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冷挤压凸模的断裂失效分析.docx

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冷挤压凸模的断裂失效分析 Title:FailureAnalysisofColdExtrusionDies Introduction: Coldextrusionisacommonmethodusedinvariousindustriesforshapingmetalpartswithhighprecisionandmechanicalstrength.Thedieusedincoldextrusionplaysacriticalroleinmaintainingtheshapeandintegrityoftheextrudedworkpiece.However,thefailureofcoldextrusiondiescanleadtodisruptionsinproductionandcostlyrepairs.Thispaperaimstoanalyzethefracturefailureofcoldextrusiondiesanddiscussthepossiblecausesandpreventivemeasures. 1.FractureTypesinColdExtrusionDies: 1.1.DuctileFracture: Ductilefractureisacommonfailuremodeobservedincoldextrusiondies.Thistypeoffractureischaracterizedbyplasticdeformationbeforethecrackpropagates.Ittypicallyoccursinmaterialswithhighductility,suchasnonferrousmetalsorlow-carbonsteels.Ductilefractureiscausedbyexcessiveappliedforces,improperdiedesign,orinadequatediematerialstrength. 1.2.BrittleFracture: Brittlefractureoccurswithoutappreciableplasticdeformationpriortofailure.Itiscommonincoldextrusiondieswithhighcarbonortoolsteels.Thistypeoffracturecanbeattributedtofactorssuchasexcessivehardness,lowtoughness,andstressconcentrationcausedbydefectsordesignflawsinthedie. 2.CausesofFractureFailure: 2.1.FatigueFailure: Repeatedloadingandunloadingcyclesduringthecoldextrusionprocesscancausefatiguefailureinthedie.Thisisparticularlytruewhenthedieexperienceshighappliedstressesandstrainrates.Factorssuchasinadequatediedesign,improperheattreatment,andmaterialdefectscanacceleratethefatigueprocess,leadingtocrackinitiationandpropagation. 2.2.OverloadFailure: Excessiveappliedforcesbeyondthedie'sloadcapacitycanresultinoverloadfailure.Thiscanoccurduetofactorssuchasimproperdiedesign,incorrectmaterialselection,orunforeseenprocessvariations.Overloadfailureischaracterizedbysuddenfractureinitiationandrapidcrackpropagation. 2.3.ThermalFatigueFailure: Duringcoldextrusion,thediemayexperiencerapidheatingandcoolingcyclesduetothecontactwithhotworkpiecematerial.Thiscanresultinthermalfatiguefailure,asthedieexpandsandcontractsrepeatedly,ind