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简介：Theultra-finegrain(UFG)steelisweldedbyusingresistancespotweldingtechniquewithorwithoutrequirementofupsettingforce.Metallographicinspectionshowsthatthegrainsizeofweldnuggetislargerthanthatofthebasemetalandthemicrostructureisalteredsignificantly.Inaddition,contractingdefectssuchasairholescanbefoundinthenuggetcenter.Theexperimentsshowthatthedefectscanbeeffectivelyavoidedbythetechniqueofaddingupsettingforceduringthenuggetcoolingandcrystallizingprocesses.Intensilesheartests,theweldingjointstartstocrackfromtheinneredgeofthecoronabond.Theresultsofmicro-hardnesstestsshowthatthenewlybornmartensitestructuredramaticallyimprovesthehardnessofthejoint.Undertheinteractionsbetweenresidualstressesandregeneratedfinegrains,themicro-hardnessoftheheat-affectedzone(HAZ)islowerthanthatofthenugget,butevidentlyhigherthanthatofthebasemetal.

简介：精细化多功能智能焊接系统PMFWS-400是一种新型的采用全数字化的斩波式焊接装备，由直流电源供电，可实现手工焊、氩弧焊、脉冲氩弧焊、交直流氩弧焊、氩弧点焊、气保焊、单脉冲气保焊、双脉；中气保焊八种焊接方式，焊接性能达到了国际领先水平。可以实现焊接规范低于250A以下的碳钢薄板、不锈钢、铝及其合金薄板的精细化焊接，尤其适合不锈钢、

简介：Theeffectofnonmetallicinclusionsinthedropletofthestainlesssteelcoveredelectrodeontheporositywasresearched.Theresultshowsthatthenonmetallicinclusionsinthedropletarespherical,theircompositionisdifferentfromtheoneofslagandtheinclusionshavethecharacterof"innerformation".Whentheratioofrutiletoilmeniteinthecoatedmaterialisincreased,thedropletbecomescoarse,thecontentofnonmetallicinclusioninthedropletdecreases,andtheporositysensitivityintheweldmetalalsodecreases.Whentheratiooffledspartoilmeniteinthecoatedmaterialisincreased,thedropletbecomesfine,thecontentofnonmetallicinclusioninthedropletincreases,andtheporositysensitivityintheweldmetalincreases.WhentheratioofFe2O3toilmeniteinthecoatedmaterialisincreased,thedropletbecomesfine,thecontentofnonmetallicinclusiondecreases,whiletheporositysensitivitydoesnotreduce.

简介：WeldingresearchofA6N01S-T5aluminumalloyprofileforhigh-speedtrainwasdonebyusinglaser-MIGhybridweldingandMIGweldingindividually.Andtheweldappearance,weldingdistortion,mechanicalpropertiesofthejointsandmicrostructureswereanalyzed.Thetestresultsdemonstratedthathigh-efficientweldingfortheprofilecanbeachievedbyusinglaser-MIGhybridwelding,thespeedofwhichcanbeover3.0m/min.Theprocessinghadagoodgapbridgingability，evenifthegapofthebuttjointwasupto2.0mm,agoodweldappearancecanalsobegot.Whilethehybridweldingspeedwasgreaterthan2.5m/min,theweldingdistortionofthelaser-tandemMIGhybridjointswasjustabout33%ofthatoftheMIGjoints,buttheweldingefficiencywasover3timesofMIGwelding.Andtensilestrengthofthehybridjointswas85%ofthatofA6N01S-T5basemetal,9%higherthanthatoftheMIGjoints.Fatiguepropertieswastestedindividuallywithpulsedtensilefatiguemethodintheconditionof1×107lifetime.Thetestresultsdemonstratedthatthefatiguestrengthofthejointswasalittlelowerthanthatofbasematerial,whichcouldbeupto115MPa.Butthefatiguestrengthofhybridweldingjointswas107.5MPa,whichwas23%higherthan87MPaofMIGweldingjoints.

简介：ThesusceptibilityofweldedjointfortheX65pipelinesteeltoH2Sstresscorrosioncracking(SCC)isinvestigated.SCCtestsonthesteelarecarriedoutintheenvironmentbasedonNACETM-01-77solutionwithsaturatedgaseousH2S.Thethresholdstressintensityfactorandcrackpropagationvelocityarecalculatedaccordingtowedge-openingloading(WOL)specimens.Thethree-dimensionalelastic-plasticfiniteelementanalysisofWOLspecimensisperformedbyusingtheFEMprogrammingpackageANSYS.Stressfieldandconcentrationofhydrogendistributionpropertyaheadofthecracktipareobtained.ThispapersurveyedthemicrostructureofweldedjointandstudiedonthemechanicalpropertiesofX65pipelinesteel.Itprovidesexperimentalbasisforstudyingstresscorrosion.Theresultsofnumericalanalysisareconsistentwithconclusionsofstresscorrosiontest.

简介：北京市东升电焊机厂生产的ZX7-400ST手/氩两用焊机是具有国内先进水平、高效节能的焊接设备,具有直流手工电弧焊和直流氩弧焊两种工作方式。该焊机使用IGBT模块为开关元件,采用脉宽调制技术实现电流控制,具有良好的动特性和电网波动自动补偿功