Endre søk
RefereraExporteraLink to record
Permanent link

Direct link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
An experimental and theoretical study of precipitation during tempering of martensite in Fe-C-Cr alloys
KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallografi.ORCID-id: 0000-0003-4825-7430
2018 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
sted, utgiver, år, opplag, sider
Stockholm: KTH Royal Institute of Technology, 2018. , s. 59
HSV kategori
Identifikatorer
URN: urn:nbn:se:kth:diva-233502ISBN: 978-91-7729-843-4 (tryckt)OAI: oai:DiVA.org:kth-233502DiVA, id: diva2:1240344
Disputas
2018-09-14, sal F3, Lindstedtsvägen 26, Stockholm, 10:00 (engelsk)
Opponent
Veileder
Merknad

QC 20180821

Tilgjengelig fra: 2018-08-21 Laget: 2018-08-21 Sist oppdatert: 2020-05-11bibliografisk kontrollert
Delarbeid
1. Microstructure of Martensite in Fe-C-Cr and its Implications for Modelling of Carbide Precipitation during Tempering
Åpne denne publikasjonen i ny fane eller vindu >>Microstructure of Martensite in Fe-C-Cr and its Implications for Modelling of Carbide Precipitation during Tempering
Vise andre…
2014 (engelsk)Inngår i: ISIJ International, ISSN 0915-1559, E-ISSN 1347-5460, Vol. 54, nr 11, s. 2649-2656Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

The microstructure of as-quenched martensite in four Fe-C-Cr alloys (0.15C-1Cr, 0.15C-4Cr, 1C-1Cr, 1C-4Cr, mass%) has been investigated. Moreover, the microstructures served as input for setting up modeling of carbide precipitation during tempering of martensite. The modelling was conducted using the Langer-Schwartz approach and the software TC-PRISMA, which retrieves thermodynamic data from the Thermo-Calc databank. It was found that the martensite in the low carbon steels is predominantly lath martensite with units arranged parallel to each other. On the other hand, the plate martensite dominates the microstructure in the high carbon steels. The ratio of high-angle to low-angle grain boundaries was found to increase with increasing Cr in the low carbon steels, which indicates that Cr has a similar effect as C on the lath martensite microstructure, however, the micro-hardness remained unaffected by the addition of Cr. Finally, the precipitation modeling clearly demonstrates the importance of proper definition of the initial microstructure for predictive modelling. Parameters such as dislocation density and frequency of high-angle grain boundaries have a drastic effect on e.g. the mean size of carbides.

Emneord
steels, martensite, microstructure, precipitation, electron microscopy, modeling
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-158349 (URN)10.2355/isijinternational.54.2649 (DOI)000345485100030 ()2-s2.0-84917739189 (Scopus ID)
Merknad

QC 20150121

Tilgjengelig fra: 2015-01-21 Laget: 2015-01-07 Sist oppdatert: 2018-08-21bibliografisk kontrollert
2. Quantitative modeling and experimental verification of carbide precipitation in a martensitic Fe-0.16 wt%C-4.0 wt%Cr alloy
Åpne denne publikasjonen i ny fane eller vindu >>Quantitative modeling and experimental verification of carbide precipitation in a martensitic Fe-0.16 wt%C-4.0 wt%Cr alloy
Vise andre…
2016 (engelsk)Inngår i: Calphad, ISSN 0364-5916, E-ISSN 1873-2984, Vol. 53, s. 39-48Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Precipitation of carbides during tempering of a martensitic Fe-0.16 wt% C-4.0 wt% Cr alloy has been investigated by experimental analysis and quantitative modeling. It is found that both M7C3 and M23C6 form, at low- and high-angle grain boundaries in the martensite, as well as, at dislocations inside individual laths of martensite, during tempering at 700 °C. The applied Kampmann-Wagner numerical (KWN) modeling, utilizing CALPHAD thermodynamic and kinetic databases together with an assumption of local equilibrium and a constant tie-line, captures the main features of the precipitation, with a transient formation of metastable M23C6, and with M7C3 as the stable carbide. The predicted volume fraction and size are in reasonable agreement with extraction experiments for M7C3. However, for the metastable minority carbide M23C6, the modeling underestimates the size and overestimates the volume fraction within the transient time. With sound thermodynamic databases and physical parameter input, the adopted simplified modeling scheme is a valuable tool for materials design and optimization. Furthermore, by treating conditions at the phase interface more rigorously it is possible to account for different mechanisms of precipitation, such as e.g., non-partitioning local equilibrium, which could be important in systems where interstitial elements diffuse much faster than the substitutional ones.

sted, utgiver, år, opplag, sider
Elsevier, 2016
Emneord
Electron microscopy, Microstructure, Modeling, Precipitation, Steels, Tempering, Carbides, Chromium alloys, Grain boundaries, Martensite, Models, Phase interfaces, Steel, Volume fraction, Carbide precipitation, Different mechanisms, Experimental analysis, Experimental verification, High angle grain boundaries, Interstitial elements, Quantitative modeling, Thermodynamic database, Precipitation (chemical)
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-186937 (URN)10.1016/j.calphad.2016.03.001 (DOI)000377315100005 ()2-s2.0-84960155147 (Scopus ID)
Merknad

Funding Details: U1260204, NSFC, National Natural Science Foundation of China

QC 20160518

Tilgjengelig fra: 2016-05-18 Laget: 2016-05-16 Sist oppdatert: 2018-08-21bibliografisk kontrollert
3. Microstructure evolution during tempering of martensitic Fe-C-Cr alloys at 700 A degrees C
Åpne denne publikasjonen i ny fane eller vindu >>Microstructure evolution during tempering of martensitic Fe-C-Cr alloys at 700 A degrees C
2018 (engelsk)Inngår i: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 53, nr 9, s. 6939-6950Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

