40Cr钢超高周疲劳性能及疲劳断口分析

246Vol.24No.6200312CHINARAILWAYSCIENCEDecember═══════════════════════════════════════════════════════════════20031001-4632200306-0093-0640Cr61003140Cr105～101020kHz40CrS-N106107443MPa1010235MPa40CrTG142.15A2002-12-091960XJJQZ2002102GY029-02840Cr107109～10101071998EUROMECH382/FatigueintheGigacycleRegime2001FatigueintheVeryHighCycleRegimeS-N107S-N11071081072050215kHz～30kHz31071010640Cr105～1010S-N40Cr1!!11AB2Ux+pxU'x+K2Ux=01Uxxpx=S'xSxK=ωcc=Edﾍρω=2π}f2SxfρEd2yx=R1coshαx3α=1L1arccoshR2R()14L1R1R22Sx=πR22L1x≤LSx=πR21cosh2αxx≤L}15A0Ux=0=0Ux=L=A0U'x=L=061Ux=A0cosKL-xL1x≤LUx=A0φsinhβxcoshαxx≤L}17β=α2-Kﾍ28φ=cosKL2coshαL1sinhβL19L=L1+L2L1L2L2=1Karctan1KβtanhβL1-αtanhαL1[]{}101047εx=dUxdxσx=Edεx}11x=0σmax=A0Edβφ12σmaxA01µmx=0-M12M=Edβφ13!#40CrωC0.41%ωCr0.95%ωMn0.65%ωSi0.27%Fe∅1240Cr850℃560℃σb=915MPaσs=805MPa20kHz40CrEd=211GPaρ=7820kgm-34R1=1.5mmR2=5mmL1=14.1mmL2=16.4mm34924R0R0=L21+R2-R122R2-R114R0=30mm-M=27.32MPaum-1!#20kHzR=-1Ra=0.32µm～0.64µmphilip-XL302$!S-N40Crf=20kHzR=-1105～1010S-N340Crf=83.3HzR=-11074Basquin1.20kHzR=-12.83.3HzR=-1340CrS-Nσa=σ'f2Nfb12σ'fbBasquin40CrBasquin13Basquin106S-N105～101040CrS-Nσα10610940CrS-N105～107S-NS-N107420MPa443MPa101040Crσ-120kHz235MPa10101071S-NBasquinσˊfb2064-0.09130.95041914-0.10320.7479$$4σ=±500MPaN=9.92×1064SEM5a5b105～10940Cr59640Cr5a5b4+6a6aA6b7a7b450MPa3×107360MPa5.59×108+8N=9.92×105σ=±500MPa563!#40CrS-N105～1010S-N1010107Basquin1107107107N10769247SEMσ=±360MPaN=5.59×1088!#40Cr40Cr5TA6V417-4PHUdimet500S-N6σ'fσf2s-1～20s-110-3s-1～10-4s-1520Cr40Cr6Basquin!!40Cr7f=27Hz～100HzGr-Mo8OpticallyDarkAreaODA40Cr40Cr4140Cr105～1010S-NBasquin40Cr101010740Cr107107240Cr340Cr79640Cr41071BathiasC.ThereisnoInfiniteFatigueLifeinMetallicMaterialsJ.FatigueandFractureofEngineeringMaterialsandStruc-ture1999227559.2MansonWP.PiezoelectricCrystalsandtheirApplicationinUltrasonicsM.NewYorkUSAVanNostrand1950161.3RothLD.UltrasonicFatigueTestingM.MetalsHandbookVol.8.OhioUSAAmericanSocietyforMetals1995240258.4.M.1988265277.5ManjoineMJ.InfluenceofRateofStrainandTemperatureonYieldStressesofMildSteelJ.JApplMech.19442A-2116.20Cr40CrJ.1996438.7BathiasCJNi.AdvancesinFatigueLifetimePredictiveTechniquesM.ASTMPhiladelphia19932141.8MurakamiY.MechanismofFatigueFailureinUltralongLifeRegimeC.ProceedingsoftheInternationalConferenceonFatigueintheVeryHighCycleRegimeViennaAustria20011122.StudyontheGigacycleFatigueBehaviorsandFractureSurfaceof40CrSteelWANGHongGAOQingDepartmentofApplicationMechanicsandEngineeringSouthwestJiaotongUniversityChengduSichuan610031ChinaAbstractThefatiguebehaviorof40Crsteelbetween1051010cycleswasstudiedwiththeultrasonicfatiguetestingtechniquewithaloadingfrequencyofabout20kHz.ThefracturesurfacesofspecimenswereinvestigatedwithscanningelectronmicroscopySEM.TheexperimentalresultsshowthattheS-Ncurveof40Crsteelcontinuestodecreasewiththeincreaseofthenumberofcyclesbetween105and1010cyclesanddoesnotgenerallyexhibitaplateaubeyond106cy-cles.Thefatiguestrengthat107cyclesisfoundtobe443MPaandat1010cyclesis235MPa.Thedifferencebetweenthemisverylarge.Theobservationoffracturesurfaceshowsthatthemechanismoffatiguefailureissimilarinbothcasesofultrasonicfatigueandconventionalfatigueinlongliferegime.Cracksinitiatefromamassdefectofspecimensurfaceorbeneaththesurface.Thefatiguestriationareashavebeenfoundinthefracturesurfaceofspecimens.KeywordsSteelmaterialUltrasonicfatiguetestFatiguelifeFracturesurfaceTestanlaysis8924