发布时间 : 星期二 文章ASTM A262 2015 奥氏体不锈钢晶间腐蚀敏感性检测标准方法 - 图文更新完毕开始阅读
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TABLE2UseofEtchStructureClassi?cationfromOxalicAcid
EtchTestwithNitricAcidTestAGradeAISI304AISI304LACICF-8ACICF-3
AAcceptableEtchStructures
Step,dual,endgrainStep,dual,endgrainStep,dual,isolatedferriteStep,dual,isolatedferrite
II
poolspools
SuspectEtchStructuresBDitch,endgrainIIDitch,endgrainII
Ditch,interdendriticditchesDitch,interdendriticditches
30.3Heater—Ameansforheatingthetestsolutionsandofkeepingthemboilingthroughoutthetestperiod.Anelectricallyheatedhotplateissatisfactoryforthispurpose.
30.4Balance—Ananalyticalbalancecapableofweighingtoatleastthenearest0.001g.
30.5Desiccator—Forstorageofpreparedspecimenspriortotesting.
31.NitricAcidTestSolution
31.1Thetestsolutionshallbe65.060.2weight%asnitricaciddeterminedbyanalysis.
31.2Preparethissolutionbyaddingreagentgradenitricacid(HNO3Table3)toreagentwaterattherateof108mLofreagentwaterperlitreofreagentnitricacid.
31.3(Warning—Protecttheeyesanduserubberglovesforhandlingacid.Placethetest?askunderahood.)
31.4ThenitricacidusedshallconformtotheAmericanChemicalSocietySpeci?cationsforReagentChemicalsandtheadditionalrequirementsofthistestmethodasshowninTable3.32.Sampling
32.1Obtainandprepareonlybasemetalsamples.
32.1.1Therearetwoclassesofspecimenstobeconsidered:basemetal,andprocess-affectedmetal.Process-affectedmetalcontainsanyconditionthataffectsthecorrosionpropertiesofthematerialinanon-uniformway,suchas(butnotlimitedto)welds;carburized.nitrided,oroxidizedsurfaces;mechanicaldeformation;andareasaffectedbyheat.Basemetalhasnoneoftheseconditions.
32.1.2ThePracticeCtestinvolvesimmersingtheentirespecimenandaveragingthemasslossovertheentiresurfaceofthespecimen.Welding,carburization,mechanicaldeformation,andthelike,affectonlypartofaspecimen.
32.1.3Themasslossratefromprocess-affectedmetalisexpectedtodifferfromthatfrombasemetal;thepresenceofprocess-affectedmetalinaspecimenwillaffectthecalculatedtestresultinanunpredictableway.
32.1.4Ifthepresenceoftheseorotherlocalizedconditionsisaconcerntothepurchaser,thenteststhatdonotaveragethemasslossoverthetotalspecimensurfacearea,suchasPracticeA,theOxalicAcidEtchTest,orPracticeE,theCopper–CopperSulfate–SulfuricAcidTestforDetectingSusceptibilityto
TABLE3NitricAcidCompositionLimits
Minimum
NitricAcid(HNO3),masspercentAsh,ppm
ChlorideasCl,ppmSulfate,as(SO4),ppmArsenic(As),ppmHeavymetals,asPb,ppm
Iron,(Fe),ppm
AdditionallimitsperPracticesA262Fluorine(F),ppm
Phosphate(PO4),ppm
69.0{{{{{{
Maximum71.050.510.010.20.2
GradesnotlistedinthistableeitherhavenotbeenevaluatedforuseofPracticeAwithPracticeBorhavebeenfoundtogiveacceptableresultsintheetchtestwhilegivingunacceptableresultsinPracticeB.InthelattercasePracticeAwouldpassmaterialthatshouldhavebeensubjectedtotheferricsulfate-sulfuricacidtest.BSpecimenshavingthesestructuresshallbetestedinthenitricacidtest.
givenarapidscreeningtestinaccordancewithproceduresgiveninPracticeA,OxalicAcidEtchTestforClassi?cationofEtchStructuresofAusteniticStainlessSteels.Theuseoftheetchstructureevaluationsinconnectionwiththenitricacidtestisspeci?edinTable2.
