ASTM A967-2001 不锈钢零件化学钝化处理的标准规范

ChemicalPassivationTreatmentsforStainlessSteelParts1ThisstandardisissuedunderthefixeddesignationA967;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(e)indicatesaneditorialchangesincethelastrevisionorreapproval.

e1NOTE—Paragraph3.1.1.5wasdeletededitoriallyinApril2002.Paragraph10.2wascorrectededitoriallyinApril2002.

1.Scope

1.1Thisspecificationcoversseveraldifferenttypesofchemicalpassivationtreatmentsforstainlesssteelparts.Itincludesrecommendationsandprecautionsfordescaling,cleaning,andpassivationofstainlesssteelparts.Itincludesseveralalternativetests,withacceptancecriteria,forconfirma-tionofeffectivenessofsuchtreatmentsforstainlesssteelparts.1.2PracticesforthemechanicalandchemicaltreatmentsofstainlesssteelsurfacesarediscussedmorethoroughlyinPracticeA380.

1.3Severalalternativechemicaltreatmentsaredefinedforpassivationofstainlesssteelparts.AppendixX1givessomenonmandatoryinformationandprovidessomegeneralguide-linesregardingtheselectionofpassivationtreatmentappropri-atetoparticulargradesofstainlesssteelbutmakesnorecommendationsregardingthesuitabilityofanygrade,treat-ment,andacceptancecriteriaforanyparticularapplicationorclassofapplications.

1.4Thetestsinthisspecificationareintendedtoconfirmtheeffectivenessofpassivation,particularlywithregardtotheremovaloffreeironandotherexogenousmatter.Thesetestsincludethefollowingpractices:

1.4.1PracticeA—WaterImmersionTest,1.4.2PracticeB—HighHumidityTest,1.4.3PracticeC—SaltSprayTest,1.4.4PracticeD—CopperSulfateTest,

1.4.5PracticeE—PotassiumFerricyanide–NitricAcidTest,and

1.4.6PracticeF—FreeIronTest.

1.5Thevaluesstatedininch-poundunitsaretoberegardedasthestandard.TheSIunitsgiveninparenthesesareforinformationonly.

1.6Thefollowingprecautionarycaveatpertainsonlytothetestmethodportions,Sections14through18ofthisspecifica-tion:Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappropriatesafetyand

ThisspecificationisunderthejurisdictionofASTMCommitteeA01onSteel,StainlessSteel,andRelatedAlloysandisthedirectresponsibilityofSubcommitteeA01.14onMethodsofCorrosionTesting.

CurrenteditionapprovedOct.10,2001.PublishedDecember2001.OriginallypublishedasA967–96.LastprevioiuseditionA967–99.

1healthpracticesanddeterminetheapplicabilityofregulatorylimitationspriortouse.

2.ReferencedDocuments2.1ASTMStandards:

A380PracticeforCleaning,Descaling,andDepassivationofStainlessSteelParts,Equipment,andSystems2B117PracticeforOperatingSaltSpray(Fog)Apparatus3B2PracticeforPreparationofandElectroplatingonStainlessSteel42.2FederalSpecification:

QQ-P-35CPassivationTreatmentsforCorrosion-ResistantSteels53.Terminology

3.1DefinitionofTermSpecifictoThisStandard—Itisnecessarytodefinewhichoftheseveralcommonlyuseddefinitionsofthetermpassivationwillbeusedinthisspecification.(SeeDiscussion.)

3.1.1Discussion—Stainlesssteelsareautopassivatinginthesensethattheprotectivepassivefilmisformedspontaneouslyonexposuretoairormoisture.Thepresenceofexogenoussurfacecontamination,includingdirt,grease,freeironfromcontactwithsteeltooling,andsoforth,mayinterferewiththeformationofthepassivefilm.Thecleaningofthesecontami-nantsfromthestainlesssteelsurfacewillfacilitatethespon-taneouspassivationbyallowingtheoxygenuniformaccesstothesurface.Thepassivefilmmaybeaugmentedbychemicaltreatmentsthatprovideanoxidizingenvironmentforthestainlesssteelsurface.

