《controlledlasertransf省略elbypulsedndya》

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1、ControlledLaserTransformationHardeningofMartensiticStainlessSteelbyPulsedNd:YAGLaserB.Mahmoudi,A.R.SabourAghdam,andM.J.Torkamanyeffectiveprotectivelayerbecauseofbrittlenessandcracksensitivity.Therefore,anoptimalphaseisneededtohavemorehardnesscomparedwit

2、hinitialferriteandmoretoughnesscomparedwithfullymartensitephase.AISI420MSShasmediumchromiumcontent(13%)andrelativelylowcarboncontent(~0.2%).Thehardnessofthismetalisvaryingbetween205VHNto550VHN(dependingoncarboncontent)[4].Theaimsofthepresentstudyaretoem

3、ployapulsedNd:YAGlaserforLTHofAISI420tocontrolthecarbideparticlesolutionintothematrixandobtainatemperedmartensitephasewithoptimumhardnessandtoughnessandcomparetheresultswithannealedandconventionallyhardenedone.Theeffectoflaserprocessparametersonthehardn

4、essanddepthofhardenedareaswereinvestigatedtoo.Abstract⎯Lasertransformationhardening(LTH)wasappliedtothesurfaceoftheAISI420martensiticstainlesssteelbyapulsedNd:YAGlasertoobtainoptimumhardness.Theinfluencesofprocesspara-meters(laserpulseenergy,durationtim

5、e,andtravelspeed)onthedepthandhardnessoflasertreatedareawereinvestigated.ImageanalysisofSEMmicros-tructureofAISI420showedthatplate-likecarbidehavealmostfullyand(30~40)%ofglobularcarbideparticlesdissolvedintothematrixafterlasertransformationhardeningbypu

6、lsedlaserandthemicrostructurewasrefinedtoobtaincontrolledtemperedmicrostructurewith450VHNhardness.martensiteIndexTerms⎯Lasertransformationhardening,martensiticstainlesssteel,martensitemicrostructure,pulsedNd:YAGlaser.doi:10.3969/j.issn.1674-862X.2010.01

7、.0192.ExperimentalDetails2.1MaterialandLaserAsheetofAISI420MSSwith3mmthicknesswascutto2cm×2cmsamples.ThechemicalcompositionofsamplesisshowninTable1.Preparingforlasersurfacetreatment,onesideofthesampleswaspolishedwith400-gritSiC.Inthepresetstudy,threekin

8、dsofspecimensfromthesameabovementionedmaterialwereexamined:as-received(AR),conventionallyheattreated(CHT)andlaserheattreated(LHT)samples.ARsampleswerefullyannealedinthefurnacetohavetheferritewithchromiumcarbideparticles.Asacompar