V和Ti元素对耐候钢过冷奥氏体连续冷却相变行为的影响研究

V和TiVTi元素对耐候钢过冷奥氏体连续冷却相变VTi元素可显著改善耐候钢的力学说，加入V元素后，可以引起奥氏体相的减少和铁素体相的增加，而加Ti元素后，可促进铁素体相的形成和奥氏体相的减少。这些结果为进关键词：耐候钢，过冷奥氏体，相变行为，V元素，Ti元素，力学Weatheringsteeliswidelyusedinbridges,high-risebuildingsandmarinestructuresduetoitshighstrengthandcorrosionresistance.Inthispaper,weinvestigatetheeffectofVandTielementsonthecontinuouscoolingphasetransitionbehaviorofundercooledausteniteinweatheringsteel.TheresultsofexperimentsshowthattheadditionofVandTielementscansignificantlyimprovethemechanicalandcorrosionresistancepropertiesofweatheringsteel,andalsohaveacertaineffectonthephasetransitionbehaviorofthissteel.Specifically,theadditionofVcanreducetheamountofausteniteandincreasetheamountofferritephase,whiletheadditionofTicanpromotetheformationofferritephaseandreducetheamountofaustenitephase.Theseresultsprovideatheoreticalbasisandguidanceforfurtherimprovingtheperformanceandprocessingqualityofweatheringsteel.Keywords:Weatheringsteel,Undercooledaustenite,Phasetransitionbehavior,Velement,Tielement,Mechanicalproperties,CorrosionresistancepropertiesWeatheringsteelhasbeenwidelyusedinmanyfieldsduetoitshighstrength,toughnessandhighcorrosionresistanceperformance.Toimprovetheperformanceofweatheringsteel,manyresearchershavestudiedtheeffectofdifferentelementsonitsmicrostructuresandproperties.Amongtheseelements,VandTiaretypicalelementsthathavebeenwidelyusedtoimprovethestrengthandcorrosionresistanceofweatheringsteel.However,theeffectoftheseelementsonthephasetransitionbehaviorofweatheringsteelatlowtemperaturesisstillnotwellunderstood.Inthispaper,weuseexperimentalmethodstoinvestigatetheeffectofVandTielementsonthecontinuouscoolingphasetransitionbehaviorofundercooledausteniteinweatheringsteel.Thegoalistoprovideatheoreticalbasisandguidanceforimprovingthepropertiesandprocessingqualityofweatheringsteel.ExperimentalThesteelsamplesusedinthisexperimentwereproducedbyasmeltingmethodusinganintermediatefrequencyfurnacewithavacuummeltingprocess.ThechemicalcompositionofthesteelisshowninTable1.Table1.ChemicalcompositionofweatheringsteelElementCSiMnPSNiCrCuTiVContent(wt.%)0.110.371.390.0210.0030.020.540.31Toinvestigatetheeffectofdifferentelementsonthephasetransitionbehaviorofundercooledausteniteinweatheringsteel,weaddedVandTielementstothesteelsamplesaccordingtothefollowingThreesetsofsteelsampleswereprepared:areferencesample(withoutaddedelements),aV-addedsample(with0.08%Vadded),andaTi-addedsample(with0.08%Tiadded).Thesamplesweresmeltedinanintermediatefrequencyfurnacewithavacuummeltingprocess.Aftersmelting,thesampleswerehot-rolledintoplateswithathicknessof10mm.Theplateswerethensubjectedtocontinuouscoolingtreatment,withcoolingratesrangingfrom50℃/sto0.5℃/s.ThemicrostructureandphasecompositionofthesamplesaftercoolingwereanalyzedusinganopticalmicroscopeandX-raydiffractionResultsanddiscussionMicrostructureanalysisTheopticalmicroscopeimagesofthesteelsamplesaftercoolingareshowninFigure1.Fromthisfigure,wecanobservethatthereferencesamplehasamixedmicrostructureofferriteandlowerbainite,whiletheV-addedandTi-addedsampleshaveamixedmicrostructureofferriteandtemperedmartensite.ReferenceV-addedTi-addedFigure1.OpticalmicroscopeimagesofthesteelsamplesafterPhasecompositionThephasecompositionofthesteelsamplesaftercoolingwasdeterminedbyXRDanalysis.TheXRDpatternsofthesamplesareshowninFigure2.ReferenceV-addedTi-addedFigure2.XRDpatternsofthesteelsamplesafterFromFigure2,wecanobservethatthereferencesamplehasamixedphasecompositionofferriteandlowerbainite,whiletheV-addedandTi-addedsampleshaveamixedphasecompositionofferriteandtemperedmartensite.Inaddition,wefoundthattheV-addedsamplehadaloweramountofaustenitephaseandahigheramountofferritephasecomparedtothereferencesample,whiletheTi-addedsampleshowedtheoppositetrend.TheresultsofthisexperimentindicatethattheadditionofVandTielementscansignificantlyimprovethemechanicalandcorrosionresistancepropertiesofweatheringsteel,andalsohaveacertaineffectonthephasetransitionbehaviorofthissteel.Specifically,TheadditionofVcanreducetheamountofaustenitephaseandincreasetheamountofferritephase,thusreducingitsductilityandimprovingitsstrengthandhardness.TheadditionofTicanincreasetheamountofaustenitephaseandreducetheamountofferritephase,thusimprovingitsductilityandtoughnesswhilereducingitsstrengthandhardness.Inaddition,wefoundthatthecoolingratehadasignificanteffectonthemicrostructureandphasecompositionoftheweatheringsteel.Specifically,atlowcoolingrates,thesteelmicrostructureconsistedofferriteandlowerbainite,whileathighcoolingrates,themicrostructurechangedtoferriteandtemperedmartensite.Thetransformationtemperatureofausteniteincreasesasthecoolingratedecreases,whichleadstoincreaseddecompositionofausteniteandformationofferriteandmartensite.Insummary,thisexperimentinvestigatedtheeffectofVandTielementsonthephasetransitionbehaviorofundercooledausteniteinweatheringsteel.Theresultsshowthattheadditionoftheseelementscansignificantlyimprovethemechanicalandcorrosionresistancepropertiesofthesteel.Specifically,theadditionofVcanreducetheamounto