3.1.1.1Inthisspecification,passivation,unlessotherwisespecified,isdefinedasthechemicaltreatmentofastainlesssteelwithamildoxidant,suchasanitricacidsolution,forthepurposeoftheremovaloffreeironorotherforeignmatter,butwhichisgenerallynoteffectiveinremovalofheattintoroxidescaleonstainlesssteel.Inthecaseofstainlesssteelswithadditionsofsulfurforthepurposeofimprovedmachinability,

AnnualBookofASTMStandards,Vol01.03.AnnualBookofASTMStandards,Vol03.02.4AnnualBookofASTMStandards,Vol02.05.5AvailablefromSuperintendentofDocuments,U.S.GovernmentPrintingOffice,Washington,DC20402.

32Copyright©ASTMInternational,100BarrHarborDrive,POBoxC700,WestConshohocken,PA19428-2959,UnitedStates.

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passivationmayalsoincludetheremovalofsulfidesfromthesurfaceofthemetalforthepurposeofmaximizingcorrosionresistance.

3.1.1.2Theformationoftheprotectivepassivefilmonastainlesssteel,alsocalledpassivationinamoregeneralcontext,willoccurspontaneouslyinairorotheroxygen-containingenvironmentwhenthestainlesssteelsurfaceisfreeofoxidescaleandexogenousmatter.

3.1.1.3Chemicaltreatments,suchassodiumdichromatesolutions,mayfacilitatethemorerapidformationofthepassivefilmonastainlesssteelsurfacealreadyfreeofscaleorforeignmatter.Suchtreatments,alsosometimescalledpassi-vationincommonusage,aredesignatedaspost-cleaningtreatmentsinthisspecificationinordertodistinguishthemfromchemicaltreatmentscapableofremovingfreeironfromstainlesssteels.

3.1.1.4Thechemicaltreatmentscapableofremovingheattintoroxidescalefromstainlesssteelandcapableofdissolvingthestainlesssteelitself,typicallycalledpickling,aresubstan-tiallymoreaggressivethantreatmentsusedforpassivation,asdefinedin3.1.1.1.Thesurfaceofstainlesssteelthathasbeenpickledisfreeofscale,freeiron,andexogenousforeignmatter,anddoesnotrequireaseparatetreatmentforpassiva-tionasdefinedin3.1.1.1.Thepassivationprocessdefinedin3.1.1.2willoccurwithoutfurtherchemicaltreatmentbutmaybeaugmentedandimprovedbythepost-cleaningtreatmentsdefinedin3.1.1.3.

3.1.1.5Electrochemicaltreatments,includingelectropick-lingandelectropolishingcapableofremovingheattintoroxidescalefromstainlesssteelandcapableofdissolvingthestainlesssteelitself,aresubstantiallymoreaggressivethantreatmentsusedforpassivation,asdefinedin3.1.1.1.Thesurfaceofstainlesssteelresultingfromthesetreatmentsisfreeofscale,freeiron,andexogenousforeignmatter,anddoesnotrequireaseparatetreatmentforpassivationasdefinedin3.1.1.1.Thepassivationprocessdefinedin3.1.1.2willoccurwithoutfurtherchemicaltreatment,butmaybeaugmentedandim-provedbythepost-cleaningtreatmentsdefinedin3.1.1.3.Statementsregardingchemicaltreatments,unlessotherwisespecified,aretakentoincludeelectrochemicaltreatments.4.OrderingInformation

4.1Itistheresponsibilityofthepurchasertospecifyatestpracticeappropriatetoanyparticularmaterialandapplication.ThisspecificationwaswrittenforthepurposeofprovidinganalternativetoUnitedStatesFederalSpecificationQQ-P-35C.Determinationofthesuitabilityofthisspecificationforthatpurposeistheresponsibilityofthepurchaser.

