简介:Anewtypeofnon-preheatedhardfacingelectrodewasdevelopedusingH08Aasthecoreandthecoatcontentsincludingferrotitanium,ferrovanadium,graphite,rutileetc.Themicrostructuresandpropertiesofhardfacingmetalweresystematicallyresearched.Theresultsshowthehardnessofhardfacingmetalincreaseswithincreasingofferrotitanium,ferrovanadium,graphiteinthecoat,butthecrackresistanceandprocessingweldabilitybecomeworse.Thecarbidesformedbyarcmetallurgicreactionareuniformlydispersedinthematrixstructure.Thephasesofhardfacingmetalconsistofα-Fe,γ-Fe,VC,TiCandFe3C.ThecarbidesarecompressionaggregationofTiCandVC,andtheirappearancespresentirregularblock.Thematrixmicrostructureofhardfacingmetalislathmartensite.Thehardfacinglayerswithbettercrackresistanceandwearabilityareachievedandnovisiblecracksoccurwhenusingnon-preheatedelectrodeincontinuousweldingprocess.Hardnessofhardfacingmetalismorethan60HRC,anditsrelativewearabilityisfivetimesofwearabilityofD667electrodeinabrasiveweartest.
简介:Vanadiumnitridewassynthesizedbyone-stepmethodusingV2O5andcarbonblackasrawmaterialsinnitrogenatmosphere.ThephasesofdifferentreactionproductspreparedindifferentreactiontemperatureswereanalyzedbyX-raydiffraction(XRD),andthedynamicbehavioroftheprocessofsynthesizingvanadiumnitride(VN)byone-stepmethodwasstudiedwithnon-isothermalthermogravimetry.Themechanismfunctionandkineticparametersofreactionprocesswerecalculatedbythermalgravimetricanalyses(TGA),andthereactionrateequationwasestablished.TheXRDresultsshowthatforthesamplestestedwithminimalVNafterholdingfor4hat1273K,themainphaseofproductsisVNat1476K,whilesomevanadiumnitridestransformintovanadiumcarbidesagainover1573K.ItisfoundthatN2isbeneficialtostimulatereductionandproceedcarbonizationreaction,andthereductionandnitridationreactioncanoccursimultaneously.TheactivationenergyofpreparingVNbyone-stepmethodis104.005kJ·mol-1,andthefrequencyfactoris470.52at1280–1358K,and150.052kJ·mol-1and2.359104at1358–1426K,respectively.
简介:MagneticBarkhausennoise(MBN)isaphenomenonofelectromagneticenergyduetothemovementofmagneticdomainwallsinsideferromagneticmaterialswhentheyarelocallymagnetizedbyanalternatingmagneticfields.AccordingtoFaraday’slawofelectromagneticinduction,thenoisecanbereceivedbythecoilattachedtothesurfaceofthematerialbeingmagnetizedandthenoisecarriesthemessageofthecharacteristicsofthematerialsuchasstresses,hardness,phasecontent,etc.Basedonthecharacteristicofthenoise,researchingabouttherelationshipbetweentheresidualstressintheweldingassemblyandthenoisearecarriedout.Furthermore,dataprocessisperformedbyRMS(RootMeanSquare)equationandPowerSpectrumanalysis.
简介:Thenon-isothermalleachingkineticsofprimarytitanium-richmaterialbymicrowaveheatingwasinvestigated,andthetemperature-pressurecurvesofleachingsystemandmicrowaveabsorptioncharacteristicsofmixturesolutionsbeforeandafterleachingweremeasured.Theresearchofnon-isothermalkineticswasevaluatedbytheleachingrateofFeandthetotalapparentvelocityequationofthenon-isothermalkineticsofleachingforprimarytitanium-richmaterialbymicrowaveheatingwasobtained.Itisshownfromthetemperature-pressurecurvesthatthehightemperatureandhighpressureofclosedleachingsystemarefavorabletotheenhancementoftheleachingrateofFe.Microwaveabsorptioncharacteristicsofmixturesolutionsbeforeandafterleachingshowthatthereareabruptchangesofmicrowaveabsorptioncharacteristicsfor15%HClsolutionandthemixturesolutionafterleachingby20%HCl.
简介:Anaxisymmetricfiniteelementmodelisdevelopedtosimulatethetemperaturefieldofresistantspotweldingaccordingtotheprocesscharactersofnuggetformationofnon-equalstainlesssteelsheets.Asimulationmethodoftheinteractionofelectricalandthermalfactorsispresented.Thespotweldingprocessofnuggetformationissimulatedusinghardandsoftweldingtechniquenorms.Theheatingcharactersofsoftandhardnormsdeterminethedifferencesintheprocessofnuggetformationanddeterminethefinallyshapeandoffsetofnugget.Experimentalverificationshowsthatthemodelpredictionagreeswellwiththepractical.
简介:Metallurgicalmodelingofsynergisticmicrocrackself-repairmenduringweldingsinglecrystalandpolycrystallinesuperalloysofhigh-temperatureaerospacematerialshasbeenproperlyestablished.Theideaofimprovementofnickel-basedsuperalloysweldabilitythroughnon-equilibriumsolidificationbehaviorofbackfilltoself-repairarterialcracknetworkisusefullyproposed.Crystallographiccontrolstrategyofcrackself-repairmenoffusionzoneinterdendriticsolidificationcrackingandheat-affectedzone(HAZ)intergranularliquationcrackingistechnicallyachievable,indicatingthatoptimalniobiumalloyingbeneficiallyrefinesweldmicrostructure,stabilizestheprimarysolidificationpath,increasesthesolidificationtemperatureandconcomitantlydecreasestheweldpoolgeometry.High-carbongrainboundaryismorethermalstableandlesscontributestoincipientintergranularliquidfilmthanthatoflow-carbongrainboundary.Thetheoreticalpredictionsofcrackingsusceptibilityareindirectlyverifiedinarathersatisfactorymanner.Additionally,themetallurgicalmodelingenhancespredicativecapabilitiesandtherebyisreadilyapplicableforotheralloysystems.