微量元素對18Ni系馬氏體時效鋼的力學性能和微觀組織的影響.pdf

1、江蘇科技大學碩士學位論文微量元素對18Ni系馬氏體時效鋼的力學性能和微觀組織的影響姓名：穆波申請學位級別：碩士專業(yè)：材料學指導(dǎo)教師：徐玉松20110614AbstractIIAbstractWiththedevelopmentoftechnologytherequirementtodevelopperfmancemachineryofequipmentgrowingquicklythehigherstrengthbettertoughn

2、essmaterialsappeared.Therefetheresearchoftheultrahighstrengthsteelisoneofthemajdevelopmentofmaterialsscience.Whenthemaragingsteelobtainahighintensityacertaintoughnesshasloosed.Indertoimprovethemechanicalpropertiesofmarag

3、ingsteeldevelophighstrengthtoughnessofmaragingsteelisparticularlyimptant.Inthisexperimentthecompositionsofmaragingsteelwasbasedon18Ni(250)steelNbelementwasaddedtoimprovethemicrostructureprosperities.VIMESRwasusedtoreduce

4、theimpurityelementsinthematerial.InvestigativetheeffectofNbonthemechanicalpropertiesmicrostructureofmaterial.ObservationofstrainrateonSCCbehavi.UsetheTEMtoanalysisthemicrostructureEDStodeterminetheprecipitate.Theresultss

5、howthat:traditionalmaragingsteelinthesuctioncastingprocesswillhavethecastdendritessegregationganization.ButthesegregationofmaterialsaddingNbisbetterthanthetraditionalmaterialsthecastcanbebasicallyeliminatedinhightemperat

6、urehomogenizationtreatment(1050℃2h).ThematerialscontainingNbaftersolutiontreatment(820℃1h)agingtreatment(480℃5h)reachedthemaximumhardness:HRC52.3.AddingNbmakesthematerialmicrostructurerefinementunifmimprovethemechanicalp

7、roperties.Whenthe18wt.%Nickelmaragingsteelinthestrainrateof0.6~3106s1Iδ35%showingacleartendencytostresscrosionhydrogenembittermentsensitiveareasasbutStrainrateof0.6~1105s1extensionoftheratesensitivityindexwas34.95%29.16%

8、asapotentialdangerzone.whilethespecimenstrainratehigherthan1105s1showedatendencytostresscrosionisnotobvious.TEMobservationshowedthat:themainprecipitatesof18wt.%Nickelmaragingsteelalongthe111directionofthematrixlyingonthe

9、（NiFeCo）3（TiMo）typeofrodlikeprecipitatesitshexagonalcrystalstructureNi3TiSystemNi3Mothethhombic.TherearefewFe2Mosphericalprecipitatesprecipitationtypeitsstructureishexagonal.18wt.%Nickelmaragingsteelahighdegreeofdislocat