CORTENAandCORTENBareweatherresistantsteelgradesoptimisedthroughtheiralloyingelements(copper,chromium,nickelandphosphorus)foravarietyofenvironmentsandpurposes.Whenthetotalcostsoverthelifecycleofstructuresaretakenintoaccount,significanteconomicbenefitsresultfromusingtheseweatheringsteels.Deliveredasheavyplates,cutlengths,slitstripsandcoils,thisproductrangeisproducedunderlicencefromtheUnitedStatesSteelCorporation.CorTenisaregisteredtrademarkofUSXCorporation.Applications:l Chimneysl Bridgesl Tubularbridgesl Faadesl Containersl Tanks

ProductshapesHeavyplates.Cutlengths,slitstripsandcoils.Cutlengthswithmilledges.Maximumwidthofeachsteelgradedependsonthethicknessofthecutlength.Heavyplates.Maximumlengthofeachsteelgradedependsonthethickness.ThethicknessrangesforheavyplatesandcutlengthsmanufacturedfromweatheringsteelgradesasperEN100255arethesameasthoseoftheapproximatelyequivalentCORTENgrades.SteelgradesandtheirapproximatecorrespondenceforweatherresistanceForexactcomparisons,originaldatasheetsandstandardsmustbeused.TheyieldstrengthisguaranteedasReLforCORTENsteelsandasReHfortheEN100255:2004weatheringsteelgrades.ACharpyVimpacttestiscarriedoutonstandardsteelsequivalenttoCORTENB.Moredetailedinformationondimensionsisprovidedinthefollowingtechnicalbrochures:llSteelgrade Thicknessmm Widthmm LengthmCORTENA 212 10001860 212CORTENB 215 10001860 212Steelgrade Thicknessmm Widthmm LengthmCORTENA 612 19013300 215CORTENB 640 19013300 215Steelgrade EN100255:2004CORTENA S355J0WPCORTENB S355J0WandS355J2W

Plateproducts:EN10029ClassAStripproducts:EN10051 Plateproducts:EN101632ClassA3Heavyplatesaredeliveredinasrolledcondition.Cutlengths,slitstripsandcoilsaredeliveredinasrolledconditionorinpickledcondition.

Theanticorrosivepropertiesofweatherresistantsteelsarebetterthanthoseofotherstructuralsteelsinmanyapplications.Theenhancedweatherresistanceisbasedontheoxidelayer,i.e.patina.Theuseofuncoatedweatherresistantsteelinsteelstructuressavessurfacetreatmentcosts.Theelegantlybrownpatinatedsurfaceisarchitecturallydistinguished.ThepatinatypesurfacecanbeobtainedinweatherresistantsteelsusingtheRustBrownmethod,whichextendsthescopeofapplicationofweatherresistantsteelstoindoorstructures.Weatherresistantsteelinfluegasstructuresprolongstheservicelifeofchimneysandfluegasducts.MaterialstestingAninspectionlotofCORTENsteelgradesatthesteelworksconsistsofamaximumof40tonnesofplatesorcoilsfromthesamecast.Oneseriesoftestsperinspectionlotshallbecarriedout:atensiletestwithtransversalsamplesand,ifrequired,aCharpyVimpacttestwithlongitudinalsamples.InspectionandsamplingofsteelgradesasperEN100255:2004shallbecarriedoutincompliancewiththestandard.MechanicalpropertiesIfagreeduponseparately,CORTENBcanbedeliveredwithaguaranteedlongitudinalimpactstrengthof27Jatthetemperatureof20C,inwhichcaseitismarkedwithCORTENBD.CORTENEN100255:2004ChemicalcompositionThechemicalcompositionofweatheringsteelsasperEN100255complieswiththestandard.CarbonequivalentCEVCEV=C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15CarbonequivalentsforgradesasperEN100255areinlinewiththestandard.YieldstrengthReLN/mm2MinimumTensilestrengthRmN/mm2MinimumElongationA50%MinimumCORTENA 345 485 20CORTENB 345 485 19YieldstrengthReHN/mm2MinimumThicknessmmTensilestrengthRmN/mm2MinimumThicknessmmElongationA80%MinimumThicknessmmA5MinimumThicknessmm 216 (16)40 2(3) 340 2 (2)2.5 (2.5)(3) 340S355J0WP 355 510680 470630 14 15 16 20S355J0W 355 345 510680 470630 14 15 16 20S355J2W 355 345 510680 470630 14 15 16 20 Content,%(ladleanalysis)CMaximum Si Mn PSMaximumAl V Cu CrNiMaximumCORTENA0.12 0.250.750.200.500.070.150.030 0.0150.06 0.250.550.501.250.65CORTENB0.19 0.300.650.801.250.035max. 0.030 0.0200.060.020.100.250.400.400.650.40 Thicknessmm CEVtypical ProductCORTENA 212 0.35 StripproductsCORTENA 612 0.39 PlateproductsCORTENB 215 0.38 StripproductsCORTENB 620 0.48 PlateproductsCORTENB (20)40 0.50 Plateproducts

