钒对马氏体钢的PAG和力学性能的影响.pptx

NationalInstituteofFoundryandForgeTechnology,Ranchi DepartmentofMetallurgyandMaterials ReportSeminarPresentedby:-NITINKUMAR

Inrecentyears,UltraHighStrengthandexcellenttoughnesshasbeendemandedforthedevelopmentofhigh-performancemachinesLowalloymartensitesteelhaspotentialofachievinghighstrength.However,thetoughnessofmartensitesteelsisdecreasedasitsstrengthincreases.Whatisthemosteffectivewaytoacquireexcellentbalancebetweenstrengthandtoughness?Answeris,keepingLowcarbonanddoinggrainrefinement.Lathmartensitegenerallyappearinlowcarbon(0-.6wt.%c)lowalloysteelsandconsistofmulti-scalesubstructuressuchaspacket,blockandlath.Thepacketandblocksizesaretheimportantfactorswhichcanbeadjustedforachievingbothstrengthandtoughnessofmartensitesteels.Sincethesizesofpacketandblockinmartensitestronglydependontheprioraustenitegrainsize.Thepacketandblocksizesoflathmartensitewerebothrefinedastheaustenitegrainsizedecreased.

MethodofPrioraustenitegrainsizeRefinement.1controlledrolling. a.recrystallizationrolling(rollingabove950°cinausteniterecrystallizationregion) Averagegrainsizeofausteniteassmallas20μmwastherefinementlimitation. b.non-recrystallizationrolling(rollingbelow850°cinun-crystallizeregion) Averagegrainsizeofausteniteis5μm.2Heattreatment. Rapidcyclicheattreatmentcouldachieveultra-finegrainedaustenitewiththeaverage grainsizesmallerthan5μm.However,itwashardlyappliedinmassproductionforthe limitationsofcomplexprocessandspecimendimension.3CombiningcontrolledrollingandsimpleHeattreatment. thisistherecentmethodofachievingultrafinedgrainedaustenitesmallerthan5μm. HereVanadiuminsteadofniobiumischosenasthemicroalloyingelementtorestrain austeniterecrystallizationandgrowthincontrolledrollingandheattreatment.

1.EXPE