4.2Unlessspecifiedbythepurchaser,thechemicaltreat-mentappliedtothestainlesssteelpartsshallbeselectedbythesellerfromamongthelistedpassivationtreatments.

5.MaterialsandPreparationforPassivationTreatments5.1Thepassivationtreatmentsshallbeofoneormoreofthefollowingtypes.Theeffectivenessofaparticulartreatmentforaparticulargradeofstainlesssteelinaparticularapplicationisdemonstratedbymeetingthespecifiedtestingrequirements:5.1.1Treatmentsinnitricacid,5.1.2Treatmentsincitricacid,

5.1.3Otherchemicaltreatments,includingelectrochemicaltreatments,

5.1.4Neutralization,and

5.1.5Post-cleaningtreatments.5.2Materials:

5.2.1Thechemicalsusedforpassivationtreatmentsshallproducepassivatedsurfacesthatmeettherequirementsofoneormoreofthetestsofthisspecification.Attentionshallbegiventomaintainingadequatevolume,concentration,purity,andtemperaturecontrolappropriatetothesizeandamountofstainlesssteeltobetreated.

5.2.2Theprocessorshallmaintainarecordwithregardtoconcentrationandtemperatureofthepassivationsolutionsufficienttodemonstratethatthespecifiedpassivationcondi-tionsweremaintainedforeachlotofstainlesssteelpartsprocessed.Suchrecordsshallbeavailableforinspectionwhenspecifiedinthepurchaseorder.Theprocessorisnotrequiredtorevealtheprecisecompositionofproprietarychemicalmix-turesbutshallmaintainauniqueidentificationofthemixturethatwillensureitsaccuraterepresentationforsubsequentuse.5.2.3Theprocessorshallberesponsibleforthesafedis-posalofallmaterialgeneratedbythisprocess.5.3PreparationforPassivationTreatments:

5.3.1Thepretreatmentmethodsandproceduresusedpriortothepassivationtreatment,includingmechanicalandchemi-calmethods,singlyorincombination,fordescalingandpickling,shallbeinaccordancewithPracticeA380.Whenelectrochemicalcleaningisrequired,itshallbeperformedinaccordancewithPracticeB2.

5.3.2Theresultingpretreatedsurfaceshallbesubstantiallyfreeofoil,grease,rust,scale,andotherforeignmatter.

5.3.3Whenthefinalpretreatmentofapartincludespicklingoftheentiresurfaceofthepart,nofurtherpassivationtreatmentisrequiredpriortotestingofthesurfaceunlessspecifiedbythepurchaser.

6.TreatmentsinNitricAcidSolutions6.1PassivationTreatment:

6.1.1Stainlesssteelpartsshallbetreatedinoneofthefollowingaqueoussolutionsandmaintainedwithinthespeci-fiedtemperaturerangeforthespecifiedtime.

6.1.1.1Nitric1—Thesolutionshallcontain20to25volumepercentofnitricacidand2.5+0.5weightpercentofsodiumdichromate.Thepartsshallbeimmersedforaminimumof20minatatemperatureintherangefrom120to130°F(49to°C).

6.1.1.2Nitric2—Thesolutionshallcontain20to45volumepercentofnitricacid.Thepartsshallbeimmersedforaminimumof30minatatemperatureintherangefrom70to90°F(21to32°C).

6.1.1.3Nitric3—Thesolutionshallcontain20to25volumepercentnitricacid.Thepartsshallbeimmersedforaminimumof20minatatemperatureintherangefrom120to140°F(49to60°C).

6.1.1.4Nitric4—Thesolutionshallcontain45to55volumepercentofnitricacid.Thepartsshallbeimmersedforaminimumof30minatatemperatureintherangefrom120to130°F(49to°C).