TheadvantagesofpatinaindifferentconditionsThankstotheirpatinalayer,weatheringsteelscanbeusedinoutdoorstructureswithoutanyseparatesurfacetreatment.Atitsbest,weatheringsteelcansavethecostsofallthesurfacetreatmentandtherepairsnecessarylater.Thecostadvantageincomparisontopaintedstructuresisemphasisedinenvironmentswhereregularrepaintingisrequired.TheRustBrownmethodextendsthearchitecturaluseofweatheringsteelsinindoorstructures.Itisrecommendedtomakeallmarkingsinallapplicationsduringconstructionusingchalkorwatersolublecolours.OpenairstructuresandpatinaWeatherresistanceisbasedontheoxidelayer,i.e.patina,whichformsonthesurfaceofthesteel,andwhich,asaresultofthealloyingelements,isdenseandnearlyimpervioustooxygen.Undernormalweatherconditionsthepatinawillforminabout1836months,ifthesurfaceisalternatelywetanddry.Atfirst,thepatinaisareddishbrowncolour,butwithtimetakesonadarkerhue.Inindustrialenvironments,thepatinaformsmorequicklyandisdarkerincolourthaninruralareas.Inmarineenvironments,theformationoftheprotectivepatinamaybeslowerduetochlorideexposure.Foropenairstructures,theslowcorrosionrateistakenintoaccountbyaddingcorrosionallowancetothenominalthickness.ExampleofcorrosionallowanceforuntreatedCORTENBsteel1)Withthechiefimpurityintheairbeingsulphurdioxide,SO2.2)InadditiontoSO2theairalsocontainschloride.Alsoforlocationsintheimmediatevicinityofsaltwater.Inordertoensuretheuniformcolourofthepatina,allimpuritiesmustbecleanedfromthesteelsurface.Organicimpuritiessuchasoilorprotectivegreasesmustberemovedbywashing.Surfaceoxidation,oxidesorrustcanberemovedbyeithershotblastingorpickling.Thiswillalsoacceleratethepatinaformationprocess.Thesurfaceofcleanweatheringsteelcanbeprepatinatedbyallowingthesurfacetogetwetanddryortousesuitableacidsolutions.IndoorstructuresThepatinaformedonstructuralpartswhicharenotdirectlyexposedtoweatherwillnotbeasuniformasthatonpartswhicharealternatelymadewetanddried.Smallvariationsincolourmayalsooccuronpartswhicharesubjectedtostronglocalvariationintemperature.Anexampleofthisisawallblockundereaves.TheRustBrownmethodhasbeendevelopedforindoorstructures.Itproducesaninstantpatinatypelayeronthesurfaceoftheweatherresistantsteel.Themethodiseasytouse.SteelsurfacesmustbecleanedbeforetheRustBrowntreatmentandfinallythepatinalayerisfixedonthesurfacewithavarnish.FurtherinformationisavailablefromourCustomerService.SubmergedstructuresSteelsurfaceswhicharecontinuallywetdonotformaprotectivelayer.Thesemaybe,forexample,thesurfacesofstructureswhichareincontactwiththegroundorsubmergedinwater.Inthesecases,itisrecommendedtopainttheweatheringsteelsurface.ExposuretowastegasesandhightemperatureconditionsWeatheringsteelsresistthecorrosiveeffectofsulphurcontainingstackgasesverywell,evenbetterthanstainlesssteel.Weatheringsteelsareattheirbestinconstruction,andaremainlyusedattemperaturesabovethedewpointofsulphuricacidbutareoccasionallycooleddowntotemperaturesbelowthedewpoint.Theseconditionsprevailinmanywastegasstructureswhichcooldownbelowthedewpointduringshutdowns.Thelifeexpectancyoftheweatheringsteelisextendedunderconditionsofalternatewettinganddrying.Attemperaturesconstantlybelowthedewpointanexcessiveamountofacidiscondensedonthesteelsurface,whichmaybedetrimentaltotheresistancetocorrosion.Thespecialalloyingofthesteel,especiallywithchromium,improvesinadditionscalingresistanceathightemperatures,evenuptoashighas600650C.However,whenusingweatheringsteelsattemperaturesover425C,boththecreepresistancerequirementsand,inphosphorusalloyedsteel,possiblethermalembrittlementofthematerialmustalsobetakenintoaccount.PaintedstructuresThesurfaceofweatheringsteelcanbepaintedusingthesamemethodsappliedinpaintingordinarysteels.Asaresultofthespecialalloyingofthesteel,acoatofpaintcanlasttwiceaslongasacoatingonordinarysteel.Ifweatheringsteeliscontinuouslyexposedtowater,itisusuallyalwaysrecommendedtobepainted.TypeofatmosphereCorrosionallowancetobeaddedforonesideofthenominalthicknessforeach10yearperiodofworkinglife First10yearperiodmm Eachfollowing10yearperiodmmRural 0.10 0.05Urban1)0.20 0.05Industrial2)0.20 0.10

