简介:ThispaperdealswithastudyonSnPbandlead-freesolderedjointreliabilityofPLCCdeviceswithdifferentleadcountsunderthreekindsoftemperaturecycleprofiles,whichisbasedonnon-linearfiniteelementmethod.Byanalyzingthestressofsolderedjoints,itisfoundthatthelargeststressisattheareabetweenthesolderedjointsandtheleads,andanalysisresultsindicatethatthevonMisesstressatthelocationslightlyincreaseswiththeincreaseofleadcounts.ForPLCCwith84leadsthesolderedjointswasmodeledforthreetypicalloading(273-398K,218-398Kand198-398K)inordertostudytheinfluenceofaccelerationfactorsonthereliabilityofsolderedjoints.Andtheestimationofequivalentplasticstrainofthreedifferentlead-freesolderalloys(Sn3.8Ag0.7Cu,Sn3.5AgandSn37Pb)wasalsocarriedout.
简介:Thedigitalizationofarcweldingpowersourcemainlydependsonthedigitalizationofarcweldinginverter,sothatmaincircuitandcontrollingsystemcangivefullplaytoadvantages.DigitalswitchingcontrolmakesmaincircuitdigitalandDSPand/orMCUmakescontrollingsystem,digital.SoIGBTdrivingcircuit,asatieofmaincircuitandcontrollingsystem,shouldalsobegotdigitalized.Thus,adigitaldrivingcircuitbasedonoptocouplerdeviceHCPL-316Jisprovided.Sometestingexperimentsweredone.Afterdrivingtesting,thedrivingcircuitcertificatesthatdrivingwaveformssatisfytherequirementsofarcweldingpowersourceandthedrivingcircuitisreasonablyandsimplydesigned.Andthedrivingcircuithashighcontrollingprecisionandreliability.No-load-voltagetestingandweldingexternalcharacteristictestingprovethatthedrivingcircuitcanbeappliedinarcweldingpowersource.
简介:Inthispaper,themicrostructureandhardnessofHG980Dheat-affectedzone(HAZ)atdifferentcoolingratet8/3werestudied,theimplantcriticalfracturestressunderthreediffusiblehydrogenconditionsweremeasured,andthehydrogen-inducedcracking(HIC)fractographofsteelHG980Dwereanalyzed.TheexperimentalresultsshowthatmartensiteexistsinHAZofHG980Dtillt8/3≥150s,thehardenquenchingtendencyofHG980Disgreater;Theimplantcriticalfracturestressisrelatedtodiffusiblehydrogencontentsignificantly,atlowhydrogenlevel,highrestraintstressisneededtonucleateHIC,thefractographismainlymicrovoidcoalescence,butathighhydrogenlevel,onlysmallrestraintstresscancauseHICoccurrence,thefractographismainlyquasicleavage.Itisveryimportanttochooseultra-lowhydrogenweldingconsumabletoweldsteelHG980Dtopreventhydrogen-inducedcracking.
简介:Microstructuresandmechanicalpropertiesoftransientliquidphase(TLP)bondedmagnesiummetalmatrixcomposite(MMC)jointsusingcopperinterlayerhavebeeninvestigated.Withanincreaseofbondingtimesfrom5minto50minatbondingtemperatureof510℃,theaverageconcentrationofcopperinthebondedzonedecreased,themicrostructureinthezonechangedfromCu,α-MgandCuMg2toα-Mg,CuMg2andTiC,andmechanicalpropertiesofthejointincreased.Theshearstrengthofthejointbondedat510℃for50minreached64MPaduetothemetallurgicalbondingofthejointandimprovingitshomogeneityofcompositionandmicrostructure.ItisfavorabletoincreasethebondingtimeforimprovingmechanicalpropertiesofTLPbondedmagnesiumMMCjoint.