Endre søk
Begrens søket
1 - 7 of 7
RefereraExporteraLink til resultatlisten
Permanent 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
Treff pr side
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
Merk
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 1.
    Borgenstam, Annika
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallografi.
    Hedström, Peter
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallografi.
    Hillert, Mats
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallografi.
    Kolmskog, Peter
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallografi.
    Stormvinter, Albin
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallografi.
    Ågren, John
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallografi.
    On the Symmetry Among the Diffusional Transformation Products of Austenite2011Inngår i: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 42A, nr 6, s. 1558-1574Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Information on the diffusional transformation products of austenite in high-carbon steels is reviewed and supplemented with new microscopic studies. A comparison with transformation products in low-carbon steels indicates that there is a symmetry with pearlite in the middle, where ferrite and cementite are equal partners, and with acicular ferrite or cementite on each side. They both form with a surface relief, and at lower temperatures, each one is the leading phase in a eutectoid microstructure, bainite and inverse bainite, respectively. However, there is an asymmetry because at low temperatures bainite appears in high-carbon steels but inverse bainite never appears in low-carbon steels. At a constant high carbon content, there is another kind of symmetry, which is related to temperature. At intermediate temperatures the eutectoid reaction results in spherical nodules in which the cementite constituent originates from Widmanstatten plates. It turns spiky at both higher and lower temperatures with the leading phase in the spikes being cementite at higher temperatures and ferrite at lower temperatures. In the first kind of symmetry, there is an abrupt change among the three reaction products; in the second kind of symmetry, there is a gradual change. Accepting that all the eutectoid microstructures form by diffusion of carbon, one may explain the existence of both symmetries by the variation of the ratio of the supersaturations of ferrite and cementite with carbon content and with temperature.

  • 2.
    Kolmskog, Peter
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallografi.
    Does Bainite form with or without diffusion?: The experimental and theoretical evidence2013Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    With the increased interest in bainitic steels, fundamental understanding of the bainite transformationis of major importance. Unfortunately, the research on bainite has been hampered by an oldcontroversy on its formation mechanism. Over the years two quite different theories have developedclaiming to describe the bainite transformation i.e. the diffusionless and the diffusion controlledtheory. In this thesis, attention is directed towards fundamental understanding of the bainitetransformation and both experimental and theoretical approaches are used in order to reveal its truenatureIn the first part of this thesis the symmetry in the Fe-C phase diagram is studied. It is based on ametallographic mapping of microstructures using light optical microscopy and scanning electronmicroscopy in a high carbon steel. The mapping revealed symmetries both with respect to temperatureand carbon content and an acicular eutectoid with cementite as the leading phase was found andidentified as inverse bainite. By accepting that all the eutectoid microstructures forms by diffusion ofcarbon, one may explain the existence of symmetries in the Fe-C phase diagram. Additional supportof its existence is obtained from an observation of symmetries in an alloyed steel. From the performedwork it was concluded that the existence of symmetries among the eutectoid microstructures fromaustenite supports the idea that bainite forms by a diffusion controlled transformation.In the second part the growth of bainite is considered. An experimental study using laser scanningconfocal microscopy was performed and growth rates of the transformation products from austenite ina high carbon, high chromium steel was analysed. The growth rate measurements reveals the kineticrelation between Widmanstätten cementite and the acicular eutectoid previously identified as inversebainite which confirms its existence and the conclusions drawn in the first part. In addition, in-situobservations of bainite formation below Ms provide additional support for the diffusion controlledtheory for bainite formation.The final part of the work is a study of the critical conditions for the formation of acicular ferrite.Based on experimental information found in the literature a thermodynamic analysis is performed inview of the two theories. The results demonstrate that the governing process for Fe-C alloys cannot bediffusionless but both kinds of processes can formally be used for predicting Bs temperatures for Fe-Calloys.

  • 3.
    Kolmskog, Peter
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallografi.
    Borgenstam, Annika
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallografi.
    Eutectoid Transformations in 4.12 Mass Pct Cr 0.88 Mass Pct C Steel2011Inngår i: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 42A, nr 13, s. 3941-3951Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The sequence of eutectoid microstructures, obtained by lowering the temperature of the isothermal transformation, was studied in synthetic steel with 4.12 mass pct Cr 0.88 mass pct C. The results were compared with observations on plain carbon steels with 1.65 and 1.67 mass pct C. In both cases, the main features can be explained as an effect of a lowered temperature on the increasing supersaturation of cementite in austenite and an even stronger effect on that of ferrite. One distinction was a continuous change in the pearlite structure toward a more acicular structure. This structure is named acicular pearlite.

  • 4.
    Kolmskog, Peter
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallografi.
    Borgenstam, Annika
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallografi.
    Hillert, Mats
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Hedström, Peter
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallografi.
    Babu, Sudarsanam Suresh
    Terasaki, Hidenori
    Komizo, Yu-Ichi
    Direct Observation that Bainite can Grow Below M-S2012Inngår i: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 43A, nr 13, s. 4984-4988Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In situ simultaneous synchrotron X-ray diffraction and laser scanning confocal microscopy have confirmed that bainite in steels can grow below the martensite start temperature. This observation suggests that the formation curves for bainite in time-temperature-transformation diagrams should be extended below the martensite start temperature. Furthermore, the implication of this observation on the growth mechanism of bainitic ferrite is discussed.

  • 5.
    Kolmskog, Peter
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallografi.
    Borgenstam, Annika
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallografi.
    Höglund, Lars
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallografi.
    Hillert, Mats
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallografi.
    Thermodynamic Analysis of the Critical Condition for Acicular FerriteArtikkel i tidsskrift (Annet vitenskapelig)
  • 6.
    Kolmskog, Peter
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallografi.
    Hedström, Peter
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallografi.
    Borgenstam, Annika
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap, Metallografi.
    Kinetic Study of Transformations ofAustenite in a 4.12 mass% Cr 0.88 mass% C SteelManuskript (preprint) (Annet vitenskapelig)
  • 7.
    Leach, Lindsay
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Kolmskog, Peter
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Höglund, Lars
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Hillert, Mats
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Borgenstam, Annika
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Use of Fe-C Information as Reference for Alloying Effects on B-S2019Inngår i: Metallurgical and Materials Transactions. A, ISSN 1073-5623, E-ISSN 1543-1940, Vol. 50A, nr 10, s. 4531-4540Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Many empirical equations of the variation of the critical temperature with alloy content of the start of bainite formation in steels are available. They are often obtained by regression analysis of measured values for a large number of alloyed steels, usually with several alloying elements. However, such equations differ considerably, especially when applied to pure Fe-C alloys, which results in large differences between reported effects of individual alloying elements since they have not been based on the Fe-C system as a reference. Apparently, for the first time, an empirical equation is now derived by starting with information from Fe-C alloys and low alloy steels and then adding the effect of each alloying element separately, using information from ternary Fe-C-M alloys. Sets of information from the same alloy content but different carbon contents proved particularly useful. Lines connecting such points are regarded as B-S lines for the respective alloy content and the effect of alloying elements was evaluated from their distance from the B-S line for Fe-C alloys. Only under this condition can coefficients for alloying elements be expected to represent the physical effect of the elements. The resulting equation was tested with about 600 experimental B-S temperatures.

1 - 7 of 7
RefereraExporteraLink til resultatlisten
Permanent 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