PV 1113-EN-2023 AlMgSi变形合金 测试晶间腐蚀抗性

GroupstandardPV1113

Issue2023-07

Class.No.:53312

Descriptors:AlMgSi,aluminum,corrosion,intercrystallinecorrosion,wroughtalloy

AlMgSiWroughtAlloy

TestingtheResistancetoIntercrystallineCorrosion

Previousissues

PV1113:2007-10

Changes

ThefollowingchangeshavebeenmadetoPV1113:2007-10:

a)Standardrestructuredandupdated

b)

Section1„Scope“

updated

c)Prefaceand„Purposeofthetest“sectiondeleted;contentsdistributedto

section1

and

section3

d)

Figure1

added

e)

Section„Specimen

5.2preparation“:Finalpreparationstagechanged

f)

Section„Specimen

5.3evaluation“revised

g)

Section„Documentation

6ofresults“revised

h)

AppendixA„Example

imagesforcorrosion“added

Contents

Page

1

Scope

2

2

Designation

2

3

Generalinformation

2

4

Testmethod

2

4.1

Briefdescription

2

4.2

Specimens

2

4.2.1

Generalinformation

2

4.2.2

Taking

specimensamples

2

4.2.3

Preparation

ofspecimens

3

4.3

Testsolution

3

4.4

Testprocedure

3

5

Evaluation

4

5.1

Sampling

4

5.2

Specimenpreparation

4

Alwaysusethelatestversionofthisstandard.

Thiselectronicallygeneratedstandardisauthenticandvalidwithoutsignature.Acommaisusedasthedecimalsign.TheEnglishtranslationisbelievedtobeaccurate.Incaseofdiscrepancies,theGermanversioncontrols.

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VWNORM-2022-12

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5.3

Specimen

evaluation

4

6

Documentation

ofresults

5

AppendixA

Example

imagesforcorrosion

6

1Scope

Thisstandarddescribesacorrosiontestthatisperformedonaluminumwroughtalloys.Itisinten-dedtotestthesusceptibilitytocorrosioninareasclosetothegrainboundaries.

ThemethodisonlyapplicabletoAlMgSiwroughtalloysofthe6xxxserieswhicharedeliveredasrolled,forged,orextrudedproducts(finishedproductsandrawmaterials)andareusedinapplica-tionswithoutspecialsurfaceprotection.

2Designation

IntercrystallinecorrosionasperPV1113

3Generalinformation

Themethodalsoappliestoforgedorformedpartsthataremanufacturedfromextrudedrawmate-rial.Insuchparts,dependingonthelocalformingdegree,intercrystallinecorrosion(IC)orselec-tivecorrosion(SC)oftheinterdendriticareas(i.e.,corrosionalongthecastgrainboundaries)mayoccurinthistest.

NOTE1:

FigureA.1

to

Figure

A.3showexamplepicturesforthedifferenttypesofcorrosion.Thetestcanbeperformedinaquick,simple,andlow-costway.Thetestcanverifythematerialdecompositionthatwouldotherwiseoccuronlyafterseveralyearsofexposuretode-icingsalt.

4Testmethod

4.1Briefdescription

Specimensaretakenfromthepart,whicharedippedinatestsolutionfor2h(see

section4.3

).

Fromthesespecimens,microsectionsaregeneratedandthecorrosivedamageevaluatedunderalightmicroscope.

4.2

4.2.1

Specimens

Generalinformation

Thequantityandsamplinglocationofthesamplesmustbechosensuchthatvariousmanufactur-inginfluencesinthepartcanbetakenintoaccount(e.g.,differentformingdegrees,additionalcom-pressionsorelongations,anddifferentcrosssections).

Itmustbeensuredthattheentirepartcrosssectioniscovered(exceptforsheetmetalpanels).

4.2.2Takingspecimensamples

Whentakingsamplespecimens,heatingressanddeformationofthecuttingsurfacemustbeavoi-ded.

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4.2.3Preparationofspecimens

Grindallcutsurfacesofthespecimensusinganiron-freesandpaperoranabrasiveclothof220or240grainwithasuitablecoolant(e.g.,water).Thendegreasethewholespecimensurfacefor

1minwithacetoneinanultrasonicbathandsubsequentlycleanitfor1minwithalcoholinanultra-sonicbath.

Donotcleanthespecimeninanacidicoralkalinesolution,becauseespeciallyanalkalinemilieucancauseinitialcorrosion.

Thetakingofasamplespecimenisshownschematicallyin

figure1

,usingtheexampleofaforgedtrackcontrolarm.

Figure1-Processofspecimenpreparationforaforgedtrackcontrolarm

4.3Testsolution

Thetestsolutioniscomposedasfollows:

–1000mldemineralizedH2O

–20gNaCl(technicalpurity≥98%)

–100ml25%HCl

Thetemperatureofthetestsolutionmustbe(20±0,5)°Cduringtheentiretest.Atemperature-controlledwaterbathmustbeusedforthis,ifnecessary.

4.4Testprocedure

Ifthevolumeofthetestsolutionisatleast8mlpercm2ofthetotalspecimensurfacearea,severalspecimensofthesamealloyspecificationmaybetestedsimultaneously.

Placethespecimensonthebottomofabeakerinsuchawaythattheyarenottouching.Thetestsolutionmustfullycoverthespecimens.

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PV1113:2023-07

Leavethespecimensimmersedinthetestsolutionfor2hat(20±0,5)°Cwithoutinterruption.Re-movethespecimensfromthetestsolutionandrinsethemimmediatelyundercold,flowingtapwa-terfor1min.Thendrythemthoroughlyusingcompressedairorahairdryer.Donotuseanyme-chanicalaids(e.g.,brushesorultrasonicbath).

Usethetestsolutiononlyonetime.

5Evaluation

5.1Sampling

Takethemicrosectionspecimensfromthecorrosionspecimensinsuchawaythattheentirepartcrosssection(exceptforsheetmetalpanels)andthewholepartsectionsurfacearea(i.e.,thearti-ficiallyproducedlaboratorysurface)iscontained.Thisisshownschematicallyin

figure1

,usingtheexampleofaforgedtrackcontrolarm.

5.2Specimenpreparation

Embedthespecimensinsyntheticresin,inordertopreventthedamagedgrainsfrombreaking

away,totheextentpossible,whenpreparingthemicrosections.Usecoldorhotembedding.

Asthefinalmicrosectionpreparationstage,performachemo-mechanicalfinegrindingwithacol-loidalSiO2suspension(alkaline;e.g.,OP-S

1)

).Thismakesevenfinecorrosionspotsvisible,whichmighthavebeencoveredbypreviouspreparationsteps.

5.3Specimenevaluation

Evaluatethemicrosectionsunderalightmicroscope(100xto500xmagnification)within24hafterthetest.

Usethefollowingterminologytogradethecorrosionofthesurfaceandthepartsectionsurface:

NoIC:Ifthereisnocorrosion

2)

oronlysurfacecorrosionthatdoesnotextendbe-

yondthegrainboundaries

IsolatedIC:Ifonlyisolatedareaswithaffectedgrainsintheareaofthesurfaceorintheareaclosetothecenterofthepartsectionsurfacearepresent(see

figureA.4

)

FrequentIC:IflargerareasorfrequentareaswithICarepresentatthepartsurfaceandpartsectionsurface,thusenablingcrackpropagationtogreaterdepths

(see

figureA.5

)

CircumferentialIC:IftheaffectedzoneonthesurfaceencirclesthepartlikearibbonorthepartsectionsurfaceshowscontinuousIC(see

figureA.6

)

NOTE1:Theterm„IC“isalsousedhereforselectivecorrosion.

Besidesthefrequency,alsoevaluatethemaximumcorrosiondepths.Makeadistinctionbetweenthe"actualpartsurface"andthe"artificiallygeneratedlaboratorysurface"hereaswell.

1)OP-SistheproductdesignationbymanufacturerStruersS.A.S..

Thisinformationisonlyintendedforinformationalpurposesfortheusersofthisin-housestandard.Thisdoesnotsignifyanen-

dorsementofthementionedproductbytheVolkswagenGroup.Equivalentproductsmaybeusedifitcanbeverifiedthattheyleadtothesameresults.

2)Donotratecorrosionwithadepth≤25µm.

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