Atomsondenuntersuchungen zur Diffusion von Si, Mn und Cr in einem perlitischen Stahl

Translated title of the contribution: Atom Probe Tomography Investigation of the Diffusion of Si, Mn, and Cr in a Pearlitic Steel

Armin Proyer

    Research output: ThesisMaster's Thesis


    When a steel is cooled from the austenitic area, the eutectoid reaction occurs after reaching the Ar1 temperature. Thereby pearlite is formed by a diffusion-controlled rearrangement of the alloying elements. If there is not enough time for this transformation, the sluggish diffusion of the substitution atoms can lead to concentration gradients at the interfaces between ferrite and cementite. The aim of this work was to investigate the influence of the cooling conditions on the diffusivity and on the distribution of the alloying elements Si, Mn, and Cr at the ferrite-cementite interfaces. In addition, it was examined whether the concentration gradients had any effect on the hardness of the material. Atom probe tomography was used to investigate the distribution of the elements. It was found that out of the selected parameters, the cooling rate has the greatest influence on the concentration gradient. With increasing cooling speed, the thickness of the lamella, at which concentration gradients can be found, decreases. This can be explained by the fact that the eutectoid transformation starts at a lower temperature, which limits the diffusivity of the atoms. In addition, the duration of the cooling process is shortened, which means that less time is available for diffusion. Furthermore, it turned out that the influence of the cooling conditions on the element distribution in cementite cannot be explained by the diffusion coefficients from the MOBFE5 database. It is therefore necessary to increase the pre-exponential term by a factor of at least 150. The investigation of hardness and pearlite lamellar spacing according to the Hall-Petch relationship shows no deviation from the expected linear behaviour, which is why a significant influence of the concentration gradients on the hardness can be ruled out.
    Translated title of the contributionAtom Probe Tomography Investigation of the Diffusion of Si, Mn, and Cr in a Pearlitic Steel
    Original languageGerman
    Awarding Institution
    • Montanuniversität
    • Schnitzer, Ronald, Supervisor (internal)
    • Landefeld, Andreas, Co-Supervisor (internal)
    Award date22 Oct 2021
    Publication statusPublished - 2021

    Bibliographical note

    embargoed until 14-09-2026


    • atom probe tomography
    • APT
    • element distribution
    • cooling conditions
    • cooling rate
    • interface
    • ferrite
    • cementite
    • diffusion
    • Si
    • Mn
    • Cr
    • pearlite
    • hypereutectoid
    • Hall-Petch
    • hardness
    • interlamellar spacing

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