29.2Heattreatthematerialinaccordancewith33.1priortoperformingtheetchtest.
29.3Ignore“process-affected”areas,ifany(seeSection32);applicationofthenitricacidtesttoprocess-affectedareasiscurrentlyoutsidethescopeofPracticeC.
29.4Corrosiontestspecimenshavingacceptableetchstruc-turesintheOxalicAcidEtchTestwillbeessentiallyfreeofintergranularattackinthenitricacidtest;suchspecimensareacceptablewithouttestinginthenitricacidtest.Allspecimenshavingsuspectetchstructuresshallbetestedinthenitricacidtest.
30.Apparatus
30.1Container—A1-LErlenmeyer?askequippedwithacold?nger-typecondenser,asillustratedinFig.9.
30.2SpecimenSupports—Glasshooks,stirrups,orcradlesforsupportingthespecimensinthe?askfullyimmersedatalltimesduringthetestandsodesignedthatspecimenstestedinthesamecontainerdonotcomeincontactwitheachother.
{{10.2
FIG.9FlaskandCondenserforNitricAcidTest
9
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IntergranularAttackinAusteniticStainlessSteels,shouldbelossofthespecimenduringtheearlypartofthetest.
considered.Detailsofthetestandacceptancecriteriashallbeasagreedbythepurchaserandproducer.
33.6Thestandardtestistotestonlyonespecimenofeachmaterialorlotofmaterial.However,incaseofdispute,theuse32.2Unlessotherwisespeci?edbythepurchaser,thepro-ofatleasttwospecimensforcheckpurposesisrecommended.ceduresforobtainingrepresentativebasemetalsamples,forremovingthespecimensfromthesamples,andthenumberof34.Procedure
specimensshallbeatthediscretionoftheproducer.34.1Useasufficientquantityofthenitricacidtestsolution32.3Whenspecimensarecutbyshearing,theshearededgestocover2thespecimensandtoprovideavolumeofatleast20shallbere?nishedbymachiningorgrindingpriortotesting.mL/cm(125mL/in.2)ofspecimensurface.Normally,avolumeofabout600mLisused.
33.PreparationofTestSpecimens
34.2Useaseparatecontainerforeachtestspecimen.
33.1Heattreatextra-lowcarbonandstabilizedgradesat34.2.1Asmanyasthreespecimensmaybetestedinthe650to675°C(1200to1250°F),whichistherangeofsamecontainerprovidedthattheyallareofthesamegradeandmaximumcarbideprecipitation,priortotesting.Thelengthofallshowsatisfactoryresistancetocorrosion.
timeofheating,andthemethodofsubsequentcoolingusedfor34.2.2Ifmorethanoneofthespecimenstestedinthesamethissensitizingtreatmenttogetherwiththecorrespondingcontainerfailtopassthetest,retestallthespecimensinmaximumpermissiblecorrosionrateshallbeasagreedbe-separatecontainers.
tweenthematerialproducerandpurchaser.
NOTE14—Excessivecorrosionofonespecimenmayresultinacceler-Natedcorrosionoftheotherspecimenstestedwithit.ExcessivecorrosionOTE11—Themostcommonlyusedsensitizingtreatmentis1hat675°C(1250°F).
mayoftenbedetectedbychangesinthecolorofthetestsolution,anditNmaybeappropriatetoprovideseparatecontainersforsuchspecimensOTE12—Thesizeandshapeofthespecimenmustbeconsideredwithrespecttoavailablefacilitiesforaccurateweighingandthevolumeoftestwithoutwaitinguntiltheendofthetestperiod.Arecordshouldbemadesolutiontobeused.Normally,themaximumconvenientweightofashowingwhichspecimensweretestedtogether.