Therangeofprefabricationsavailableincludesbending,shapecutting,precisioncuttingandbevelling.CuttingWideflatsfromplateandstripthatarereadyforassemblyanddimensionallyaccuratespeedupthemanufactureofsteelstructuresandassembly,andavoidwastingmaterial.Thankstotheextensiverangeavailable,steelgradesbestsuitedfortheapplicationinquestioncanbeused.Manufactureandthethroughputtimeofinstallationwilldecreaseusingflatcutshapes.Thecustomerwillreceivetheneededcomponentsreadyforinstallation,andcanthusavoidunnecessarymaterialandstoringcosts.Ifordered,theproductsaredeliveredasshopprimed,bevelledandbent.BevellingPrecisioncutlengthsandprecisioncutplateswithabevellededgearecomponentsthatcanbedelivereddirectlytotheinstallationsite,whichsavestimeandreducestransportandstoragecosts.Thedimensionallyaccurategrooveensuresuninterruptedautomatedweldingandfitting.BentplateproductsBentplateproductsarecomponentsthatarereadytobedeliveredtotheinstallationsite,whichisbeneficialintermsofscheduleaswellastransportandstoringcosts.Ifneeded,theproductscanalsobeorderedasshopprimed,furnishedwithweldingbevels,andcuttoshape.Premarkedmatchmarksfacilitateinstallation. WeldingWeatheringsteelscanbeweldedunderworkshopconditionsusingallthecommonweldingprocesses.Lowhydrogenweldingproceduresandconsumablesarerecommended.Beforewelding,thepatinamustberemoved,downtothebaresteel,fromthesteelsurfaceoverabandofapproximately1020mmwidealongtheweldedjoint.Itisalsoequallyimportanttoremoveanymoisture,grease,oilandotherimpuritiesfromthesurface.WorkingtemperatureThecarbonequivalentvaluesareslightlyhigherinweatheringsteelthaninS355structuralsteel,whichincreasesthepreheatingneedcorrespondingly.InpracticethisdifferenceappliesonlytoCORTENBandthecorrespondingsteelsbecause,thankstotheirlowermaterialthickness,steelgradesalloyedwithphosphorusdonotusuallyrequireanelevatedworkingtemperature.Whenweldingthosesteels,itisrecommendedthatforplatesofover15mmthicknesstheworkingtemperatureshouldbeincreasedto100200C.Inmultipassweldingthetemperaturebetweendifferentpassesmustnotexceed200Cinorderthatthetoughnessoftheheataffectedzone(HAZ)remainsgood.Choiceofweldingconsumablesl Theweatherresistanceofweldedjointscanbeensuredbyusingfillermaterialscorrespondingtothealloyingofthebasematerial.l Themechanicalpropertiesoftheweldedjointhavetobeatleastequivalenttothoseofthebasematerial.Unnecessaryoverstrengthistobeavoidedasanincreaseinstrengthalsoincreasesresidualstress.l Theimpactstrengthoftheweldedjointmustmeetthesetrequirements,whichareusuallythesameasthose.l Ifthebaseandfillermaterialsmixsufficientlytoprovidegoodweatheringresistance,ordinarynonalloyedconsumablescanbeused.Sufficientmixingisachievedinsinglerunweldingofunder4mmplatesforbuttjoints,andforfilletweldswithadesignthroatthicknessofuptoapproximately4mm.l Generallythereisasmallcolourdifferencebetweenanonalloyedconsumablematerialusedinaweldandtheweatheringsteelbasematerial.l Inthemultirunweldingofthickplatesatleastthefinalrunsshouldbemadeusingweatheringconsumablesiftheweldmetalisalsointendedtobeweatherresistant.l Weldingconsumablesofsufficientdeformationcapacitymustbeusedforthesealingandrootruns.l Lowhydrogenconsumablesmustbeused,storedanddriedinaccordancewiththemanufacturersinstructions.

