ASTM+G150–99不锈钢电化学临界点蚀温度测试的标准试验方法

Designation:G150–99StandardTestMethodforElectrochemicalCriticalPittingTemperatureTestingofStainlessSteels1ThisstandardisissuedunderthefixeddesignationG150;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(e)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thistestmethodcoversaprocedurefortheevaluationoftheresistanceofstainlesssteelandrelatedalloystopittingcorrosionbasedontheconceptofthedeterminationofapotentialindependentcriticalpittingtemperature(CPT).1.2Thistestmethodsappliestowroughtandcastproductsincludingbutnotrestrictedtoplate,sheet,tubing,bar,forgings,andwelds,(seeNote1).NOTE1—ExamplesofCPTmeasurementsonsheet,plate,tubing,andweldedspecimensforvariousstainlesssteelscanbefoundinRef.(1).2Seetheresearchreport.31.3ThestandardparametersrecommendedinthistestmethodaresuitableforcharacterizingtheCPTofausteniticstainlesssteelsandotherrelatedalloyswithacorrosionresistancerangingfromthatcorrespondingtosolutionan-nealedUNSS31600(Type316stainlesssteel)tosolutionannealedUNSS31254(6%Mostainlesssteel).1.4ThistestmethodmaybeextendedtostainlesssteelsandotheralloysrelatedtostainlesssteelthathaveaCPToutsidethemeasurementrangegivenbythestandardparametersdescribedinthistestmethod.Appropriatetestpotentialandsolutionmustthenbedetermined.1.5ThevaluesstatedinSIunitsaretoberegardedasstandard.1.6Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.2.ReferencedDocuments2.1ASTMStandards:D1193SpecificationforReagentWater4E177PracticeforUseoftheTermsPrecisionandBiasinASTMTestMethods5E691PracticeforConductinganInterlaboratoryStudytoDeterminethePrecisionofaTestMethod5G1PracticeforPreparing,Cleaning,andEvaluatingCor-rosionTestSpecimens6G3PracticeforConventionsApplicabletoElectrochemicalMeasurementsinCorrosionTesting6G5ReferenceTestMethodforMakingPotentiostaticandPotentiodynamicAnodicPolarizationMeasurements6G15TerminologyRelatingtoCorrosionandCorrosionTesting6G46GuideforExaminationandEvaluationofPittingCorrosion6G107GuideforFormatsforCollectionandCompilationofCorrosionDataforMetalsforComputerizedDatabaseInput63.Terminology3.1Definitions:3.1.1criticalpittingtemperature(CPT)—thelowesttem-peratureonthetestsurfaceatwhichstablepropagatingpittingoccursunderspecifiedtestconditionsindicatedbyarapidincreasebeyondasetlimitofthemeasuredanodiccurrentdensityofthespecimen.3.1.2pittingpotentialrange—therangeofmeasuredpoten-tialswherepittingisinitiated.Thispotentialrangeonlyexistsabovetheminimumcriticalpittingtemperature;seealsoAppendixX1.3.1.3potentialindependentCPT—theCPTdeterminedatapotentialabovethepittingpotentialrange,butbelowthetranspassivepotential;seealsoAppendixX1.3.1.4potentialdependentCPT—theCPTdeterminedatapotentialwithinthepittingpotentialrangeofthetestedmaterial;seealsoAppendixX1.3.1.5temperatureramp—therate(°C/min)atwhichthetesttemperatureisincreasedduringthetest.3.2signconventions—thesignconventionsusedinthisprocedureareinagreementwithPracticeG3.3.3Unlessotherwisestated,thistestmethodusesthegeneralterminologyrelatingtocorrosionandcorrosiontestingasdefinedinTerminologyG15.1ThistestmethodisunderthejurisdictionofG-1onCorrosionofMetalsandisthedirectresponsibilityofSubcommitteeG01.11onElectrochemicalMeasurementsinCorrosionTesting.CurrenteditionapprovedJan.10,1999.PublishedMarch1999.OriginallypublishedasG150–97.LastpreviouseditionG150–97.2Theboldfacenumbersinparenthesisrefertothelistofreferencesattheendofthisstandard.3SeeASTMResearchReportG01-1017.AvailablefromASTMHeadquarters.4AnnualBookofASTMStandards,Vol11.01.5AnnualBookofASTMStandards,Vol14.02.6AnnualBookofASTMStandards,Vol03.02.1AMERICANSOCIETYFORTESTINGANDMATERIALS100BarrHarborDr.,WestConshohocken,PA19428ReprintedfromtheAnnualBookofASTMStandards.CopyrightASTM4.SummaryofTestMethod4.1Thetestmethoddeterminesthepotentialindependentcriticalpittingtemperature(CPT)bywayofapotentiostatictechniqueusingatemperaturescanandaspecimenholderthatisdesignedtoeliminatetheoccurrenceofcrevicecorrosion(seeFig.1).Thespecimenisexposed,eitherentirelyorinpart,dependingontestcellconfigurationtoa1MNaClsolution,initiallyat0°C.Afteraninitialtemperaturestabilizationperiod,thesolutionisheatedatarateof1°C/min.About60sbeforethetemperaturescaniscommenced,thespecimenisanodicallypolarizedtoapotentialabovethepittingpotentialrange.Thispotentialisheldconstantduringthewholetem-peraturescan.Apotentialof700mVversusSCE(25°C)hasbeenfoundsuitableformoststainlesssteels.Thecurrentismonitoredduringthetemperaturescan,andtheCPTisdefinedasthetemperatureatwhichthecurrentincreasesrapidly,whichforpracticalreasonsisdefinedasthetemperatureatwhichthecurrentdensityexceeds100μA/cm2for60s.Pittingonthespecimenisconfirmedvisuallyafterthetest.5.SignificanceandUse5.1Thistestmethodprovidesapredictionoftheresistanc