2021-EffectoftooldesignandprocessparametersonpropertfrictionstirweldingJournalofMaterialsProcessingTechnology211(2021)972–977ContentslistsavailableatScienceDirectJournalofMaterialsProcessingTechnologyjournalhomepage:/locate/jmatprotecEffectoftooldesignandprocessparametersonpropertiesofAlalloy6016frictionstirspotweldsW.Yuana,R.S.Mishraa,,S.Webba,Y.L.Chenb,B.Carlsonb,D.R.Herlingc,G.J.GrantcaCenterforFrictionStirProcessing,DepartmentofMaterialsScienceandEngineering,MissouriUniversityofScienceandTechnology,Rolla,MO65409,USAGeneralMotorRDCenter,Warren,MI48090,USAcPacicNorthwestNationalLaboratory,Richland,WA99356,USAbarticleinfoabstractFrictionstirspotwelding(FSSW)ofAlalloy6016-T4sheetwasevaluatedusingaconventionalpin(CP)toolandoff-centerfeature(OC)tool.Toolrotationspeedandplungedepthwerevariedtodeterminetheeffectofindividualprocessparameteronlap-shearseparationload.Maximumseparationloadofabout3.3kNwasobtainedbyusinga0.2mmshoulderpenetrationdepthwith1500rpmtoolrotationspeedfortheCPtooland2500rpmfortheOCtool.Threedifferentweldseparationmodesunderlap-shearloadingwereobserved:interfacialseparation,nuggetfractureseparationanduppersheetfractureseparation.Microhardnessproleforweldcrosssectionindicatednodirectrelationshipbetweenmicrohardnessdistributionandseparationlocations.2021ElsevierB.V.Allrightsreserved.Articlehistory:Received26July2021Receivedinrevisedform7December2021Accepted17December2021Availableonline24December2021Keywords:FrictionstirspotweldingTooldesignAlalloy6016ProcessparameterSeparationmode1.IntroductionWeightsavingintheautomotiveindustryisbecomingincreas-inglyimportantandcanbeenhancedbyusinglight-weightaluminumalloyforvehicles;particularlyclosurepanelssuchashoods,decklidsandlift-gates.Resistancespotwelding(RSW),currentlythemostcommonlyusedjoiningtechniqueinthevehi-cleindustry,hasapplicationsforlow-carbon,high-strengthandcoatedsteels.However,RSWofaluminumalloysheetsisfraughtwithmanydisadvantages,whichincludeporosityandcracks,asreportedbyThorntonetal.(1996)andGeanetal.(1999).AsevereelectrodetipwearproblemhasalsobeenencounteredduringRSW(Khanetal.,2021).Recently,FSSWforjoiningaluminumalloysheethasbeendevelopedbyMazdaMotorCorporation(Sakanoetal.,2021)andKawasakiHeavyIndustry(Iwashita,2021).Similartofrictionstirwelding,whichwasdevelopedbyTWI,UKin1991(Thomasetal.,1991),FSSWisasolid-stateweldingtechnique.DuringplungetypeFSSW,arotatingtoolwithaprotrud-ingpinisinsertedintotheoverlappingsheetstoapredetermineddepth.Afteracertaindwelltime,itisretractedandakeyholeisleft.Thefrictionalheatgeneratedatthetool-workpieceinterfacesoftensthesurroundingmaterial,andtherotatingandmovingpincausesthematerialowinboththecircumferentialandtheaxialCorrespondingauthor.Tel.:+15733416361;fax:+15733416934.E-mailaddress:rsmishra@mst.edu(R.S.Mishra).0924-0136/$–seefrontmatter2021ElsevierB.V.Allrightsreserved.doi:10.1016/j.jmatprotec.2021.12.014directions(Lathabaietal.,2021).Theinter-mixingoftheplasticizedmaterialandforgingpressureappliedbythetoolshoulderresultintheformationofasolidbondregion(Freeneyetal.,2021).ThestrengthofweldsiscriticalwhenapplyingFSSWtoload-bearingcomponents.Thisstrengthisaffectedmainlybytoolgeometryandprocessparameters.Toolgeometry,suchasshoul-derdiameterandshape,pinshape,length,diameterandfeatureisakeyparametertoaffectheatgenerationandmaterialow(MishraandMa,2021).Currently,aconc...