FormingWeatheringsteelscanbecoldformedinthesamemannerasS355structuralsteels.Thetable[table6]showsthesmallestallowablebendingradiitobeusedforflanging.Successfulformingrequiresgoodworkshoptechnologyfromtheproducerofthesteelproduct.Worntools,insufficientlubrication,surfacedefectsonplates,andcuttingburrsmayallreducethequality.Shotblastingmayalsobeunfavourable.Platesstoredoutsideundercoldconditionsmustbetakeninsidetowarmupsufficientlybeforebeingformed.TheformabilityofEN100255:2004weatheringsteelsisinaccordancethestandard.Valuesapplytoallformingdirections.HeattreatmentWeatheringsteelapplicationsdonotnormallyrequirepostweldheattreatment.If,however,thisisrequiredbythecustomerortheauthorities,itisrecommendedthatstressrelievingornormalisingiscarriedoutinaccordancewiththetablebelow.CuttingWeatheringsteelscanbecutthermallyandmechanicallyinalmostthesamemannerastheS355structuralsteels.Whenflamecuttingthickplates,theworkingtemperaturerecommendationsconcerningweldingcanbeusedasaguideline.DuetothinplatethicknessCORTENAandcorrespondingsteelsdonotnormallyneedanelevatedworkingtemperatureforthermalcutting.Slowingdownthecuttingspeedandincreasingtheworkingtemperaturehaveasimilareffectoncutting:thecoolingrateofthecuttingpointdecreasesandsodoestheriskofthermalcracks.Whenhandlingweatheringsteels,itshouldberememberedthataplatetakendirectlyfromcoldoutsidestorageneedsadequatetimetowarmupbeforemechanicalcutting. Thicknessmm (2)3 (3)4 (4)5 (5)6 (6)7 (7)8 (8)10 (10)12 (12)14 (14)16 (16)18 1820 SmallestallowableinternalbendingradiusmmCORTENA 6 8 10 12 21 24 30 36 42 CORTENB 6 8 10 12 21 24 30 36 42 48 54 60Heattreatment TemperatureCTreatmenttimeMannerofcoolingStressrelieving 550600(target580)2minutes/millimetrethickness,minimum30minutes.Slowcoolinginthefurnace.Normalising 860940(target910)1minute/millimetrethickness,minimum15minutes.Freecoolinginairatmosphereoutsidetheoven.

DeliveryconditionsHeavyplates:Hotrolled,normalisedrolledornormalisedinfurnace.Cutlengths,slitstripsandcoils:Controlledrolledorthermomechanicalrolled.InspectiondocumentsTheinspectiondocumentshallbespecifiedatthetimeoforder.TheEuropeantypesofinspectiondocumentsaredefinedintheEN10204:2004standard.GeneraldeliveryinformationforhotrolledsteelsGeneraldeliveryinformationforhotrolledsteelscanbefoundfromdocumentsMarkingsandpacking,UltrasonictestingandGeneraltermsofsale.