Common Rules for Casting Design

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1、CASTINGTECIINOLOGYANDCASTALLOYSFormerlyProfessorMetallurgicalandMaterialsEngineeringDepartmentIndianInstituteofTechnologyKharagpurPrentice..HallofIndia[l'iiilII"I';;/iII.iilr;ii'lli~~G~@JNewDelhi-1100012005CommonRulesforCastingDesignThephysicalandmechanicalpropertiesofcastalloysinfluencecasting

2、-designtoaconsiderableextent.Beforediscussingthecommondesignrules,itwouldbeappropriatetoreviewtherelevanceofthesecharacteristics[1].DatarelatedtothephysicalcharacteristicsofcommonfoundryalloysaregiveninTable5.1.Thephysicalpropertiesofimportanceare:•Fluidlife•Solidificationshrinkage•Type(eutectic

3、,directionalandequiaxed)•Volume(small,mediumandlarge)•SlaglDrossformationtendencySimilarlytheimportantmechanicalpropertiesare:•Modulusofelasticity(thestiffnessofthealloyitself)•Sectionmodulus(thestiffnessofthecastinggeometry)Thesecharacteristicsarediscussedbelowinfurtherdetails.Fluidlife(i.e.flu

4、idity)affectsthedesigncharacteristicsofacasting,suchastheminimumsectionthicknessthatcanbecastreliably,themaximumlengthofathinsection,thefinenessofcosmeticdetails(likeletteringandlogos)andtheaccuracywithwhichthealloyfillsthemouldextremities.AlloyGroupFERROUSGreyironExcellentEutectictypeVerysmall1

5、371-1427LittleDuctileironGoodEutecticSmall1371-1427°CSomedirectionalCarbonandLargelowalloysteelHighalloysteelsNONFERROUSAluminium356ExcellentEutectictypeLittle704-760°CModerateAluminium206Fair/GoodEquiaxedModerate/Large.704-760°CLargeAluminiumFairEquiaxedModerate/Large1093-117rcLargebronzeSilico

6、nbronzeFairEutectictypeLittIe1038-1121°CLargeMagnesiumExcellentDirectionalModerate1300-1400°FLittle/ZE43(704-760°C)ModerateYellowbrassPoor/FairEutectictypeModerate982-1066°CLargeTitaniumVerygoodEutectictypeLittle1760-1816°CVerylargeZirconiumFairEutectictypeLittle1816-1871°CVerylargeSolidificatio

7、nShrinkageTherearethreedistinctstagesofshrinkageasmoltenmetalssolidify.Theseare-liquidshrinkage,liquid-to-solidshrinkageandsolidstateshrinkage.Liquidshrinkageisthecontractionoftheliquidmetalbeforesolidificationbegins;itisnot