6.1.1.5Nitric5—Othercombinationsoftemperature,time,andconcentrationofnitricacid,withorwithoutotherchemi-cals,includingaccelerants,inhibitors,orproprietarysolutions,capableofproducingpartsthatpassthespecifiedtestrequire-ments.

6.2WaterRinse—Immediatelyafterremovalfromthepas-sivatingsolutionthepartsshallbethoroughlyrinsed,usingstagnant,countercurrent,orspraywashessinglyorincombi-nation,withorwithoutaseparatechemicaltreatmentforneutralization(see9.1)ofthepassivationmedia,withafinalrinsebeingcarriedoutusingwaterwithamaximumtotalsolidscontentof200ppm.

7.TreatmentsinCitricAcid7.1PassivationTreatment:

7.1.1Stainlesssteelpartsshallbetreatedinoneofthefollowingaqueoussolutionsandmaintainedwithinthespeci-fiedtemperaturerangeforthespecifiedtime.

7.1.1.1Citric1—Thesolutionshallcontain4to10weightpercentofcitricacid.Thepartsshallbeimmersedforaminimumof4minatatemperatureintherangefrom140to160°F(60to71°C).

7.1.1.2Citric2—Thesolutionshallcontain4to10weightpercentofcitricacid.Thepartsshallbeimmersedforaminimumof10minatatemperatureintherangefrom120to140°F(49to60°C).

7.1.1.3Citric3—Thesolutionshallcontain4to10weightpercentofcitricacid.Thepartsshallbeimmersedforaminimumof20minatatemperatureintherangefrom70to120°F(21to49°C).

7.1.1.4Citric4—Othercombinationsoftemperature,time,andconcentrationofcitricacid,withorwithoutotherchemi-calstoenhancecleaning,includingaccelerants,inhibitors,orproprietarysolutionscapableofproducingpartsthatpassthespecifiedtestrequirements.

7.1.1.5Citric5—Othercombinationsoftemperature,time,andconcentrationsofcitricacid,withorwithoutotherchemi-calstoenhancecleaning,includingaccelerants,inhibitors,orproprietarysolutionscapableofproducingpartsthatpassthespecifiedtestrequirements.ImmersionbathtobecontrolledatapHof1.8–2.2.

7.2WaterRinse—Immediatelyafterremovalfromthepas-sivatingsolution,thepartsshallbethoroughlyrinsed,usingstagnant,countercurrent,orspraywashes,singlyorincombi-nation,withorwithoutaseparatechemicaltreatmentforneutralizationofthepassivationmedia(see9.2),withafinalrinsebeingcarriedoutusingwaterwithamaximumtotalsolidscontentof200ppm.

8.TreatmentsinOtherChemicalSolutions,IncludingElectrochemicalTreatments

8.1Itisrecognizedthatthepurposeofremovalofallexogenousmatterfromastainlesssteelsurface,includingtheremovaloffreeiron,canbeaccomplishedbydifferentmedia,withpotentialforbenefitstobegainedfromuseofproprietaryskillsandart,includingproprietarypassivationmedia.Suchtreatmentsmayincludeexternallyapplyinganelectricalpo-tentialonthestainlesssteelparts,asinthecaseofelectropol-ishing.Thesuitabilityofsuchpassivationtreatmentsforusein

meetingtherequirementsofthisspecificationshallbedeter-minedbythecapabilityoftheprocessedpartsmeetingthespecifiedtestrequirements.

8.2Stainlesssteelpartsshallbetreatedinaspecifiedaqueoussolution,withorwithoutexternallyappliedelectricalpotential,andmaintainedwithinaspecifiedtemperaturerangeforatimesufficientfortheprocessedpartstomeetthespecifiedtestrequirement.

8.3WaterRinse—Immediatelyafterremovalfromthepas-sivatingsolution,thepartsshallbethoroughlyrinsed,usingstagnant,countercurrent,orspraywashes,singlyorincombi-nation,withorwithoutaseparatechemicaltreatmentforneutralizationofthepassivationmedia(see9.2),withafinalrinsebeingcarriedoutusingwaterwithamaximumtotalsolidscontentof200ppm.

