ASTM F1940-2007a 电镀或涂覆紧固件中防氢脆的过程控制检定用标准试验方法

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【英文标准名称】:StandardTestMethodforProcessControlVerificationtoPreventHydrogenEmbrittlementinPlatedorCoatedFasteners
【原文标准名称】:电镀或涂覆紧固件中防氢脆的过程控制检定用标准试验方法
【标准号】:ASTMF1940-2007a
【标准状态】:现行
【国别】:
【发布日期】:2007
【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】:F16.93
【标准类型】:(TestMethod)
【标准水平】:()
【中文主题词】:涂层;脆裂;紧固件;氢脆;钢;试验方法;极限
【英文主题词】:coating;delayedfailure;displacementcontrol;EHE;fasteners;hydrogenembrittlement;IHE;incrementalstepload;loadingrate;plating;steel;threshold
【摘要】:Thistestmethodestablishesameanstoverifytheprevention,totheextentpossible,ofIHEinsteelfastenersduringmanufacturebymaintainingstrictcontrolsduringproductionoperationssuchassurfacepreparation,pretreatments,andplatingorcoating.Itisintendedtobeusedasaqualificationtestforneworrevisedplatingorcoatingprocessesandasaperiodicinspectionauditforthecontrolofaplatingorcoatingprocess.PassingthistestallowsfastenerstobestressedintensiontotheminimumspecifiedtensileloadinairwithalmostnopossibilityoftimedelayedfractureinairasaresultofIHEfromprocessing.Iftheamountofresidualhydrogenisnotsufficienttoinducecrackingorfractureinthespecimenunderworstcaseconditions,thenitcanbeconcludedthatallofthelotsoffastenersprocessedduringthatperiodwillnothavesufficientresidualhydrogenfromprocessingtoinducehydrogenembrittlementofthefastenersunderstressinairiftheprocessremainsincontrol,unchangedandstable.IfcertifiedspecimenswithdemonstratedsensitivitytoIHE,processedwiththefasteners,haveathresholdx2265;75%oftheincrementalsteploadnotchedbendfracturestress,NFS(B)F1624,itisassumedthatallfastenersprocessedthesamewayduringtheperiodwillalsopassanysustainedloadIHEtest.FIG.1DimensionalRequirementsfora0.4W-NotchedSquareBarBendSpecimen1.1Thistestmethodcoversaproceduretoprevent,totheextentpossible,internalhydrogenembrittlement(IHE)offastenersbymonitoringtheplatingorcoatingprocess,suchasthosedescribedinSpecificationsF1137andF1941.Theprocessisquantitativelymonitoredonaperiodicbasiswithaminimumnumberofspecimensascomparedtoqualifyingeachlotoffastenersbeingplatedorcoated.Trendanalysisisusedtoensurequalityascomparedtostatisticalsamplinganalysisofeachlotoffasteners.ThistestmethodconsistsofamechanicaltestfortheevaluationandcontrolofthepotentialforIHEthatmayarisefromvarioussourcesofhydrogeninaplatingorcoatingprocess.1.2Thistestmethodconsistsofamechanicaltest,conductedonastandardspecimenusedasawitness,fortheevaluationandcontrolofthepotentialforIHEthatmayarisefromvarioussourcesofhydrogeninaplatingorcoatingprocess.1.3Thistestmethodislimitedtoevaluatinghydrogeninducedembrittlementdueonlytoprocessing(IHE)andnotduetoenvironmentalexposure(EHE,seeTestMethodF1624).1.4ThistestmethodisnotintendedtomeasuretherelativesusceptibilityofsteelstoeitherIHEorEHE.1.5Thistestmethodislimitedtoevaluatingprocessesusedforplatingorcoatingferrousfasteners.1.6ThistestmethodusesanotchedsquarebarspecimenthatconformstoTestMethodF519,Type1e,exceptthattheradiusisincreasedtoaccommodatethedepositionofalargerrangeofplatingsandcoatings.ForthebackgroundonTestMethodF519testing,seepublicationsASTMSTP543andASTMSTP962.ThestressconcentrationfactorisataKt=3.10.2.Thesensitivityisdemonstratedwithaconstantimposedcathodicpotentialtocontroltheamountofhydrogen.Boththesensitivityandthebaselineforresidualhydrogenwillbeestablishedwithtestsonbaremetalspecimensinair.1.7ThesensitivityofeachlotofspecimenstoIHEshallbedemonstrated.AspecimenmadeofAISIE4340steelheattreatedtoahardnessrangeof50to52HRCisusedtoproducea"worstcase"conditionandmaximizesensitivitytoIHE.1.8Thetestisanaccelerated(24h)testmethodtomeasurethethresholdforhydrogenstresscracking,andi......
【中国标准分类号】:J13
【国际标准分类号】:21_060_01
【页数】:9P.;A4
【正文语种】: