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HardnessTraining-BasicsMethods,application,productsErhardReimann,ZwickGmbH&Co.KGHardnesstrainingatSDL–Shanghai,May2005Basics,standards,methods,relatedproducts Introductionintohardnesstestmethods,(dis-)advantages&applications 1.1 DefinitionofHardness 1.2 HardnessTestingofMetals Rockwell,Vickers,Knoop,Brinell,Martenshardness(universalhardness testing) 1.3 HardnessTestingofPlasticsandRubber Ballindentation,Shore,IRHD,Rockwell Terminologydefinition:“Hardnessistheresistancethatabodyofferstoindentationbyanother(hard)body”.[Martens,1900]Thetechnicalhardnessisamechanicalquantityfordescribingamaterialorthestateofamaterial.Thehardnesscannotbemeasureddirectly,itmustbederivedfromprimarymeasurementquantities(e.g.testload,indentationdepth,indentationarea).Hardnessvaluescanonlybecomparediftheyhavebeendeterminedviathesametestmethodwithidenticaltestparameters.Anexplicithardnessvaluecanonlybecharacterisedviathefollowingcriteria: •definitionofthehardnessvalue •indentorgeometryandmaterial, •sizeandindentationdurationattestload,aswellas thetypeofloading, •stateandsurfacequalityofthespecimen.Thefollowingisattheforefrontforselectionofahardnesstestmethod: •economy, •timeforspecimenpreparation, •availabilityofmachinesanddevices.basics–overview,methodsBasics,Standards,Methods,relatedproducts Introductionintohardnesstestmethods,(dis-)advantages&applications 1.1 DefinitionofHardness 1.2 HardnessTestingofMetals Rockwell,Vickers,Knoop,Brinell,Martenshardness(universal hardnesstesting) 1.3 HardnessTestingofPlasticsandRubber Ballindentation,Shore,IRHD,RockwellagendaMainlymethodswithstaticforceapplicationareusedformetals.Theindentor(ball,cone,pyramid)madeofsteel,hardmetalordiamondispressedintothesurfaceofthespecimenwhichisplacedonahardandfixedbase.Thetestloadisappliedbumplesslywithadefinedapplicationtimeandduration.Theindentationismeasuredafterloadremovalformanytestmethods.hardnesstestingofmetalsRockwell-overviewHardnessTestingaccordingRockwell(HR)depthmeasurement,DINENISO6508-1Scales-RockwellScaleoverview–RockwellhardnessIndenterPre-Load[N]TotalLoad[N]Anpplicationrange-RockwellApplicationrange120°-Diamond1/16“–Ball1/8“–Ball120°-Diamond1/16“–BallHardnessrangeHardnessIndentationdepth1UnitCalculationofinHV30 Min.Max.Max.Min.HardnessRockwell–applicationexamplesRockwell–tipsTipsforRockwell(HR…):1HR…-Unitmeans2or1µmindentationdepthnodisplacementofspecimenduringtestingproperspecimensupport,noburrnodirt(specimen,diamond)preventdiamondofdamageregardcorrect„choice“ofscaleregardminimumthickness(indentationdepth1/10or1/15) noimprintonsupportsurfaceregardminimumdistance(~5mm)noshocks,vibrations,strikesRockwell–productoverviewZwickZHR-ReiheZwickZHU250ZwickZHU187,5ZwickZHU0.2/Z2.5ZwickZHU2.5/Z2.5Zwick3106Vickers-overviewHardnessTestingaccordingVickers(HV)opticalindentationmeasurement,DINENISO6507-1,DINISO4516Vickers–tipsTipsforVickers(HV…):noshocks,vibration,strikescontactdiamond-specimenwithoutshockuseatleastpolishedsurfacestakeanappropriatemagnificationminimisemeas.errorshorizontalspecimensupport,nodirt(specimen,diamond)preventdiamondofdamagetakeanappropriateloadregardminimumthickness(indentationdepth1/10or1,5*d)regardminimumdistance(~3*d)takecareofloaddependencyofVickersVickers–products,overviewZwickZHV1mZwickZHV2mZwickZHU250ZwickZHU187,5ZwickZHU0.2/Z2.5ZwickZHU2.5/Z2.5ZwickZHV10AZwickZHV10PCZwickproductsforVickershardnesstestingZwickZHV20/Z2.5ZwickZHV30/Z2.5Knoop-overviewHardnessTestingaccordingKnoop(HK)opticalindentationmeasurement,ISO4545,DINISO4516Knoop–advantagesadvantages:Knoop(HK)suitableforsmallspecimenowingtothehighdiagonallengthratioofapprox.7:1betterthanVickersforthinspecimenorlayersastheindentationisnotsodeep(bythefactor4)butthediagonallengthsarethesamesuitableforbrittlematerialsowingtothelowsusceptibilitytocrackingnoinfluenceonthefunctionalityofthetestsurfaceowingtotheshallowtestindentationsKnoop–disadvantagesdisadvantages:Knoop(HK)timeconsumingtoachieveasufficientlyfinetestareasensitivityofthediamondindentortodamagetimeconsumingalignmentofthetestsurfacetoachievesymmetricaltestindentationsKnoop–products,overviewZwickproductsforKnoophardnesstestingZwickZHV1mZwickZHV2mZwickZHU250ZwickZHU2.5/Z2.5ZwickZHU0.2/Z2.5ZwickZHV10AZwickZHV10PCZwickZHV20/Z2.5ZwickZHV30/Z2.5Brinell–overviewHardnessTestingaccordingBrinell(HB)opticalindentationmeasurement,DINENISO6506-1185x–Object.90x–Objective45x–Objective15x–ObjectiveApplicationrange-BrinellApplicationrange–BrinellhardnessBrinell–tipsTipsforBrinell(HV…):noshocks,vibration,strikescontacthard-metallball-specimenwithoutshockuseatleastdressedtosizesurfacestakeanappropriatemagnificationminimisemeas.errorshorizontalspecimensupportwithoutspecimenmovenodirt(specimen,diamond)taketheloadingdegreeof10or30regardminimumthickness(1,33*d) noimprintonsupportsurfaceregardminimumdistance(~3*d)Brinell–productoverviewZwickZHU250ZwickZHU187,5ZwickZHU0.2/Z2.5ZwickZHU2.5/Z2.5ZwickZHV10AZwickZHV10PCZwickZHV20/Z2.5ZwickZHV30/Z2.5Martens–overview(I)HardnessTestingaccordingMartens(HM,HU)depthmeasurement,DINENISO14577-1StructureofDINENISO14577DINENISO14577(2003-05):Metallicmaterials-InstrumentedindentationtestfordeterminationofhardnessandothermaterialparametersPart1:TestprocedureMacro(F>2N;h>6µm),Micro,Nano(h<200nm)DifferentgeometriesofindentersPart2:VerificationandcalibrationofthetestingmachineDirect&indirectverificationPart3:CalibrationofreferencematerialsExamplesContentofDINENISO14577-1DINENISO14577-Part1:TestprocedureA:MaterialparameterHM,HMS,HIT,EIT,CIT,RIT,indentationworkB:TypesofcontrolC1:ComplianceofmachineC2:Areacorrectionforindenter(h<6µm)D:DiamondindenterE:InfluenceofsurfaceroughnessF:TheoreticalcorrelationtoVickershardnessLoad.-&unload.curvesEvaluationoftheloadingandunloadingcurvesSomecharacteristics:-Wplast,Welast-HM=f(Fmax,hmax)-HMs=f(sqrt(loadingc.))-HUplast=f(Fmax,hr)-HMit=f(Fmax,hmin)-.....loadingunloadingMartenshardnessIndentationhardnessMaterialparameterofMartenshardnessHM–evaluationMartens–1ScaleHM-ScaleDINENISO14577Materialsconventionalmethods Theinstrumentedindentationtestdeliversmaterial-independentcomparablehardnessnumbers.Martens–tipsTipsforMartens(HM…):noshocks,vibrations,strikescontactdiamond-specimenwithoutshockuseatleastpolishedsurfaceshorizontalspecimensupport,nodirt(specimendiamondt)preventdiamondofdamagechooseanappropriateloadregardminimundistanceand-thickness(indent.depth1/10)indentationdepth≥20xmeanroughnessvalueidealareageometryforh≥10µmsufficientMartens–productoverviewZwickZHU0.2/Z2.5ZwickZHU2.5/Z2.5ZwickproductsforMartenshardnesstestingreboundhardnesstesting-overviewHardnessTestingtoLeeb(HL)rebounddynamicmethod/measurementofenergy,ASTMA956Rückprallhärteprüfung–advantages,disadvantageadvantages:reboundhardnesstesting(Leeb,HL)extremelyshorttesttimesautomatictestsequencetestsinallpositions,e.g.alsooverheadmeasurementbyusingcorrectionfactorssimplehandlingportabledevicedirectdisplayofthehardnessvaluedisadvantage:testofspecimenthatarethinoroflowmassisproblematicLeeb–products,overviewIndentecReboundtesterZwickDynaPocket,patentedBasics,Standards,Methods,relatedproducts Introductionintohardnesstestmethods,(dis-)advantages&applications 1.1 DefinitionofHardness 1.2 HardnessTestingofMetals Rockwell,Vickers,Knoop,Brinell,Martenshardness(universal hardnesstesting) 1.3 HardnessTestingofPlasticsandRubber Ballindentation,Shore,IRHD,Rockwellagendahardnesstestingofplatics,rubber(I)Thehardnessofplasticscan,inprinciple,bedeterminedwiththemethodsofthemetalshardnesstesting.However,thehardnesstestmethodsballindentationhardness,ShoreA/DhardnessaswellasIRHDhardnessandRockwellhardness(scaleR...K,α)haveproventobethepreferredmethods.Thereasonsforthisare,ontheonehand,thequiteoftenstronglypronounced,timedependentmaterialbehaviourofpolymermaterials,and,ontheotherhand,thelowcontrastratiooftheplasticindentationtothesurface.Theappliedtestmethodsthereforeusuallyincludeameasurementoftheindentationdepthundertestloadandadefinedholdtime.hardnesstestingofplatics,rubber(II)ballindentationhardness-overviewHardnessTestingaccordingballindentation(H)depthmeasurement,DINENISO2039-1ballindentationhardness–advantagesadvantages:ballindentationhardness(H)suitableforhardnesstestsevenunderroughconditionsowingtotherelativelylargeindentations,suitablefortestingthehardnessofinhomogeneousand/oranisotropi-calmaterialssuitableforhardnesstestsonlargefinishedpartssimpleandrobustindentorcapabilityofbeingrationalisedorautomatedbythetestsequenceandevaluationinthesenseofonlinedataprocessingballindentationhardness–disadvantagesdisadvantages:ballindentationhardness(H)limitationwhentestingsmallspecimenowingtonecessarydistance(s)(≥10mm)betweenthetestindentations,aswellasthespecimenedgelimitingtheapplicationalrange,especiallyatlowhardness;theleastpossiblehardnesstobedeterminedaccordingtoteststandardisH49/30=8,5N/mm²(correspondsto,forexample,thehardnessofsoftPVCwithapprox.25-27%DOPasplasticizer)nocalibratedhardnesscomparisonplatesareavailableballindentationhardnessH–products,overviewZwickZHU250ZwickZHU0.2/Z2.5ZwickZHU2.5/Z2.5ZwickZHU0.2/Z2.5ZwickZHU2.5/Z2.5Zwick3106Shore–overviewHardnessTestingaccordingShorehardnessdepthmeasurement,DIN53505,ASTMD2240,ISO868Shore–advantagesadvantages:Shoremethodofhardnesstestsonelastomersusedworldwidesmalltesters,simplearrangementresultinginlowcostdevicessimpleoperationcanbeusedinalaboratorywithateststandanddefinedloadapplicationpressure,andcanalsobeusedonsitebypressingthetesterverticallyontothespecimenbyhandtestsonspecimenorcomponentsarepossibleindependentofgravity,even“overhead”oronverticalsurfacesgoodrepeatabilityandcompareabiltyofthemethodcapabilityofbeingrationalisedorautomatedbythetestsequence(indentationdepthmeasurement)andevaluationinthesenseofonlinedataprocessingShore–disadvantagesdisadvantages:ShoretestsonsmallpartssuchasO-ringsarenotpossiblefracturedsurfacesleadtogreatertestdatascatterspecimenofthickness<2mmcannotbetestedaccordingtostandardnocalibratedhardnesscomparisonplatesareavailabletestingwithoutateststandisrelativelyunexactShore–products,overviewZwickShore+teststandZwickproductsforShorehardnesstestingZwick311xShore,analogueZwick3105Shore/IRHDfully-automatedZwickShoredigitalIRHD–overviewHardnessTestingacc.IRHD(InternationalRubberHardnessDegree)depthmeasurement,DIN53519-2,ISO48,ASTMD1415IRHD–advantagesadvantages:IRHDbetterreproducibletestareachievedonconcaveorconvexsurfacesthanwithShoreAhardnessteststheIRHDmicromethodcanbeusedforsmallproductsorforproductswithdimensionsofthicknessordiameterdownto1mm(e.g.O-rings)indentationdepthchangesowingtorelaxationorcreepproceduresatthetimeoftestdatarecordingarerelativelysmall,thisiscausedbythelongloadapplicationdurationascomparedtothatforShoreA(applicationduration3s)Shore–disadvantagesdisadvantages:IRHDtestloadgenerationviaweightsorlowloadapplicationmaycausevibrations,whichinturncauseaccelerationtotheloadapplication;useasuitabledampingsystemnostandardisedprocedureavailableforindirect,i.e.includingallofthedevice’scomponents,monitoringofthehardnesstesterviahardnesscomparisonplatesnocalibratedhardnesscomparisonplatesavailableforplasticsShore,IRHD–applicationareasIRHD–products,overviewZwick3103Micro-IRHDZwick3105Shore/IRHDvollautomatischerHärteprüferRockwell(plastics)–overviewHardnessTestingaccordingRockwell(HR)depthmeasurement,scales:R,L,M,E,K,α,ASTMD785Rockwell(plastics)–advantagesadvantages:Rockwellcoversalargematerialrange(hardnessrange);agreaterhardnessrangecanbecoveredthroughvariantswithdifferentballdiametersandtestloadssuitableforhardnesstestingevenunderunsuitableconditionsdevicesforhardnesstestsonmetalscanbeusedinprincipletheonlystandardised“ballindentation”hardnesstestmethodthatrecordssolelytheremainingdeformationportionRockwell(plastics)–disadvantagesdisadvantages:RockwellnocomparisonoftestresultsthathavebeengainedthroughdifferentscalesthemethodsarelittleusedincomparisontoothersRockwell–productoverviewZwickZHR-LKPZwickZHU250ZwickZHU2.5/Z2.5Zwick3106