specimenisabout100g.Inthecaseofbar,wire,andtubularproducts,the34.3Afterthespecimenshavebeenplacedintheacidintheproportionofthetotalarearepresentedbytheexposedcrosssectionmaycontainer,passcoolingwaterthroughthecondenser,bringthein?uencetheresults.Cross-sectionalareasintheseproductsmaybesubjecttoendgrainattackinnitricacid.Theproportionofendgrainintheacidtoaboilonthehotplate,andkeepboilingthroughoutthespecimenshouldthereforebekeptlowunlesssuchsurfaceisactuallytotestperiod(Note15).Aftereachtestperiod,rinsethespeci-beexposedinserviceinvolvingnitricacid.Inthislattercase,themenswithwaterandtreatbyscrubbingwithrubberoranylonproportionofendgraininthespecimenshouldbekepthigh.
brushunderrunningwatertoremoveanyadheringcorrosion33.2Wherefeasiblefortheproductform,grindalltheproducts,thendryandweighthem.Dryingmaybefacilitated,specimensurfacesusingCAMI/ANSI120[FEPA/ISOP120]ifdesired,bydippingthespecimensinacetoneaftertheyarepaper-backed,wetordry,closedcoatedabrasivepaper,withscrubbed.
waterasacoolant.Ifabrasivepaperisuseddry,polishslowly34.4(Warning—Ithasbeenreportedthatviolentboilingtoavoidoverheating.Donotuseabrasiveswithgrindingaids;resultinginacidspillscanoccur.Itisimportanttoensurethatsomegrindingaidscontain?uoridesthatcanaffectthetheconcentrationofaciddoesnotincreaseandthatanadequatemeasuredcorrosionrate.
numberofboilingchips(whichareresistanttoattackbythe33.3Removealltracesofoxidescaleandheattintformedtestsolution)arepresent.)
duringheattreatments.AnyscalethatcannotberemovedbyNOTE15—Takecaretopreventcontaminationofthetestingsolution,grinding(forexample,instampednumbers)mayberemovedespeciallyby?uorides,eitherbeforeorduringthetest.ExperiencehasbyusingoneofthepicklingsolutionsdescribedinPracticeshownthatthepresenceofevensmallamountsofhydro?uoricacidwillA380/A380M,TableA1.1.
increasethecorrosionrateinthenitricacidtest.Itisnotpermissible,forexample,toconductnitric-hydro?uoricacidtestsinthesamehoodwith33.4Measurethespecimen,includingtheinnersurfacesofnitricacidtests.
anyholestothenearest0.05mm(0.001in.),andcalculatethe34.5Thestandardtestconsistsof?veboilingperiodsoftotalexposedareaincm2.
48heachwithafreshtestsolutionbeingusedineachperiod.33.5Degreasethespecimenusingsuitablenonchlorinated34.5.1Acombinationofone48-hperiodandtwo96-hagents,suchassoapandlukewarmwater,oracetone(Note13).periods(notnecessarilyinthatorder)insteadof?ve48-htestDrythespecimensandweigheachonetothenearest0.001g.periodsmaybeusedifsoagreedbythepurchaser.Storethespecimensinadesiccatoruntilthetestistobeperformed.
35.CalculationandReport
N35.1Calculation—TheeffectoftheacidonthematerialOTE13—Thecleaningtreatmentdescribedmaybesupplementedbyimmersingthespecimeninnitricacid(forexample,20weight%at49toshallbemeasuredbydeterminingthelossofweightofthe60°C(120to140°F))for20min,followedbyrinsing,drying,andspecimenaftereachtestperiodandforthetotalofthetestweighing.Inthecaseofsmall-diametertubularspecimenswhichcannotperiods.UsingEq1,calculatethecorrosionrateforeachbeconvenientlyresurfacedontheinside,itisdesirabletoincludeinthespecimenforeachtestperiod,andforthetotalofthetestpreparationanimmersioninboilingnitricacid(65%)for2to4husingthesameapparatusasfortheactualtest.Thepurposeofthesetreatmentsperiods.
istoremoveanysurfacecontaminationthatmaynotbeaccomplishedby35.2Report—Reportthecalculatedcorrosionratesforthetheregularcleaningmethodandwhichmayincreasetheapparentweight
individualperiodsinchronologicalorder,aswellasthe
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averageforthe?vetestperiods.Ifthemodi?edtestperiods(34.5.1)areused,thenidentifyeachresultastothesequenceandlengthofthetestperiod.36.PrecisionandBias
36.1Precision—TheprecisionofPracticeCisbeingdeter-mined.