9.Neutralization

9.1Thechemicalreactionsofthepassivatingmediaonthesurfaceofthestainlesssteelshallbestoppedbyrinsingofthestainlesssteelpart,withorwithoutaseparateneutralizationtreatment.

9.2Thesuitabilityofaneutralizationprocedureisdeter-minedbythecapabilityoftheprocessedpartsmeetingthespecifiedtestrequirements.(SeeNote1.)

NOTE1—Theselectionofmediumandproceduresforaneutralizationdependsofthechemistryofthepassivationandoneconomicconsider-ations.Anexampleofaneutralizingtreatmentwouldbeimmersionofthepartforaminimumof30mininasolutionof5%NaOHat160to180°F(71to82°C),followedbyawaterrinse.

10.Post-CleaningTreatments

10.1Althoughthepassivefilmcharacteristicofstainlesssteelwillformspontaneouslyinairoranyotheroxygen-containingenvironment,theprocessorshall,whenspecified,applyachemicaltreatmentthatwillacceleratetheformationofthepassivefilmonachemicallycleanstainlesssteelsurface.Anexampleofamediumthatservestoacceleratetheforma-tionofthepassivefilmbutdoesnotcontributetotheremovaloffreeironfromthestainlesssteelsurfacewouldbeanaqueoussolutionofsodiumdichromate.

10.2Whenspecified,withinonehourafterthefinalwaterrinseasrequiredin6.2,7.2,or8.3,allferriticandmartensiticsteelpartsshallbeimmersedinanaqueoussolutioncontaining4to6weightpercentofsodiumdichromateatatemperatureintherangefrom140to160°F(60to71°C)foraminimumof30min,followedbyarinseinaccordancewith6.2,7.2,or8.3.Thepartsshallthenbethoroughlydried.

10.3Thepurchasermayspecifyotherpost-cleaningtreat-ments.

11.Finish

11.1Thepassivatedpartsshallexhibitachemicallycleansurfaceandshall,onvisualinspection,shownoetching,pitting,orfrostingresultingfromthepassivationprocedures.12.TestingAgency

12.1Whenrequired,thepurchasershallbepermittedtoperformsuchinspectionsasnecessarytodeterminethatthetestingagencyiscapableofperformingthespecifiedtest.

13.Lot,FrequencyofTesting,andSelectionofTest

13.1DefinitionofLot—Alotshallconsistofoneofthefollowing,attheoptionoftheprocessor:

13.1.1Thepassivatedpartsofsimilaralloyandmanufac-turingmethodsthatarepretreatedandpassivatedinasingledayorwithinatimeframethatwillensureconsistentpassiva-tionresults;

13.1.2Thepassivatedpartsofthesameproductofonesizefromoneheatinoneshipment;or

13.1.3Whenfewpartsareinvolved,thepassivatedpartsfromanentireproductionrun.

13.2Unlessagreaterfrequencyoftestingisspecifiedonthepurchaseorder,onetestperlotshallbesufficient.

13.3Oneormoreofthefollowingtests,whenspecifiedonthepurchaseorder,shallbeperformedoneachlotofstainlesssteelparts.Notallofthefollowingtestsaresuitableforallgradesofstainlesssteel.(SeeNote2.)

13.3.1PracticeA—WaterImmersionTest,13.3.2PracticeB—HighHumidityTest,13.3.3PracticeC—SaltSprayTest,

13.3.4PracticeD—CopperSulfateTest,and

13.3.5PracticeE—PotassiumFerricyanide–NitricAcidTest.

NOTE2—Someofthetestsmayproducepositiveindicationsnotassociatedwiththepresenceoffreeirononthestainlesssteelsurface.AnexamplewouldbeapplicationofPracticeConsomelesser-alloyedmartensiticorferriticstainlesssteels.

14.PracticeA—WaterImmersionTest

14.1Thistestisusedforthedetectionoffreeironoranyotheranodicsurfacecontaminantsonstainlesssteel.

14.2Thesamplerepresentingthelotofpassivatedpartsshallbealternatelyimmersedinanon-rustingtankofdistilledwaterfor1handallowedtodryinairfor1h.Thiscycleshallberepeatedaminimumoftwelvetimes.

14.3Thetestedsampleshallnotexhibitrustorstainingattributabletothepresenceoffreeironparticlesembeddedinthesurface.

15.PracticeB—HighHumidityTest

15.1Thistestisusedforthedetectionoffreeironoranyotheranodicsurfacecontaminantsonstainlesssteel.

15.2Thetestshallbeperformedusingahumiditycabinetcapableofmaintainingthespecifiedtestconditions.

15.3Thesamplerepresentingthelotofpassivatedpartsshallbecleanedbyimmersioninacetoneormethylalcoholorbyswabbingwithacleangauzesaturatedwithacetoneormethylalcohol,anddriedinaninertatmosphereordesiccatedcontainer.Thecleanedanddriedpartshallbesubjectedto9763%humidityat10065°F(3863°C)foraminimumof24h.

15.4Thetestedsampleshallnotexhibitrustorstainingattributabletothepresenceoffreeironparticlesimbeddedinthesurface.

16.PracticeC—SaltSprayTest

16.1Thistestisusedforthedetectionoffreeironoranyotheranodicsurfacecontaminantsonstainlesssteel.

16.2ThesamplerepresentingthelotofpassivatedpartsshallbetestedbythesaltspraytestconductedinaccordancewithPracticeB117foraminimumof2husinga5%saltsolution.

16.3Thetestedsampleshallnotexhibitrustorstainingattributabletothepresenceoffreeironparticlesimbeddedinthesurface.

17.PracticeD—CopperSulfateTest

17.1Thistestisrecommendedforthedetectionoffreeirononthesurfaceofausteniticstainlesssteelsinthe200and300series,precipitationhardenedstainlesssteels,andferritic400seriesstainlesssteelshavingaminimumof16%chromium.Thistestisnotrecommendedformartensitic400seriesstainlesssteelsorforferritic400seriesstainlesssteelswithlessthan16%chromiumbecausethesesteelswillgiveapositiveindicationirrespectiveofthepresenceorabsenceofanodicsurfacecontaminants.Thistestshallnotbeappliedtopartstobeusedinfoodprocessing.

17.2Thetestsolutionispreparedbydissolving4gofcoppersulfatepentahydrate(CuSOwhich1mLofsulfuric4·5H2O)in250mLofdistilledwatertoacid(HAqueouscoppersulfatesolutions2SO4,spgr1.84)hasbeenadded.morethantwoweeksoldshallnotbeusedforthistest.

17.3Thetestsolutionisswabbedonthesurfaceofthesamplerepresentingthelotofpassivatedparts,applyingadditionalsolutionasneededtokeepthesurfacewetforaperiodofatleast6min.Attheendofthisperiod,thesurfaceshallbecarefullyrinsedanddriedwithcaretakennottodisturbcopperdepositsifpresent.

17.4Thetestedsampleshallnotexhibitcopperdeposits.18.PracticeE—PotassiumFerricyanide–NitricAcidTest18.1Thistestisrecommendedwhendetectionofverysmallamountsoffreeironisrequired.Itisrecommendedfordetectionoffreeirononaustenitic200and300seriesstainlesssteels.Thistestisnotrecommendedfordetectionoffreeirononferriticormartensitic400seriesstainlesssteels,becausethesesteelswillgiveapositiveindicationirrespectiveofthepresenceorabsenceofanodicsurfacecontaminants.Thistestshallnotbeappliedtopartstobeusedinfoodprocessing.18.2Thetestsolutionispreparedbyadding10gofchemicallypurepotassiumferricyanideto500mLofdistilledwater,adding30mLof70%nitricacid,agitatinguntilalloftheferricyanideisdissolved,anddilutingto1000mLwithdistilledwater.Thetestsolutionshallbemixedfreshonthedayofthetest.

