外文文獻翻譯-對鑄件缺陷位置和尺寸的無損檢測方法的評價

1、附錄三附錄三外文文獻原文及譯文外文文獻原文及譯文原文：AnevaluationofNDTmethodsfthelocationsizingoffgingdiscontinuitiesIninganNDTmethodfflawdetectioninfgingsanumberofvariablesmustbeconsidered:a)thetypeofdiscontinuitytobeassessedb)themethodtobeusedf

2、detectionevaluationc)thevariablesassociatedwiththefgingitselfThevariablesinitema)willgovernthelocationwithinthefgingitsientationwithrespecttoaparticularsurfaceItemb)couldincludeaconsiderablearrayofNDTmethodsbutfthepurpos

3、eofthispaperonlythesixmostwidelyusedareconsidered一visualtesting(VT)perantinspection(PI)magicparticleinspection(MI)eddycurrenttesting(ET)radiographicinspection(RT)ultrasonicinspection(UI).Inthelastitemc)thecomponentracein

4、cludesuchthingsasconditiongeometryaccessfinspection.a)FgingdiscontinuitiesThelocationofthediscontinuitywillhaveasignificantinfluenceontheionoftheNDTmethodtobeusedtheyaretherefegroupedintothreecategiestoaidthision:1.opent

5、othesurface:lapsseamburstslugscracksinclusions2.slightlysubsurface:seamstringersinclusionsgrainstructurevariations3.internal:stringersburstlaminationgrainstructureinclusionspipingAbriefreviewofthesetermsmaybehelpful:Lap:

6、foldedmetalflattenedintothesurfacebutnotfusingwithitSeam:linearflawsduetooxidizedblowholesingotsplasheswhichareelongatedbyhotwkingBurst:rupturescausedbyfailureofplasticdefmationbyprocessingattoolowatemperatureexcessivewk

7、ingofmetalStringers:abarstockdefectduetononmetallicinclusionsbeingsqueezedoutintolongthinstringsLamination:planardefectalignedparalleltosurfaceiginatingintheiginalingotfromrolledoutpipingCracks:transgranularfailureduetol

8、ocalizedstressesresultingfromnonunifmheatingcoolingnonplasticdefmationInclusions:impuritiessuchasslagoxidesulphidesoftenfromtheiginalmoltenstageinfmingthebilletusedffgingtotalbeingimpedance.Thisimpedancealsocausesalagbet

9、weenthecurrentthevoltagecalledaphaseshift.Thisshiftimpedanceareacteristicsofthecoil.Ifthecoilisnowplacedclosetoaconductingsurfacethereversingmagicfieldinducesareversingcurrentintheconducting(eddycurrent)whichopposesthein

10、ducingfield.Thisoppositionalterstheimpedanceofthecoilasuitableinstrumentcandetectthesechanges(bothphaseangleimpedance).Fagivendiscontinuityfreesurfaceaspecificalterationwillbepresentwhichcanbezeroed.Ifthecoilnowpassesove

11、radiscontinuityachangeininductionwilloccurwhichwillberegisteredbytheinstrument.Howeverachangeintheconductivityofthematerialwillalsoeffecttheinductionaswillchangesinpermeability.Thusnonunifmheattreatmentsegregationinhomog

12、eneitiesinmaterialcompositionstructurewillalsoeffecttheinductioncreatean‘indication’.Anothercriticalfactisthedistancebetweenthecoilthetestsurface.This‘liftoff’canbeusedinapositivewaytodeterminecoatingpaintthickness’oncon

13、ductingmaterials.Butequallydifferencesinthecoilspecimengapcanresultinnonrelevantsignals.Thesystemcantherefedetectsurfaceslightsubsurfacediscontinuities.Howeverthisisonlypossibleinconductingmaterialstheproximityofthetestc

14、oiltothetestsurfaceiscritical.Thismeansthatfanycomponent(otherthanflatplate)specialprobesareusuallydesignedtofollowspecificcomponentcontours.Asmalleddycurrentmachinecancostaslittleas$2000butalargeautomatedmachinecancostu

15、pto$20000RT一Shtwavelengthelectromagicradiationwillpassthroughmanymaterialsdependingupondensitythicknessthencreatearangeofexposuresoneitherfilmafluoscopicscreentopresentavisualimageoftheinternalcompositionoftheitem.Differ

16、encesinabsptionwithinthematerialduetosuchthingsasgasholescracksburstswillcreatephotographicdensitydifferencesonthefilmdetectwhichcanbeinterpretedbytrainedpersonnel.ThesourceofradiationcanbeanXraytubeagammasource(suchasIr

17、idiumCobalt)theimagescanbegeneratedoneitherfilmasrealtimeimagesonfluoscopicscreens.Defectientationisavitalfactinradiographysinceitisthicknessdifferenceswhichtheprocessdetects.Hencealaminationtypedefectparalleltothefilmwo

18、uldbealmostimpossibletodetect.Ontheotherhacrackperpendiculartothefilmwouldalmostcertainlybedetected.Itistherefeoftenthecasethatasinglecomponentwouldhavetoberadiographedfrommethanonedirectionindertodetectmostdefects.Final

19、lytheradiationusedishighlyhazardoustherefeanyenvironmentinwhichitisusedmustsuitablyshieldedtopreventexposureoftheoperat.AswellasshieldingtheuseofXgammarayswillalsorequiremonitsalarmsinterlockspersonaldosimetrysystemswhic

20、halongwiththefilmitselfaddstothecost.AbasicXraysetupwouldcostaround$10000withancillaryequipmentfilmcouldcost$3000peryeartorun.UT—Ataninterfacebetweenmaterialsofdifferingacousticimpedanceasoundwavewillhaveaproptionreflect