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Title: Load partitioning between ferrite/martensite and dispersed nanoparticles of a 9Cr ferritic/martensitic (F/M) ODS steel at high temperatures

In thisstudy,ahigh-energysynchrotronradiationX-raytechniquewasusedtoinvestigatethetensile deformation processesofa9Cr-ODSferritic/martensitic(F/M)steelatdifferenttemperatures.Twominor phases withinthe9Cr-ODSF/Msteelmatrixwereidentified asY2Ti2O7 and TiNbythehigh-energyX-ray diffraction, andconfirmed bytheanalysisusingenergydispersiveX-rayspectroscopy(EDS)ofscanning transmission electronmicroscope(STEM).Thelatticestrainsofthematrixandparticlesweremeasured through theentiretensiledeformationprocess.Duringthetensiletests,thelatticestrainsoftheferrite/ martensiteandtheparticles(TiNandY2Ti2O7) showedastrongtemperaturedependence,decreasing with increasingtemperature.Analysisoftheinternalstressatthreetemperaturesshowedthattheload partitioning betweentheferrite/martensiteandtheparticles(TiNandY2Ti2O7) wasinitiatedduring sample yieldingandreachedtoapeakduringsamplenecking.Atthreestudiedtemperatures,the internal stressofminorphases(Y2Ti2O7 and TiN)wasabout2timesthatofF/Mmatrixatyielding position, whiletheinternalstressofY2Ti2O7 and TiNreachedabout4.5–6 timesand3–3.5 timesthatof the F/Mmatrixatneckingposition,respectively.Itindicatesthatthestrengtheningofthematrixisdueto minor phases(Y2Ti2O7 and TiN),especiallyY2Ti2O7 particles. Althoughtheinternalstressesofallphases decreased withincreasingtemperaturefromRTto600 °C, theratioofinternalstressesofeachphaseat necking positionstayedinastablerange(internalstressesofY2Ti2O7 and TiNwereabout4.5–6 times and 3–3.5 timesofthatofF/Mmatrix,respectively).ThedifferencebetweeninternalstressoftheF/M matrix andtheappliedstressat600 °C isslightlylowerthanthoseatRTand300 °C, indicatingthatthe nanoparticles stillhavegoodstrengtheningeffectat600 °C.
Authors:
; ; ; ; ; ;
Publication Date:
OSTI Identifier:
1227946
DOE Contract Number:
AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Science and Engineering. A, Structural Materials: Properties, Microstructure and Processing; Journal Volume: 637
Publisher:
Elsevier
Research Org:
Argonne National Laboratory (ANL)
Sponsoring Org:
USDOE Office of Science - Office of Basic Energy Sciences
Country of Publication:
United States
Language:
English
Subject:
Microstructure; Nanoscale particles; Synchrotron; Tensile deformation