36.2Bias—Thispracticehasnobiasbecausetheresistancetointergranularcorrosionisde?nedonlyintermsofthispractice.
PRACTICEE—COPPER-COPPERSULFATE–16%
SULFURICACIDTESTFORDETECTINGSUSCEPTIBILITYTOINTERGRANULAR
ATTACKINAUSTENITICSTAINLESSSTEELS(4,5)37.Scope
37.1Thispracticedescribestheprocedurebywhichthecopper–coppersulfate–16%sulfuricacidtestisconductedtodeterminethesusceptibilityofausteniticstainlesssteelstointergranularattack.Thepresenceorabsenceofintergranularcorrosioninthistestisnotnecessarilyameasureoftheperformanceofthematerialinothercorrosivemedia.Thetestdoesnotprovideabasisforpredictingresistancetootherformsofcorrosion,suchasgeneralcorrosion,pitting,orstress-corrosioncracking.38.RapidScreeningTest
38.1Beforetestinginthecopper–coppersulfate–16%sul-furicacidtest,specimensofcertaingradesofstainlesssteel(seeTable4)maybegivenarapidscreeningtestinaccordancewiththeproceduresgiveninPracticeA(Sections4through13).Preparation,etching,andtheclassi?cationofetchstruc-turesaredescribedtherein.Theuseofetch-structureevalua-tionsinconnectionwiththecopper–coppersulfate–16%sulfuricacidtestisspeci?edinTable4.
38.1.1CorrosiontestspecimenshavingacceptableetchstructuresintheOxalicAcidEtchTestwillbeessentiallyfreeofintergranularattackinthecopper–coppersulfate–16%sulfuricacidtest.Suchspecimensareacceptablewithout
TABLE4UseofEtchStructureClassi?cationsfromtheOxalicAcidEtchTestwiththeCopper–CopperSulfate–16%Sulfuric
AcidTest
GradeAISIAISIAISIAISIAISIAISIAISIAISIAISIAISIAISIAISIAISI
Atestinginthecopper–coppersulfate–16%sulfuricacidtest.Allspecimenshavingsuspectetchstructuresmustbetestedinthecopper–coppersulfate–16%sulfuricacidtest.
38.1.2Heattreatthematerialwhenrequiredbyandinaccordancewith43.3.1priortoperformingtheetchtest.39.SummaryofPractice
39.1Asuitablesampleofanausteniticstainlesssteel,embeddedincoppershotorgrindings,isexposedtoboilingacidi?edcoppersulfatesolutionfor15h.Afterexposureintheboilingsolution,thespecimenisbent.Intergranularcrackingorcrazingisevidenceofsusceptibility.
39.2AlternativeTestingProcedures:
39.2.1Unlessprohibitedbythepurchaserinthepurchaseorder,thesupplierispermittedtomeettherequirementsofPracticeEbyperformingatestinaccordancewithISO3651–2,MethodA,providedthatthetestingperiodshallbeaminimumof15h.Whenasensitizationtreatmentisrequired,sensitizationheattreatmentT1[700°C610°C(1292°F618°F),30min,waterquench]shallbeusedunlessthesupplierandpurchasershallagreeuponpreparationofweldedtestpiecestobetestedintheas-weldedcondition.39.2.2Whenthisalternativetestprocedureisused,itshallbenotedonthetestreport.40.Apparatus
40.1ThebasicapparatusisdescribedinSection18.40.2SpecimenSupports—Anopenglasscradlecapableofsupportingthespecimensandcoppershotorgrindingsinthe?askisrecommended.
