ASTM E1558-2004 Standard Guide for Electrolytic P

Designation:E1558−09(Reapproved2014)StandardGuideforElectrolyticPolishingofMetallographicSpecimens1ThisstandardisissuedunderthefixeddesignationE1558;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thisguidedealswithelectrolyticpolishingasameansofpreparationofspecimensformetallographicpurposes.Proceduresaredescribedforpolishingavarietyofmetals.NOTE1—References(1-133)2onelectrolyticpolishingwillprovidethereaderwithspecificinformationbeyondthescopeofthisguide.1.2ThevaluesstatedinSIunitsaretoberegardedasstandard.Nootherunitsofmeasurementareincludedinthisstandard.1.3Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.SpecificsafetyprecautionsaredescribedinSection5and6.3.1.2.ReferencedDocuments2.1ASTMStandards:3E7TerminologyRelatingtoMetallographyE407PracticeforMicroetchingMetalsandAlloys3.Terminology3.1Definitions—AlltermsusedinthisguideareeitherdefinedinTerminologyE7orarediscussedin3.2.3.2DefinitionsofTermsSpecifictoThisStandard:3.2.1electrolyticpolish(electropolish)—Amethodofpol-ishingmetalsandalloysinwhichmaterialisremovedfromthesurfacebymakingthemetaltheanodeinanelectrolyticbath.4.SignificanceandUse4.1AdvantagesofElectrolyticPolishing:4.1.1Forsomemetals,ahighqualitysurfacefinishcanbeproducedthatisequivalentto,orbetterthan,thatwhichcanbeobtainedbymechanicalmethods.4.1.2Onceprocedureshavebeenestablished,satisfactoryresultscanbeobtainedrapidlywithreproducibility.4.1.3Therecanbeamarkedsavingoftimeifmanyspecimensofthesamematerialarepolishedsequentially.4.1.4Electropolishingaselectedareaonthesurfaceofarelativelylargemetalpartcanbeaccomplishednondestructively,thatis,withouttheneedforsectioningtoremoveapiece.4.1.5Soft,single-phasemetals,whichmaybedifficulttopolishbymechanicalmethods,maybesuccessfullyelectrop-olished.4.1.6Thetruemicrostructureofaspecimencanbeobtainedbecauseartifacts(suchasdisturbedmetal,scratches,andmechanicaltwins)producedonthesurface,evenbycarefulgrindingandmechanicalpolishingoperations,canberemoved.Thesefeaturesareimportantinlow-loadhardnesstesting,X-raydiffractionstudies,andinelectronmicroscopy,wherehigherresolutionputsapremiumonundistortedmetalsur-faces.4.1.7Afterelectropolishingiscompleted,etchingcanoftenbeaccomplishedbyreducingthevoltage(generallytoaboutone-tenththatrequiredforpolishing)forashorttimebeforeitisturnedoff.NOTE2—Notallelectropolishingsolutionsproducegoodetchingresults.4.2DisadvantagesofElectrolyticPolishing:4.2.1Manyofthechemicalmixturesusedinelectropolish-ingarepoisonousordangerousifnotproperlyhandled(seeSection5).Thesehazardsaresimilartothoseinvolvedinthemixingandhandlingofetchants,seeTestMethodsE407.4.2.2Inmulti-phasealloys,thepolishingrateofeachphasemaybedifferent.Theresultmaybeanon-planarsurface.4.2.3Electropolishedsurfacesmaybeslightlyundulatedratherthanperfectlyplanarand,therefore,maynotbesuitableforexaminationatallmagnifications.4.2.4Therateofpolishinginareasadjacenttovariousinhomogeneities,suchasnonmetallicinclusionsandvoids,isusuallygreaterthanthatinthesurroundingmatrixandtendstoexaggeratethesizeoftheinclusionsandvoids.1ThisguideisunderthejurisdictionofASTMCommitteeE04onMetallographyandisthedirectresponsibilityofSubcommitteeE04.01onSpecimenPreparation.CurrenteditionapprovedOct.1,2014.PublishedDecember2014.Originallyapprovedin1993.Lastpreviouseditionapprovedin2009asE1558–09.DOI:10.1520/E1558-09R14.2Theboldfacenumbersinparenthesesrefertothereferencesattheendofthisstandard.3ForreferencedASTMstandards,visittheASTMwebsite,@astm.org.ForAnnualBookofASTMStandardsvolumeinformation,refertothestandard’sDocumentSummarypageontheASTMwebsite.Copyright©ASTMInternational,100BarrHarborDrive,POBoxC700,WestConshohocken,PA19428-2959.UnitedStates1CopyrightbyASTMInt'l(allrightsreserved);SunMar2922:36:07EDT2015Downloaded/printedby(TsinghuaUniversity)pursuanttoLicenseAgreement.Nofurtherreproductionsauthorized.4.2.5Dimples,pits,andwavinesslimitapplicationsinvolv-ingsurfacephenomena,coatings,interfaces,andcracks.Edgestendtobeattackedpreferentially,resultinginedgerounding.4.2.6Artifactsmaybeproducedbyelectropolishing.4.2.7Specimenmountingmaterialsmayreactwiththeelectrolyte.4.2.8Theelectropolishedsurfacesofcertainmaterialsmaybepassiveanddifficulttoetch.4.2.9Metalremovalratesbyelectropolishingareusuallyquitelow,typicallyabout1µm/min,andallofthepriorinduceddamagefromcuttingandgrindingmaynotbere-movedifpreparationisstoppedaftera600-gritSiCgrindandelectropolishingtimesareshort.4.2.10Alargenumberofelectrolytesmaybeneededtopolishthevarietyofmetalsencounteredbyagivenlaboratory.Considerabletimemayberequiredtodevelopaprocedureforanewalloy.5.GeneralSafetyPrecautions5.1Befo