The microstructure evolution of two martensitic alloys Fe-0.15C-(1.0 and 4.0) Cr (wt%) was investigated, using X-ray diffraction, electron backscatter diffraction, electron channeling contrast imaging and transmission electron microscopy, after interrupted tempering at 700 A degrees C. It was found that quenching of 1-mm-thick samples in brine was sufficient to keep most of the carbon in solid solution in the martensite constituent. The high dislocation density of the martensite decreased rapidly during the initial tempering but continued tempering beyond a few minutes did not further reduce the dislocation density significantly. The initial martensitic microstructure with both coarse and fine laths coarsened slowly during tempering for both alloys. However, a clear difference between the two alloys was distinguished by studying units separated by high-angle boundaries (HABs). In the low-Cr alloy, M3C precipitates formed and coarsened rapidly, thus they caused little hindrance for migration of HABs, i.e., coarsening of the HAB units. On the other hand, in the high-Cr alloy, M7C3 precipitates formed and coarsened slowly, thus they were more effective in pinning the HABs than M3C in the low-Cr alloy, i.e., coarsening of HAB units was minute in the high-Cr alloy.

sted, utgiver, år, opplag, sider
SPRINGER, 2018
HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-223769 (URN)10.1007/s10853-018-2036-7 (DOI)000424874900054 ()2-s2.0-85040953153 (Scopus ID)
Forskningsfinansiär
VINNOVA
Merknad

QC 20180307

Tilgjengelig fra: 2018-03-07 Laget: 2018-03-07 Sist oppdatert: 2018-08-21bibliografisk kontrollert
4. Early stages of cementite precipitation during tempering of 1C-1Cr martensitic steel
Åpne denne publikasjonen i ny fane eller vindu >>Early stages of cementite precipitation during tempering of 1C-1Cr martensitic steel
(engelsk)Manuskript (preprint) (Annet vitenskapelig)
Abstract [en]

The precipitation of cementite (M3C) from as-quenched martensite during tempering at 500 and 700 °C was investigated in a Fe–1C–1Cr (wt. %) alloy. Tempering for a short duration at 700 °C results in a Cr/Fe ratio in the core region of M3C precipitates which is equal to the bulk alloy composition, while a shell on the surface of the precipitates exhibit a higher Cr concentration. With a prolonged tempering up to 5 hours, the shell concentration gradually increases towards the equilibrium value but the core region has not yet reached the equilibrium value. After tempering for 5 seconds at 500 °C, there is no Cr enrichment found at the M3C/matrix interface, while a transition to partitioning of Cr is found during the first 5 minutes of tempering at 500 °C. These experimental results indicate that M3C grows without significant partitioning of substitutional elements at both temperatures initially, i.e. growth is carbon diffusion controlled. This stage is, however, very short, and soon after 5 seconds at 700 °C and 5 min at 500 °C, Cr diffusion becomes important. Calculations using the diffusion simulation software DICTRA and precipitation simulation software TC-PRISMA were performed. The diffusion simulations using the local equilibrium interface condition show excellent agreement with experiments concerning Cr enrichment of the particles, but the size evolution is overestimated. On the other hand, the precipitation simulations underestimate the size evolution. It is suggested that a major improvement in the precipitation model could be achieved by implementing a modified nucleation model that considers nucleation far from the equilibrium composition.

HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-233448 (URN)
Merknad

QC 20180821

Tilgjengelig fra: 2018-08-20 Laget: 2018-08-20 Sist oppdatert: 2019-08-21bibliografisk kontrollert
5. Coarsening of cementite during tempering of a martensitic steel
Åpne denne publikasjonen i ny fane eller vindu >>Coarsening of cementite during tempering of a martensitic steel
(engelsk)Manuskript (preprint) (Annet vitenskapelig)
Abstract [en]

Coarsening of cementite (M3C) in a martensitic steel alloy Fe–1C–1Cr (wt. %) during tempering at 700 °C was investigated by electron microscopy and kinetic modelling. It is shown that the large M3C carbides are mostly located at high-angle grain boundaries in the coarsening stage and simple kinetic simulations predict the experimentally observed mean size evolution well when grain boundary diffusion of Cr is taken into account. However, the particle size distribution of M3C maintain a log-normal distribution throughout the whole extended tempering process (5000 h at 700 °C), which indicates that a modified LSW distribution , as predicted by classical steady-state coarsening theory , is not fully adequate for practical purposes in tempering of martensitic steels.

HSV kategori
Identifikatorer
urn:nbn:se:kth:diva-233449 (URN)
Merknad

QC 20180821

Tilgjengelig fra: 2018-08-20 Laget: 2018-08-20 Sist oppdatert: 2018-08-21bibliografisk kontrollert

Open Access i DiVA

fulltext(3467 kB)325 nedlastinger
Filinformasjon
Fil FULLTEXT01.pdfFilstørrelse 3467 kBChecksum SHA-512
5a722ae9346e7dea0c4d04366a505023140713ee3d653691d788696224e983d16515be385d683be9cf648550b09034f90df7137c6e73ccd346d8ea4b8601471b
Type fulltextMimetype application/pdf

Personposter BETA

Hou, Ziyong

Søk i DiVA

Av forfatter/redaktør
Hou, Ziyong
Av organisasjonen

Søk utenfor DiVA

GoogleGoogle Scholar
Totalt: 325 nedlastinger
Antall nedlastinger er summen av alle nedlastinger av alle fulltekster. Det kan for eksempel være tidligere versjoner som er ikke lenger tilgjengelige

isbn
urn-nbn

Altmetric

isbn
urn-nbn
Totalt: 1663 treff
RefereraExporteraLink to record
Permanent link

Direct link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf