Effect of pitting corrosion on very high cycle fatigue behavior.pdf

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1、http://www.paper.edu.cnScriptaMaterialia49(2003)711–716www.actamat-journals.comEffectofpittingcorrosiononveryhighcyclefatiguebehaviora,*bbQ.Y.Wang,N.Kawagoishi,Q.ChenaDepartmentofCivilEngineeringandMechanics,SichuanUniversity,Chengdu610065,ChinabDepartmentofMechanicalEngine

2、ering,KagoshimaUniversity,Kagoshima890-0065,JapanReceived9December2002;receivedinrevisedform30May2003;accepted17June2003AbstractInthisstudy,theeffectofpre-existingcorrosionpitsonthefatiguebehaviorof7075/T6aluminiumalloyinverylongliferangeandinthenearthresholdregimewasinvest

3、igatedbyusingpiezoelectricacceleratedfatiguetest.Theresultsindicatethatthepresenceofpre-existingcorrosionpits,producedby1-day,4-day,and7-dayimmersioninsaltwatersignificantlyreducesthefatiguelifeofthealuminumalloybyafactorof10–100.Ó2003ActaMaterialiaInc.PublishedbyElsevierLt

4、d.Allrightsreserved.Keywords:Pittingcorrosion;Verylonglifefatigue;7075/T6aluminumalloy;Near-thresholdcrackgrowth1.Introductionsionpitformation[2].Itiswellknownthatcor-rosionpittinghasastrongeffectonfatiguelifeofPitting(localized)corrosionleadingtofatiguestructuralAlalloys[1

5、–5].Undertheinteractionofcrackinitiationandcrackgrowthisconsideredtocyclicloadandthecorrosiveenvironment,cyclicbeamongthemostsignificantdamagemecha-loadingfacilitatesthepittingprocess,andcorro-nismsinagingstructures[1–3].Prior-corrosionsionpits,actingasgeometricaldiscontinu

6、ities,relatedfatigueprocessconsistsmainlyofpittingleadtocrackinitiationandpropagationandthennucleation,pitgrowth,transitionfrompittingtofinalfailure.Thepresenceoflocalizedcorrosionfatiguecrackinitiation,shortcrackgrowthandpitsmodifiesthelocalstressandmayultimatelylongcrackgr

7、owth[3–5].Pitsalmostalwaysinitiateshortenfatiguelifeandlowerthethresholdstressatsomechemicalorphysicalheterogeneityattheforcrackinitiationandpropagation.surface,suchasinclusions,second-phaseparticles,Althoughmuchfatiguedataofaluminiumal-flaws,mechanicaldamage,ordislocations

8、.Theloyshavebeenpublished,themostexperimentalaluminumalloyscontainnumerousconstituentdata