Theformationofmartensiteduringthepropagationoffatiguecracksinpearliticrailsteel

Theformationofmartensiteduringthepropagationoffatiguecracksinpearliticrailsteel.pdf
Squatisakindofrailheaddefectsrelatedtorollingcontactfatigue(RCF),andregardedasapotentialsafetyhazardinrailwaynetworks.Themechanismsofsquatinitiationandpropagationremainunclearlyunderstood.Inthecurrentstudy,severalbranchesofsubsurfacecracksinsidesquatdefectshadbeenintensivelyinvestigatedforunderstandingthedevelopmentofRCFcracks.Frommetallographicobservations,afewwhiteetchingparticleswereclearlyfoundeitherlocatedwithincrackgapsorattachedwithcrackfaces.Basedonnanoindentationmeasurements,thehardnessofwhiteparticleswashigherthanthatinmatrix,presentingapossiblemechanicalpropertyofmartensite.Alargedensityofnano-twinsinthesubstructureofwhiteparticlescanbeidentifiedinthetransmissionelectronmicroscopybright-fieldimaging.TheircorrespondingselectedareaelectrondiffractionpatternsprovedwhiteparticlesasFe-Cmartensitewithbody-centeredtetragonalcrystallographicstructure.Besidesthemartensite,arandomdistributionofoxidizedsulphideinclusions(MnS)werefoundincludedinwhiteetchingparticlesaswellbytheenergy-dispersivex-rayspectroscopyanalyses.Thediscoveryofmartensitictransformationandsulphideinclusions(MnS)inthecrackofsquatdefectsrevealsanacceleratedfailuremechanismwhichwouldbedetrimentaltooperationsafety.Itisnecessarytopaymoreattentionssothattheriskoffatiguefailurescanbeminimized.
作者：J.P.Liu Q.Y.Zhou Y.H.Zhang F.S.Liu C.H.Tian X.Y.Zhi C.G.Li T.Shi
作者单位：MetalsandChemistryResearchInstitute,ChinaAcademyofRailwaySciences,Beijing100081,P.R.ChinaCARS(BEIJING)RailwayEquipmentTechnologyCo.,Ltd,Beijing102202,P.R.China
母体文献：中国铁道学会材料工艺委员会、工务委员会2018年钢轨使用技术学术交流会论文集
会议名称：中国铁道学会材料工艺委员会、工务委员会2018年钢轨使用技术学术交流会  
会议时间：2018年10月1日
会议地点：广州
主办单位：中国铁道学会
语种：chi
分类号：
关键词：Squats  Crackpropagation  Martensite  Rollingcontactfatigue  Railsteel
在线出版日期：2020年7月10日
基金项目：
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