简介:为了对高合金异种钢焊接工艺有更多的了解,本文通过对某火力电厂锅炉后屏过热器检修换管过程中涉及到的钢种(SA213-T91马氏体高合金耐热钢与Cr25Ni13奥氏体高合金耐热钢)的现场焊接工艺进行介绍,以给类似工程的施工提供一定的借鉴。
简介:Forthedevelopmentofalow-melting-pointfillermetalforbrazingaluminumalloys,aseriesofAl-Si-Cu-(Ni,Sn,Zn)fillermetalshavebeenstudied.Throughdifferentialthermalanalysis(DTA),themeltingtemperaturesofsuchAl-Si-Cu-(Ni,Sn,Zn)fillermetalsweredetermined.Theresultsshowthattheadditionof3wt.%-5wt.%SnintotheAl-6Si-15Cufillermetalcausesitssolidustemperaturetodecreasebyabout12℃.ThefillermetalwiththecompositionAl-6Si-l5Cu-2Niisproposed,whichpossessesameltingtemperaturerangeof512℃to520℃andamicrostructarethatincludesanAl-Cueutecticphases,Al-Si-Cueutecticphases,siliconparticlesandCu_2Al,AlNi_3,Al_7Cu_4NiandAl_3Ni_2intermetalliccompounds.Anadditionof5wt.%-7wt.%ZnintosuchAl-Si-Cufillermetalscausetheirsolidustemperaturestodropfurthertoavaluelowerthan498℃.MetallographicobservationsindicatethattheadditionofZnintotheAl-Si-CufillermetalinhibitstheformationoftheAl-Si,Al-CuandAl-Si-Cueutecticphases.TheremainingphasesareaAl_2Cuintermetalliecompound,anα-Alsolidsolutionandsiliconparticles.
简介:Dynamicsinpartialtransientliquidphasebonding(PTLPbonding)ofSi3N4ceramicwithTi/Cu/Timulti-interlayerwassystematicallystudiedthroughmicro-analysisofjointinterfaces.Theresultsshowthatgrowthofreactionlayerandisothermalsolidificationprocessiondoatthesametime.GrowthofreactionlayerandmovingofisothermalsolidificationinterfaceobeytheparaboliclawgovernedbythediffusionofparticipatingelementsduringthePTLPbonding.Coordinationoftheabovetwodynamicsprocessisdonethroughtimeandtemperature.Whenreactionlayerthicknessissuitableandisothermalsolidificationprocessisfinished,thehighbondingstrengthatroomtemperatureandhightemperatureareobtained.
简介:ThevacuuminductionbrazingofSiCparticulatereinforcedLY12alloymatrixcompositeusingAl-28Cu-5Si-2Mgfillermetalhasbeencarriedout.Themicrographofthejointinterfacewasobservedbyscanningelectronmicroscopy.Thejointstrengthwasdeterminedbysheartests.Theresultsshowthatbrazingtemperature,holdingtime,SiCparticlevolumepercentageandpostheattreatmentinfluencejointstrength.SiCparticleshappeninthebrazingseamandthedistributionofSiCparticlesinthejointisnotuniform.Particle-poorzonesinthejointexistnearthebasemetal,andparticleconcentratezonesexistinthecenterofthebrazingseam.Inaddition,thefailureofthecompositeispredominantlyinitiatedbytherootingofSiCparticleinthebrazingseamandthemicro-crackexpandedalongthebrazingseamwithlowenergy.