ASTM-G31——金属的实验室浸泡腐蚀标准

Designation:G31–72(Reapproved2004)StandardPracticeforLaboratoryImmersionCorrosionTestingofMetals1ThisstandardisissuedunderthefixeddesignationG31;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(e)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thispractice2describesacceptedproceduresforandfactorsthatinfluencelaboratoryimmersioncorrosiontests,particularlymasslosstests.Thesefactorsincludespecimenpreparation,apparatus,testconditions,methodsofcleaningspecimens,evaluationofresults,andcalculationandreportingofcorrosionrates.Thispracticealsoemphasizestheimpor-tanceofrecordingallpertinentdataandprovidesachecklistforreportingtestdata.OtherASTMproceduresforlaboratorycorrosiontestsaretabulatedintheAppendix.(Warning—Inmanycasesthecorrosionproductonthereactivemetalstitaniumandzirconiumisahardandtightlybondedoxidethatdefiesremovalbychemicalorordinarymechanicalmeans.Inmanysuchcases,corrosionratesareestablishedbymassgainratherthanmassloss.)1.2ThevaluesstatedinSIunitsaretoberegardedasthestandard.Thevaluesgiveninparenthesesareforinformationonly.1.3Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.2.ReferencedDocuments2.1ASTMStandards:3A262PracticesforDetectingSusceptibilitytoIntergranu-larAttackinAusteniticStainlessSteelsE8TestMethodsforTensionTestingofMetallicMaterialsG1PracticeforPreparing,Cleaning,andEvaluatingCor-rosionTestSpecimensG4GuideforConductingCorrosionCouponTestsinFieldApplicationsG16GuideforApplyingStatisticstoAnalysisofCorrosionDataG46GuideforExaminationandEvaluationofPittingCorrosion3.SignificanceandUse3.1Corrosiontestingbyitsverynatureprecludescompletestandardization.Thispractice,ratherthanastandardizedpro-cedure,ispresentedasaguidesothatsomeofthepitfallsofsuchtestingmaybeavoided.3.2Experiencehasshownthatallmetalsandalloysdonotrespondaliketothemanyfactorsthataffectcorrosionandthat“accelerated”corrosiontestsgiveindicativeresultsonly,ormayevenbeentirelymisleading.Itisimpracticaltoproposeaninflexiblestandardlaboratorycorrosiontestingprocedureforgeneraluse,exceptformaterialqualificationtestswherestandardizationisobviouslyrequired.3.3Indesigninganycorrosiontest,considerationmustbegiventothevariousfactorsdiscussedinthispractice,becausethesefactorshavebeenfoundtoaffectgreatlytheresultsobtained.4.Interferences4.1Themethodsandproceduresdescribedhereinrepresentthebestcurrentpracticesforconductinglaboratorycorrosiontestsasdevelopedbycorrosionspecialistsintheprocessindustries.Forproperinterpretationoftheresultsobtained,thespecificinfluenceofcertainvariablesmustbeconsidered.Theseinclude:4.1.1Metalspecimensimmersedinaspecifichotliquidmaynotcorrodeatthesamerateorinthesamemannerasinequipmentwherethemetalactsasaheattransfermediuminheatingorcoolingtheliquid.Iftheinfluenceofheattransfereffectsisspecificallyofinterest,specializedprocedures(inwhichthecorrosionspecimenservesasaheattransferagent)mustbeemployed(1).44.1.2Inlaboratorytests,thevelocityoftheenvironmentrelativetothespecimenswillnormallybedeterminedbyconvectioncurrentsortheeffectsinducedbyaerationorboilingorboth.Ifthespecificeffectsofhighvelocityaretobestudied,specialtechniquesmustbeemployedtotransferthe1ThispracticeisunderthejurisdictionofASTMCommitteeG01onCorrosionofMetalsandisthedirectresponsibilityofSubcommitteeG01.05onLaboratoryCorrosionTests.CurrenteditionapprovedMay1,2004.PublishedMay2004.Originallyapprovedin1972.Lastpreviouseditionapprovedin1998asG31–72(1998).2ThispracticeisbaseduponNACEStandardTM-01-69,“TestMethod-LaboratoryCorrosionTestingofMetalsfortheProcessIndustries,”withmodifica-tionstorelatemoredirectlytoPracticesG1andG31andGuideG4.3ForreferencedASTMstandards,visittheASTMwebsite,@astm.org.ForAnnualBookofASTMStandardsvolumeinformation,refertothestandard’sDocumentSummarypageontheASTMwebsite.4Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendofthispractice.1Copyright©ASTMInternational,100BarrHarborDrive,POBoxC700,WestConshohocken,PA19428-2959,UnitedStates.environmentthroughtubularspecimensortomoveitrapidlypasttheplanefaceofacorrosioncoupon(2).Alternatively,thecouponmayberotatedthroughtheenvironment,althoughitisthendifficulttoevaluatethevelocityquantitativelybecauseofthestirringeffectsincurred.4.1.3Thebehaviorofcertainmetalsandalloysmaybeprofoundlyinfluencedbythepresenceofdissolvedoxygen.Ifthisisafactortobeconsideredinaspecifictest,thesolutionshouldbecompletelyaeratedordeaeratedinaccordancewith8.7.4.1.4Insomecases,therateofcorrosionmaybegovernedbyotherminorconstituentsinthesolution,inwhichcasetheywillhavetobecontinuallyorintermittentlyreplenishedbychangingthesolutioninthetest.4.1.5Corrosionproductsmayhaveundesirableeffectsonachemicalproduct.Theamountofpossiblec