VDG-P202-2010-Volume-Deficits-of-Castings

P202Version:September2010BDG-ReferenceSheetVDGSpecification©BUNDESVERBANDDERDEUTSCHENGIESSEREI-INDUSTRIE(BDG)Page1of24Tobeobtainedfrom:BDG-InformationszentrumGiesserei,Sohnstraße70,D-40237Düsseldorf,Tel.:[phone],Fax:-361,(Microporosity)22.1.2Hotcracks42.1.3Gasporosity42.2Otherflaws53Potentialeffectsofporosity63.1Staticstrength63.2Strengthundercyclicloading(dynamicstrength)63.3Generalleaktightnessandmatingsurfaces73.4Surfaceandheattreatment74Evaluatingtheporosityofcastings74.1Radiographictestwithimageintensifier(RT)84.2Ultrasonictest(UT)94.3Leaktightnesstest(LT)94.4Visualtest(VT)94.5Densitytest94.6Microsectiontestandsectiontest105Porosityevaluationbymeansofmicrosectiontesting,sectiontestingandquantitativeimageanalysis105.1ReferenceAreasfortheporeevaluation115.2Porositykey135.2.1Definitionandapplicationrecommendationforthereferencearearoughness[Rz]135.2.2Examplesofporositykeys166Drawingnotes166.1Collectivenote166.2Notesfordefinedareas177Literaturereferences,standards,guidelines18App.1Examplesofmicrostructureswithdifferentporecontents21App.2Exampleofreferenceareasandarrangementofpartialsurfaces/measuringfields22App.3Definitionofotherflaws24VolumeDeficitsofCastingsMadefromAluminium,Magnesium,andZincCastingAlloysReferenceSheetcompiledbyBDGTechnicalcommitteesHighPressureDieCastingandLightMetalCasting.CONTENTSOnlyappliestoEnglishtranslation:TheEnglishtranslationisbelievedtobeaccurate.Incaseofdiscrepancies,theGermanversionisaloneauthoritativeandcontrolling.©BUNDESVERBANDDERDEUTSCHENGIESSEREI-INDUSTRIE(BDG)Page2of24P202Version:September2010BDG-ReferenceSheetVDGSpecificationTobeobtainedfrom:BDG-InformationszentrumGiesserei,Sohnstraße70,D-40237Düsseldorf,Tel.:[phone],Fax:-361,(porosity).Otherflawssuchassinkmarks,coldflowmarks,stickmarks,drawmarks,burrs,andheatcheckpat-ternsarenotpartofthisguideline.Porositycanbeminimised,butnotprecluded,ifthedesignengineerandcastercollaborate.1.2ALLOYSThescopeofthisreferencesheetisrestrictedtocastingsmadeofaluminium,magnesium,andzinccast-ingalloysaccordingtotherelevantstandards(DINEN1753“Magnesium”,DINEN1706“Aluminium”,DINEN12844“Zinc”).1.3CASTINGPROCESSThecontentsofthisBDGreferencesheetrefertoDiecastingprocessesincludingrelatedspecialcastingprocesses,(e.g.,squeezecastingandSSM/thixocasting)Permanentmouldcastingprocessesandvariants(e.g.,low-pressurepermanentmouldcasting)SandcastingprocessesandvariantsInvestmentcastingprocesses2Explanatorynotes2.1VOLUMEDEFICITS2.1.1Shrinkagecavities(Microporosity)Shrinkagecavitiesresultfromthethermo-physicalpropertiesofthecastmaterialsduringsolidification.©BUNDESVERBANDDERDEUTSCHENGIESSEREI-INDUSTRIE(BDG)Page3of24P202Version:September2010BDG-ReferenceSheetVDGSpecificationTobeobtainedfrom:BDG-InformationszentrumGiesserei,Sohnstraße70,D-40237Düsseldorf,Tel.:[phone],Fax:-361,(=solidificationcontraction);seeFigure1.Becausetheoutershellandsprueofacastinggenerallysolidifyearly,volumedeficitscanformintheinteriorofthecasting.Bymeansofasuitabledesignofthecastingforsolidification,e.g.,avoidanceofharshdifferencesinthewallthickness,andoptimaldesignofthecastingsystem,thisvolumedeficitcanbeminimised.Shrinkagecavitieshaveamoreorlessfissured,caverntypeshape.Figure2:TypicalshapeofshrinkagecavitiesItisimpossibletomanufacturecastingsthatarecompletelyfreeofshrinkagecavities.Ts=meltingpointFigure1:SpecificvolumeofpurealuminiumasafunctionoftemperatureTSLiquidcontractionSolidcontractionSpecificvolume(cm3/g)Temperature(°C)Solidificationcontraction©BUNDESVERBANDDERDEUTSCHENGIESSEREI-INDUSTRIE(BDG)Page4of24P202Version:September2010BDG-ReferenceSheetVDGSpecificationTobeobtainedfrom:BDG-InformationszentrumGiesserei,Sohnstraße70,D-40237Düsseldorf,Tel.:[phone],Fax:-361,:fluidmechaniccauses(inclusionofairbubblesduetoturbulentmouldfilling)Process-relatedandmould-material-relatedcauses(outgassingbyreleaseagent,core/mouldmaterial,insufficientremovalofcastinggases)Thermodynamiccauses(solubilitylimitofgasesinthecastingalloyexceededduringcooling/solidification)Theirappearancediffersfromporosityduetoshrinkage.Puregaspores,iftheyare