简介:Anewapparatuswasdesignedtomeasuretheelectromagneticforceandacomputationalstudyofthetravelingmagneticfield(TMF)anditsapplicationtotheGa-In-Snmelt(withlowmeltingpoint),thentheforcesonAl,Mg,andLimelt,weresimulated.TheresultshowthattheelectromagneticforceonthemeltincreaseslinearlywiththeincreasinglengthofthemeltintheTMF.TheTMF-inducedLorentzforceincreaseswithincreasingfrequency,andthendecreases.Themaximumvalueisobtainedwhenthecurrentfrequencyis160Hz,overthatfrequencytheforcedecreasesrapidly.Whentheiron-coreisactivated,theforceincreaseswhenthemeltclosestotheiron-core.TheLorentzforceshaveinversely-proportionalrelationshipswiththeelectricalresistivity,thedfx/dρdecreasesandthedfy/dρincreaseswiththeincreasingelectricalresistivity(df/dρistheslopeoftheLorentzforceprofile).
简介:Theweldedjointofdissimilarheat-resistingsteels20Crl2MoV(F12)and12Cr2MoWVTiB(102)generallyworksaround600°C.Inthispaperthreekindsofferriticelectrodesareusedfortesting.TheyareR817high-strengthelectrode(CrllMoVNi),R347low-strengthelectrode(Cr2MoVWB)andnewly-developedR507MoNbmedium-strengthelectrode.Thestudyontheinfluenceofthosethreedifferentelectrodesoncarbonmigration,HICandhy-drogendiffusionshowsthatmedium-strengthelectrodescanwellcontrolthecarbonmigration,andthatthetendencytoHICinthejointformedbyR817issmallerthanthatbyR347instead.Consideringtheeffectofweldmetaltransfor-mationontherestraintstressandhydrogenconcentrationofajoint,thehydro-gendistributionintheheat-affectedzone(HAZ)iscalculatedbyusingfiniteele-mentmethod(FEM)withstressandstrainchanging,andsotheeffectofthetransformationbehaviouronHICisrevealed.Inaddition,newly-developedR507MoNbelectrodes,testedtheelevated-temperatureproperty,oxidationre-sistanceandcreeprupturestrength,havefulfilledthetechnicalstandardscon-cernedandpassedtheexaminationofon-the-spotoperation.
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简介:Themicrostructureofstress-inducedmartensite(SIM)inthenanocrystallineNiTialloywasinvestigatedbymeansoftransmissionelectronmicroscopy(TEM).Theresultshowsthatthemulti-variantstructureofthemartensiteissuppressedandonlysingle-variantmartensitictwinsformaftertensiledeformationwhenthegrainsizeissmallerthan80nm.Thenormaldirectionsofthe(001)B190twinplanesareallwithintherangeof45°fromtheaxialdirectionofthewire.Theanglebetweentwincrystals(1'11)Mand(111)ToftheSIMisalsofoundtobesmallerthanthatofthermallyinducedmartensiteinnanocrystallineNiTi.
简介:Theenergydepositionforlow-energyelectronbeamonSi-SiO2modelswascalculatedbyMonte-Carlomethod.Makinguseofelectronparamagneticresonance(EPR)technique,aninvestigationoftheeffectofdopanttypeandconcentrationonEPRsignalvariationswascarriedoutbyusingp-typeandn-typesilicon(111)waferswithconcentrationof1×1015cm3and1×1017cm3,andthechangesofintensityofdefectparamagneticcentersbeforeandafterirradiationofelectronswerecompared.Thechemicalstatesof...
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.