维氏硬度和洛氏硬度.ppt

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1、HardnessTest陈政01441390012015.5.14Twoparts:1.VickersHardnessTest(维氏硬度)2.Rockwellhardnesstest（洛氏硬度）VickersHardnessTesthasfairlywideacceptanceforresearchwork,5-1500DPHalsonameddiamond-pyramidhardnessIndenter:asquare-basediamondpyramid(方锥形金刚石)Angle:136︒thed

2、iamond-pyramidhardnessnumber(DPH)Definition:theloaddividedbythesurfaceareaoftheindentation(压痕)Equation:Where,P=appliedload,kgL=averagelengthofdiagonals,mm——microscopeθ=anglebetweenoppositefacesofdiamond=136︒AdvantagesandDisadvantagesAdvantages:1.provide

3、acontinuousscaleofhardness*，5-15002.DPHisindependentofload.*Disadvantages:1.itisslowandneedmoretime2.requirecarefulsurfacepreparationofspecimen3.greaterchanceforpersonalerrorinthedeterminationofthediagonallengthIndentationtypesTherearethreekindsofdiamon

4、d-pyramidindentations:a)perfectindentationb)pincushionindentation(枕形压痕)c)barreledindentation（桶状压痕）PerfectIndentationmadewithaperfectdiamondindentersquarebutisjustideal.PincushionIndentationReason:sinkinginofthemetalObjects:annealedmetals（退火金属）Result:ano

5、verestimateofthediagonallengthandDPHislowerBarreledIndentationReason:ridgingorpilingupofthemetalObjects:cold-workedmetalsResult:alowvalueofthecontactareasotheDPHishigherRockwellhardnesstestThemostwidelyusedhardnessamongthethreemethods.Whyisitmostwidelyu

6、sed?1.speedisfast2.fewpersonalerrors3.distinguishsmallhardnessdifferences4.indentationissmallandtestedwithoutdamage5.reproducible(可重复的)TestStepsUsethedepthofindentationtoexpressthehardness,thestepsare:1.applyminorload(初始小载荷)——10kg2.applymajorload——60,10

7、0,150kg3.UnloadthemajorloadPurposeofminorload1.seatthespecimen2.minimizetheamountofsurfacepreparation3.reduceridgingorsinkinginIntroductionofadialgagecontains100divisionseachdivision——0.002mmreversed：smallpenetration—highhardnessnumberpurelyarbitrary(no

8、n-dimensional)Introductionofthetestdevicetotal9scales——combinationsof3typesofindentersand3differentloadsBraleindenter(120︒)3typesofindenters1.6mm-diametersteelball3.2mm-diametersteelball60kg3differentloads100kg150kgScaleTypeAppli