18.3Thetestsolutionisswabbedonthesurfaceofthesamplerepresentingthelotofpassivatedparts.Theformationofadarkbluecolorwithin30sdenotesthepresenceofmetalliciron.

18.4Thetestedsampleshallnotexhibitthedarkbluecolorindicativeoffreeirononthesurface.

18.5Whenthetestisnegative,thesurfaceshallbethor-oughlywashedwithwarmwatertoremovalalltracesofthetestsolution.Whenthetestispositive,thedarkbluestainshallberemovedwithasolutionof10%aceticacidand8%oxalicacid,followedbyathoroughhotwaterrinse.

19.PracticeF—FreeIronTest

19.1Thistestisusedforthedetectionoffreeirononthesurfaceofstainlesssteel.ItisespeciallyusefulforlargepartsthathavebeenuniformlycleanedbutthatareinconvenientforreasonsofsizeofequipmentoreaseofhandlingoftheparttoplaceintheenvironmentsdefinedinPracticeA(Section14)orPracticeB(Section15).Unlessotherwisespecifiedbythepurchaser,thenumberoftestsandthelocationsofthetestsshallbeattheoptionoftheprocessortoassurearepresentativetestingofthepart.

19.2Thetestisperformedbyplacingacleanclothpadthathasbeenthoroughlysoakedwithdistilledordeminaralizedwateronthesurfaceofthepartataparttemperatureof50°F(10°C)orgreaterforaperiodofnotlessthan60minutes.Theclothshallbeincontactwiththesteelforanareaofatleast20squareinches(130cm2).Thepadshallbemaintainedwetthroughthetestperiod,eitherbyamethodofretardingexternalevaporation,bythefurtheradditionofpotablewater,orbybackingthepadwithaspongeorsimilarwatersource.Theclothpadusedshallbeusedforonlyonesuchtest,beingchangedforeachtestsoastoavoidriskofcontamination.Afterremovaloftheclothpad,thesurfaceofthepartshallbeallowedtodryinairbeforeinspection.

19.3Thetestedpartshallnotexhibitrustorstainingattributabletothepresenceoffreeironparticlesembeddedinthesurface.

20.RejectionandRetest

20.1Anylotfailingtomeetthespecifiedtestrequirementsofthepurchaseordershallberejected.Arejectedlotmay,attheoptionoftheprocessor,bere-passivated,withorwithoutre-pretreatment,andthenberetested.Thenumberofsamplestestedfromalotsubjecttoretestshallbetwicetheoriginalspecifiedtestfrequency,tothelimitofthenumberofpiecesinthelot.Allsamplesmustpassthespecifiedacceptancecriterionforthespecifiedtestfortheretestedlottobeaccepted.21.PrecisionandBias

21.1NostatementismadeconcerningeithertheprecisionorbiasofPracticesA,B,C,D,andEbecausetheresultsstatemerelywhetherthereisconformancetothecriteriaforsuccessspecifiedintheprocedure.

22.Certification

22.1Whenspecifiedinthepurchaseorder,areportofthepracticeandtestsused,includingtherecordofprocesscondi-tionswhenspecifiedinaccordancewith3.1.1.2,shallbesuppliedtothepurchaser.

APPENDIX

(NonmandatoryInformation)

X1.INFORMATIONREGARDINGPASSIVATIONTREATMENTS

NOTEX1.1—ThefollowinginformationisbasedonasectionofFederalSpecificationQQ-P-35C(Oct.28,1988)identifiedasinformationofageneralorexplanatorynaturethatmaybehelpful,butisnotmandatory.Minorchangeshavebeenmadeinthetexttofacilitatereferencestothemaindocumentandtocorrecttechnicalinaccuracies.

