V和Ti元素對耐候鋼過冷奧氏體連續(xù)冷卻相變行為的影響研究

V和TiVTi元素對耐候鋼過冷奧氏體連續(xù)冷卻相變VTi元素可顯著改善耐候鋼的力學(xué)說，加入V元素后，可以引起奧氏體相的減少和鐵素體相的增加，而加Ti元素后，可促進(jìn)鐵素體相的形成和奧氏體相的減少。這些結(jié)果為進(jìn)關(guān)鍵詞：耐候鋼，過冷奧氏體，相變行為，V元素，Ti元素，力學(xué)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