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【英文标准名称】:StandardTestMethodforLinear-ElasticPlane-StrainFractureToughnessKIcofMetallicMaterials
【原文标准名称】:金属材料的线性弹性平面变形断裂韧度KIc用标准试验方法
【标准号】:ASTME399-2009e2
【标准状态】:现行
【国别】:
【发布日期】:2009
【实施或试行日期】:
【发布单位】:美国材料与试验协会(US-ASTM)
【起草单位】:E08.07
【标准类型】:(TestMethod)
【标准水平】:()
【中文主题词】:半制成品;疲劳;金属和金属材料
【英文主题词】:Fabricatedmaterials;Fatigue;Metalsandmetallicmaterials
【摘要】:ThepropertyKIcdeterminedbythistestmethodcharacterizestheresistanceofamaterialtofractureinaneutralenvironmentinthepresenceofasharpcrackunderessentiallylinear-elasticstressandseveretensileconstraint,suchthat(1)thestateofstressnearthecrackfrontapproachestritensileplanestrain,and(2)thecrack-tipplasticzoneissmallcomparedtothecracksize,specimenthickness,andligamentaheadofthecrack.VariationinthevalueofKIccanbeexpectedwithintheallowablerangeofspecimenproportions,a/WandW/B.KIcmayalsobeexpectedtorisewithincreasingligamentsize.Notwithstandingthesevariations,however,KIcisbelievedtorepresentalowerlimitingvalueoffracturetoughness(for2%apparentcrackextension)intheenvironmentandatthespeedandtemperatureofthetest.LowervaluesofKIccanbeobtainedformaterialsthatfailbycleavagefracture;forexample,ferriticsteelsintheductile-to-brittletransitionregionorbelow,wherethecrackfrontlengthaffectsthemeasurementinastochasticmannerindependentofcrackfrontconstraint.ThepresenttestmethoddoesnotapplytosuchmaterialsandtheuserisreferredtoTestMethodE1921andE1820E1820.Likewisethistestmethoddoesnotapplytohightoughnessorhightearing-resistancematerialswhosefailureisaccompaniedbyappreciableamountsofplasticity.Guidanceontestingelastic-plasticmaterialsisgiveninTestMethodE1820.ThevalueofKIcobtainedbythistestmethodmaybeusedtoestimatetherelationbetweenfailurestressandcracksizeforamaterialinservicewhereintheconditionsofhighconstraintdescribedabovewouldbeexpected.BackgroundinformationconcerningthebasisfordevelopmentofthistestmethodintermsoflinearelasticfracturemechanicsmaybefoundinRefs(1)and(3).CyclicforcescancausecrackextensionatKIvalueslessthanKIc.Crackextensionundercyclicorsustainedforces(asbystresscorrosioncrackingorcreepcrackgrowth)canbeinfluencedbytemperatureandenvironment.Therefore,whenKIcisappliedtothedesignofservicecomponents,differencesbetweenlaboratorytestandfieldconditionsshallbeconsidered.Plane-strainfracturetoughnesstestingisunusualinthattherecanbenoadvanceassurancethatavalidKIcwillbedeterminedinaparticulartest.Therefore,compliancewiththespecifiedvaliditycriteriaofthistestmethodisessential.ResidualstressescanadverselyaffecttheindicatedKQandKIcvalues.Theeffectcanbeespeciallysignificantforspecimensremovedfromas-heattreatedorotherwisenon-stressrelievedstock,fromweldments,fromcomplexwroughtparts,orfrompartswithintentionallyinducedresidualstresses.Indicationsofresidualstressincludedistortionduringspecimenmachining,resultsthatarespecimenconfigurationdependent,andirregularfatigueprecrackgrowth(eitherexcessivecrackfrontcurvatureorout-of-planegrowth).GuideB9......
【中国标准分类号】:H22
【国际标准分类号】:77_040_10
【页数】:33P.;A4
【正文语种】: