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Lecture

On phase transformations of high-alloy CrMnNi steels at high pressures up to 20 GPa

Thursday (27.09.2018)
18:15 - 18:30 S1/01 - A4
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Austenitic CrMnNi steels exhibit depending on the austenite stability and the stacking fault energy either deformation-induced martensitic phase transformation or mechanical twinning during static and cyclic loading both under uniaxial as well as multiaxial stress conditions. However, these steels undergo also a phase transformation under hydrostatic stress conditions at high hydrostatic pressures. For a metastable CrMnNi TRIP steel it was found by in situ synchrotron measurements that a transition of the deformation-induced martensitic phase transformation to the pressure-induced phase transformation was found to occur at a pressure range between 6 and 8 GPa [1]. Furthermore, clear differences regarding the microstructure and the morphology of the deformation-induced phases and the pressure-induced phases became evident [1]. In the present paper, high-pressure experiments were performed on two steels with different austenite stabilities up to different levels of hydrostatic pressure. Post-mortem EBSD measurements as well as ECCI investigations were performed in order to clarify the ongoing phase transformations at different pressures. The hydrostaticity of the high-pressure experiments, the influence of shear deformation and the influence of the austenite stability on the ongoing phase transformations and the range of pressure for transition from deformation-induced to pressure-induced transformation are discussed.

[1] S. Ackermann, S. Martin, M.R. Schwarz, C. Schimpf, D. Kulawinski, C. Lathe, S. Henkel, D. Rafaja, H. Biermann, A. Weidner: Investigation of phase transformations in high-alloy austenitic TRIP steel under high pressure (up to 18 GPa) by in situ synchrotron X-ray diffraction and scanning electron microscopy. Metall. Mater. Trans. 47A (2016) 95-111.

Speaker:
Dr.-Ing. Anja Weidner
TU Bergakademie Freiberg
Additional Authors:
  • Prof. Horst Biermann
    TU Bergakademie Freiberg
  • Carl Wolf
    TU Bergakademie Freiberg
  • Robert Lehnert
    TU Bergakademie Freiberg
  • Dr. Sebastian Henkel
    TU Bergakademie Freiberg
  • Dr. Stefan Martin
    TU Bergakademie Freiberg
  • Dr. Christian Schimpf
    TU Bergakademie Freiberg
  • Prof. David Rafaja
    TU Bergakademie Freiberg
  • Dr. Marcus R. Schwarz
    TU Bergakademie Freiberg
  • Dr. Christian Lathe
    Helmholtz Centre Potsdam
  • Dr. Robert Farla
    Deutsches Elektronen-Synchrotron DESY