一種大型齒輪組織缺陷及其開裂失效分析.pdf

1、大連海事大學(xué)碩士學(xué)位論文一種大型齒輪組織缺陷及其開裂失效分析姓名：李存杰申請(qǐng)學(xué)位級(jí)別：碩士專業(yè)：載運(yùn)工具運(yùn)用工程指導(dǎo)教師：于志偉20100601英文摘要ABSTRACTTwolargecarburizedgearscrackedwhengrindingteethandonastaticallyplacedstateInspectioninsiteshowthatforthetwogearsthecircumferentialcracki

2、ngOCCULTedonthespokeplatebetweenthetwoholesofgearThemacrostructureandmicrostructureofgearmaterialwereanalyzedbySEMandOPMindetailChemicalcompo—sitionofcoreandmicrocompositionwereexaminedbyOESandEDXMacroandmicrofractureswe

3、reinvestigatedbyvisualandSEMtodeterminethecrackingmechanismandthefailurecausesofthetwogearsThemainresultscanbeconcludedasfollows：(1)Severemacropoint—likesegregationispresentinthegearmaterialContentofSi，Mn，CrespeciallyP’S

4、inthesegregationzonesismuchhigherthaninthenon—segregationzonesTheexcessivealloyingelementsinthesegregationzoneresultinthemicrostructuredifferencebetweenthesegregationandnon—segregationzones(2)Thecracksinitiatedfromthelar

5、gersizesegregationzonesinthecoreofspokeplateofgearandpropagatedtowardthetwoholesurfacesonthespokeplateandtheupperandlowendsofgearFailureinintergranularmodeandtheintergranularfacetsassociatedwithductiletearingWasfoundEvid

6、encesindicatethatthefailureofthegearsisduetohydrogenembrittlementThepossiblesourceforhydrogenWasintroducedduringmeltingandcastingoperating(3)Thelargesegregationzonesinthecoreofspokeplateofgearsupplythefavorablemetallurgi

7、calconditionforhydrogen—inducedfracture：presenceofexcessiveimpuritiesofS，Pandmicrostructureofbainitesusceptibletohydrogenembrittlement，whichbecamethetrapofhydrogenAsthehydrogencontentinthesegregationzoneincreased，thestre