X1.1IntendedUse—Thepassivationtreatmentsprovidedbythisspecificationareintendedtoimprovethecorrosionresistanceofpartsmadefromstainlesssteelsofalltypes.X1.1.1Duringprocessingoperationssuchasforming,ma-chining,tumbling,andlapping,ironparticlesorotherforeignparticlesmaybecomesmearedoverorimbeddedintothesurfaceofstainlesssteelparts.Theseparticlesmustbere-movedortheywillappearasrustorstainspots.Thisconditionmaybepreventedbychemicallytreatingthepartstoremovetheironparticlesorotherforeignparticles,andthenallowingthepassivefilmtoformonthecleanedsurface,withorwithoutchemicalenhancementoftheformationofthisoxidefilm.X1.1.2Thisspecificationisnotintendedfortheblackoxidecoatingofpartstypicallyusedforphotographicoropticalinstruments.

X1.2OrderingData—Purchasersshouldselectthepre-ferredoptionspermittedbythisspecificationandincludethefollowinginformationinthepurchaseorder:

X1.2.1Title,number,anddateofthisspecification;

X1.2.2Identificationofmaterialbytypeandapplicableproductspecification;

X1.2.3Testpracticestobeimposed(see1.4);

X1.2.4Definitionoflotsize,ifotherthandescribedinthisspecification;and

X1.2.5Requireddocumentation,ifotherthantheminimumrequiredbythisspecification.

X1.3GradesofStainlessSteel—Differenttypesofstainlesssteelareselectedonabasisofpropertiesrequired,forexample,corrosionresistanceanddesigncriteria,andfabricationre-quirements.TableX1.1isacompilationthatservesasaguidefortheselectionofpassivationtreatmentfordifferentgrades,butisfarfromcompleteeitheringradesorinpassivationtreatments.

X1.4CleanWater—Cleanwaterisdefinedaswatercon-tainingamaximumtotalsolidcontentof200ppm.Rinsingcanbeaccomplishedbyacombinationofstagnant,countercurrentorsprayrinses,orboth,priortofinalrinse.

X1.5ChemicallyCleanSurface—Achemicallycleansur-faceisdefinedasasurfaceuponwhichwater,whenappliedmomentarilytothesurface,willremainonthatsurfaceinaneven,continuousfilm,andinadditionisfreeofanyforeignmaterialorresidualfilmdepositwhichwouldbedetrimentaltothequalityofthepart.

FIG.X1.1RecommendedNitricAcidPassivationTreatmentsforDifferentGradesofStainlessSteel

X1.6TestSpecimens—Whenusingtestspecimensinsteadofparts,thespecimenscaneffectivelyrepresentthepartsonlyiftheyhavebeenexposedtothesameprocessingsteps,suchasmachining,grinding,heattreating,welding,andsoforth,asthepartstheyaretorepresent.

X1.7CarburizedSurfaces—Stainlesssteelpartswithcar-burizedsurfacescannotbepassivatedbecausethecarboncombineswiththechromiumformingchromiumcarbidesonthesurface.

X1.8NitridedSurfaces—Stainlesssteelpartswithnitridedsurfacesshouldnotbepassivatedbecausethetreatmentwillseverelycorrodethenitridedcase.

X1.9ThisspecificationprovidesforthesamepassivationtreatmentsasFed.Spec.QQ-P-35C,butalsoincludesanumberofalternativepassivationtreatments.Theeffectivenessofanypassivationtreatmentisdemonstratedbythepartsmeetingthespecifiedtestingrequirementsaftertreatment.X1.10MartensiticGrade440C—High-strengthgradessuchas440Caresubjecttohydrogenembrittlementorintergranularattackwhenexposedtoacids.Cleaningbymechanicalmethodsorotherchemicalmethodsisrecom-mended.

X1.11Thesaltspraytestistypicallyusedtoevaluateausteniticstainlesssteelsandmaynotbeapplicabletoallmartensiticorferriticstainlesssteels.

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