NOTE16—Itmaybenecessarytoembedlargespecimens,suchasfromheavybarstock,incoppershotonthebottomofthetest?ask.Acoppercradlemayalsobeused.
40.3HeatSource—Anygasorelectricallyheatedhotplatemaybeutilizedforheatingthetestsolutionandkeepingitboilingthroughoutthetestperiod.
41.Acidi?edCopperSulfateTestSolution
41.1Dissolve100gofreagentgradecoppersulfate(CuSO4·5H2O)in700mLofdistilledwater,add100mLofsulfuricacid(H2SO4,cp,spgr1.84),anddiluteto1000mLwithdistilledwater.
NOTE17—Thesolutionwillcontainapproximately6weight%ofanhydrousCuSO4and16weight%ofH2SO4.
AcceptableEtchStructuresStep,Step,Step,Step,Step,Step,Step,Step,Step,Step,Step,Step,Step,
dual,dual,dual,dual,dual,dual,dual,dual,dual,dual,dual,dual,dual,
endendendendendendendendendendendendend
graingraingraingraingraingraingraingraingraingraingraingraingrain
IIIIIIIIIIIIIandandandandandandandandandandandandand
IIIIIIIIIIIIIIIIIIIIIIIIII
SuspectEtchStructuresADitchDitchDitchDitchDitchDitchDitchDitchDitchDitchDitchDitchDitch
201202301304304L304H316316L316H317317L321347
42.CopperAddition
42.1Electrolyticgradecoppershotorgrindingsmaybeused.Shotispreferredforitseaseofhandlingbeforeandafterthetest.
42.2Asufficientquantityofcoppershotorgrindingsistobeusedtocoverallsurfacesofthespecimenwhetheritisinaventedglasscradleorembeddedinalayerofcoppershotonthebottomofthetest?ask.
42.3Theamountofcopperused,assuminganexcessofmetalliccopperispresent,isnotcritical.Theeffectivegalvaniccouplingbetweencopperandthetestspecimenmayhaveimportance(6).
11
Specimenshavingthesestructuresmustbetestedinthecopper–coppersulfate–16%sulfuricacidtest.
--`,`,``,``,`,,`,,,,,,```,`,,```-`-`,,`,,`,`,,`---
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42.4Thecoppershotorgrindingsmaybereusediftheyare1hat675°C.Careshouldbetakentoavoidcarburizingorcleanedinwarmtapwateraftereachtest.nitridingthespecimens.Theheattreatingisbestcarriedoutin43.SpecimenPreparation
airorneutralsalt.
43.1ThesizeofthesamplesubmittedfortestandtheareaNOTE18—Thesensitizingtreatment675°Cisperformedtochecktheeffectivenessofstabilizedand0.03%maximumcarbonmaterialsinfromwhichitistobetaken(endormiddleofcoil,midwayresistingcarbideprecipitation,hence,intergranularattack.
surfaceandcenter,andsoforth)isgenerallyspeci?edintheagreementbetweenthepurchaserandtheseller.Thetesting44.TestConditions
apparatusdictatesthe?nalsizeandshapeofthetestspecimen.44.1Thevolumeofacidi?edcoppersulfatetestsolutionThespecimencon?gurationshouldpermiteasyentranceandusedshouldbesufficienttocompletelyimmersethespecimensremovalthroughtheneckofthetestcontainer.
andprovideaminimumof8mL/cm2(50mL/in.2)ofspecimen43.1.1Table5maybeusedasaguidetodeterminesurfacearea.
acceptablespecimensizes.Theremayberestrictionsplacedon44.1.1Asmanyasthreespecimenscanbetestedinthesamespecimensizebythetestingapparatus.
