
EN 10217-7 Welded steel tubes for pressure purposes – Stainless steel tubes
EN 10272 Stainless steel bars for pressure purposes
EN 10296-2 Welded circular steel tubes for mechanical and general engineering purposes - Stanless Steel tubes
ASTM A182 / ASME SA-182 Forged or rolled alloy-steel pipe flanges, forged fittings etc for high temperature service
ASTM A240 / ASME SA-240 Heat-resisting Cr and Cr-Ni stainless steel plate/sheet/strip for pressure purposes
ASTM A276 Stainless and heat-resisting steel bars/shapes
ASTM A479 / ASME SA-479 Stainless steel bars for boilers and other pressure vessels
ASTM A789 / ASME SA-789 Seamless and welded duplex stainless steel tubing for general purposes
ASTM A790 / ASME SA-790 Seamless and welded duplex stainless steel pipe
ASTM A815 / ASME SA-815 Wrought ferritic, duplex, martensitic stainless steel piping fittings
ASTM A928 Duplex stainless steel pipe welded with addition of filler metal
VdTÜV WB 418 Ferritisch-austenitischer Walz- und Schmiedestahl, 1.4462
VdTÜV WB 496 Ferritisch-austenitischer Walz- und Schmiedestahl, 1.4362
VdTÜV WB 556 Austenitic-ferritic steel X2CrMnNi21-5-1, Material No. 1.4162, Manufacturer designation: LDX 2101®
NACE MR0175 / ISO 1515 Petroleum and natural gas industries - Materials for use in H2S-containing environments in oil and gas production.
Norsok M-CR 630, MDS D45, MDS D55
ASME Boiler and Pressure 21Cr-5Mn-1.5Ni-Cu-N (UNS S32101), Austenitic-Ferritic Duplex Stainless SteelVessel Code Case 2418 Section VIII, Division 1
Material Standards Table11
Outokumpu 2205 corresponds in American Standards to two different steel designations; UNS S31803 and UNS S32205. The latter has closer tolerance limits for some alloying elements to further optimise properties such ascorrosion resistance and strength, the properties described in this datasheet corresponds to UNS S32205.
See www.outokumpu.com/prodprog
11Duplex Stainless Steel
Information given in this brochure may be subject to alterations without notice. Care has been taken to ensure that the contents of this publication are accurate but Outokumpu and its affiliated companies do not accept responsibility for errors or for information which is found to be misleading. Suggestions for or descriptions of the end use or application of products or methods of working are for information only and Outokumpu and its affiliated companies accept no liability in respect thereof. Before using products supplied or manufactured by the company the customer should satisfy himself of their suitability.
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www.outokumpu.com
Outokumpu Stainless AB,Avesta Research Centre
Box 74, SE-774 22 Avesta, Sweden
Tel. +46 (0)226 810 00, Fax +46 (0)226 810 77
research.stainless@outokumpu.com
Outokumpu is a global leader in stainless steel. Our vision is to be the undisputed number one in stainless, with success based on operational exellence. Customers in a wide range of industries use our stainless steel and services worldwide. Being fully recyclable, maintance-free, as well as very strong and durable material, stainless steel is one of the key building blocks for sustainable future. What makes Outokumpu special is total customer focus, all the way, from R&D to delivery. You have the idea. We offer world-class stainless steel, technical know-how and support. We activate your ideas. (www.outokumpu.com)
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