Designation:B721–91(Reapproved1999)StandardTestMethodforMicrohardnessandCaseDepthofPowderMetallurgy(P/M)Parts1ThisstandardisissuedunderthefixeddesignationB721;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(e)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thistestmethodcoversdeterminationofthemicrohard-nessofpowdermetallurgy(P/M)partsandapplicationsofmicrohardnesstestresultstomethodsfordeterminationofthecasedepth.TechniqueformeasurementofcasedepthofP/Mpartsbyobservationisalsooutlined.1.2PartA:MicrohardnessMeasurement—ThisprocedurecoverstestmethodstodeterminethemicrohardnessofP/MpartswiththeKnoop(HK)ortheVickers(HV)indenters.ProceduresforsurfacepreparationoftheP/Mmaterialpriortomicrohardnessmeasurementareincluded.1.3PartB:CaseDepthMeasurement—ProceduresandmethodsfordeterminationofbotheffectivecasedepthandobservedcasedepthforP/Mpartsareincluded.TheprinciplesofPartAonMicrohardnessMeasurementareutilizedtomeasurecasedepth.1.4Thevaluesstatedininch-poundunitsaretoberegardedasthestandard.Thevaluesinparenthesesareforinformationonly.1.5Thisstandarddoesnotpurporttoaddressthesafetyconcerns,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappropriatesafetyandhealthpracticesanddeterminetheapplicabilityofregulatorylimitationspriortouse.2.ReferencedDocuments2.1ASTMStandards:B243TerminologyofPowderMetallurgy2E384TestMethodforMicrohardnessofMaterials33.Terminology3.1Definitionsofpowdermetallurgy(P/M)termscanbefoundinTerminologyB243.Additionaldescriptiveinforma-tionisavailableintheRelatedMaterialsectionofVol.02.05oftheAnnualBookofASTMStandards.4.SummaryofTestMethod4.1PartA:Microhardnessismeasuredbyusingacalibratedmachinetoforceadiamondindenterofspecificgeometry,underaknowntestload,intothesurfaceofthetestmaterial.4.1.1Ordinarily,theimpressionoftheindenterismeasuredopticallyandcorre...