container.Itisidealtohaveallthespecimensinone?asktobe43.1.2Specimensobtainedbyshearingshouldhavetheofthesamegrade,butitisnotabsolutelynecessary.Theshearededgesmachinedorgroundoffpriortotesting.Caresolutionvolume-to-samplearearatioistobemaintained.shouldbetakenwhengrindingtoavoidoverheatingor44.1.2Thetestspecimen(s)shouldbeimmersedinambient“burning.”A“squared”edgeisdesirable.
testsolution,whichisthenbroughttoaboilandmaintained43.2Anyscaleonthespecimensshouldberemovedme-boilingthroughoutthetestperiod.Begintimingthetestperiodchanicallyunlessaparticularsurface?nishistobeevaluated.whenthesolutionreachestheboilingpoint.
Chemicalremovalofscaleispermissiblewhenthisisthecase.NOTE19—MeasuresshouldbetakentominimizebumpingoftheMechanicalremovalofscaleshouldbeaccomplishedwithsolutionwhenglasscradlesareusedtosupportspecimens.Asmall120-gritiron-freealuminumoxideabrasive.
amountofcoppershot(eighttotenpieces)onthebottomofthe?askwill43.2.1Eachspecimenshouldbedegreasedusingacleaningconvenientlyservethispurpose.
solventsuchasacetone,alcohol,ether,oravapordegreaser44.1.3Thetimeofthetestshallbeaminimumof15h,priortobeingtested.
unlessalongertimeisagreeduponbetweenthepurchaserand43.3Allausteniticmaterialinthe“as-received”(mill-theproducer.Ifnot15h,thetesttimeshallbespeci?edontheannealed)conditionshouldbecapableofmeetingthistest.testreport.Freshtestsolutionwouldnotbeneededifthetest43.3.1Specimensofextra-low-carbonandstabilizedgradesweretorun48oreven72h.(Ifanyadherentcopperremainsaretestedaftersensitizingheattreatmentsat650to675°Conthespecimen,itmayberemovedbyabriefimmersionin(1200to1250°F),whichistherangeofmaximumcarbideconcentratednitricacidatroomtemperature.)
precipitation.Themostcommonlyusedsensitizingtreatmentis
NOTE20—Resultsintheliteratureindicatethatthistestismoresensitiveifitisrunforlongertimes(3,7).
TABLE5SizesofTestSpecimens
45.BendTest
TypeofMaterial
SizeofTestSpecimen
45.1Thetestspecimenshallbebentthrough180°andoverWroughtwireorrod:
adiameterequaltothethicknessofthespecimenbeingbentUpto6mm(?in.)indiameter,inclFulldiameterby75mm(3in.)(min)long
(seeFig.10).Innocaseshallthespecimenbebentovera
Over6mm(?in.)indiameter
Cylindricalsegment6mm(?in.)thickby25mm(1in.)(max)wideby75to125mm(3to5in.)longAWroughtsheet,strip,plates,or?atrolledproducts:
Upto5mm(3?16in.)thick,incl
Fullthicknessby9to25mm(\to1in.)wideby75mm(3in.)(min)long
Over5mm(3?16in.)thick
5to13mm(3?16to?in.)thickby9to25mm(\to1in.)wideby75mm(3in.)(min)longBTubing:
Upto38mm(1?in.)indiameter,inclFullring,25mm(1in.)wideCOver38mm(1?in.)indiameterAcircumferentialsegment75mm
(3in.)(min)longcutfroma25mm(1-in.)wideringDAWhenbendingsuchspecimens,thecurvedsurfaceshallbeontheoutsideofthebend.BOnesurfaceshallbeanoriginalsurfaceofthematerialundertestanditshallbeontheoutsideofthebend.Cold-rolledstriporsheetsmaybetestedinthethicknesssupplied.CRingsectionsarenot?attenedorsubjectedtoanymechanicalworkbeforetheyaresubjectedtothetestsolution.DSpecimensfromweldedtubesover38mm(1?in.)indiametershallbetakenwiththeweldontheaxisofthebend.
FIG.10ABentCopper–CopperSulfate–SulfuricAcid
TestSpecimen
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